Logo Search packages:      
Sourcecode: postgresql-8.4 version File versions

tablecmds.c

/*-------------------------------------------------------------------------
 *
 * tablecmds.c
 *      Commands for creating and altering table structures and settings
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.288 2009/06/18 01:27:02 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/reloptions.h"
#include "access/relscan.h"
#include "access/sysattr.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_depend.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_inherits_fn.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_tablespace.h"
#include "catalog/pg_trigger.h"
#include "catalog/pg_type.h"
#include "catalog/pg_type_fn.h"
#include "catalog/storage.h"
#include "catalog/toasting.h"
#include "commands/cluster.h"
#include "commands/defrem.h"
#include "commands/sequence.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "commands/trigger.h"
#include "commands/typecmds.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/parsenodes.h"
#include "optimizer/clauses.h"
#include "parser/gramparse.h"
#include "parser/parse_clause.h"
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "parser/parser.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteHandler.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/relcache.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/tqual.h"


/*
 * ON COMMIT action list
 */
typedef struct OnCommitItem
{
      Oid               relid;                  /* relid of relation */
      OnCommitAction oncommit;      /* what to do at end of xact */

      /*
       * If this entry was created during the current transaction,
       * creating_subid is the ID of the creating subxact; if created in a prior
       * transaction, creating_subid is zero.  If deleted during the current
       * transaction, deleting_subid is the ID of the deleting subxact; if no
       * deletion request is pending, deleting_subid is zero.
       */
      SubTransactionId creating_subid;
      SubTransactionId deleting_subid;
} OnCommitItem;

static List *on_commits = NIL;


/*
 * State information for ALTER TABLE
 *
 * The pending-work queue for an ALTER TABLE is a List of AlteredTableInfo
 * structs, one for each table modified by the operation (the named table
 * plus any child tables that are affected).  We save lists of subcommands
 * to apply to this table (possibly modified by parse transformation steps);
 * these lists will be executed in Phase 2.  If a Phase 3 step is needed,
 * necessary information is stored in the constraints and newvals lists.
 *
 * Phase 2 is divided into multiple passes; subcommands are executed in
 * a pass determined by subcommand type.
 */

#define AT_PASS_DROP                0           /* DROP (all flavors) */
#define AT_PASS_ALTER_TYPE          1           /* ALTER COLUMN TYPE */
#define AT_PASS_OLD_INDEX           2           /* re-add existing indexes */
#define AT_PASS_OLD_CONSTR          3           /* re-add existing constraints */
#define AT_PASS_COL_ATTRS           4           /* set other column attributes */
/* We could support a RENAME COLUMN pass here, but not currently used */
#define AT_PASS_ADD_COL             5           /* ADD COLUMN */
#define AT_PASS_ADD_INDEX           6           /* ADD indexes */
#define AT_PASS_ADD_CONSTR          7           /* ADD constraints, defaults */
#define AT_PASS_MISC                8           /* other stuff */
#define AT_NUM_PASSES               9

typedef struct AlteredTableInfo
{
      /* Information saved before any work commences: */
      Oid               relid;                  /* Relation to work on */
      char        relkind;          /* Its relkind */
      TupleDesc   oldDesc;          /* Pre-modification tuple descriptor */
      /* Information saved by Phase 1 for Phase 2: */
      List     *subcmds[AT_NUM_PASSES]; /* Lists of AlterTableCmd */
      /* Information saved by Phases 1/2 for Phase 3: */
      List     *constraints;  /* List of NewConstraint */
      List     *newvals;            /* List of NewColumnValue */
      bool        new_notnull;      /* T if we added new NOT NULL constraints */
      bool        new_changeoids; /* T if we added/dropped the OID column */
      Oid               newTableSpace;    /* new tablespace; 0 means no change */
      /* Objects to rebuild after completing ALTER TYPE operations */
      List     *changedConstraintOids;    /* OIDs of constraints to rebuild */
      List     *changedConstraintDefs;    /* string definitions of same */
      List     *changedIndexOids;         /* OIDs of indexes to rebuild */
      List     *changedIndexDefs;         /* string definitions of same */
} AlteredTableInfo;

/* Struct describing one new constraint to check in Phase 3 scan */
/* Note: new NOT NULL constraints are handled elsewhere */
typedef struct NewConstraint
{
      char     *name;               /* Constraint name, or NULL if none */
      ConstrType  contype;          /* CHECK or FOREIGN */
      Oid               refrelid;         /* PK rel, if FOREIGN */
      Oid               conid;                  /* OID of pg_constraint entry, if FOREIGN */
      Node     *qual;               /* Check expr or FkConstraint struct */
      List     *qualstate;          /* Execution state for CHECK */
} NewConstraint;

/*
 * Struct describing one new column value that needs to be computed during
 * Phase 3 copy (this could be either a new column with a non-null default, or
 * a column that we're changing the type of).  Columns without such an entry
 * are just copied from the old table during ATRewriteTable.  Note that the
 * expr is an expression over *old* table values.
 */
typedef struct NewColumnValue
{
      AttrNumber  attnum;                 /* which column */
      Expr     *expr;               /* expression to compute */
      ExprState  *exprstate;        /* execution state */
} NewColumnValue;

/*
 * Error-reporting support for RemoveRelations
 */
struct dropmsgstrings
{
      char        kind;
      int               nonexistent_code;
      const char *nonexistent_msg;
      const char *skipping_msg;
      const char *nota_msg;
      const char *drophint_msg;
};

static const struct dropmsgstrings dropmsgstringarray[] = {
      {RELKIND_RELATION,
            ERRCODE_UNDEFINED_TABLE,
            gettext_noop("table \"%s\" does not exist"),
            gettext_noop("table \"%s\" does not exist, skipping"),
            gettext_noop("\"%s\" is not a table"),
      gettext_noop("Use DROP TABLE to remove a table.")},
      {RELKIND_SEQUENCE,
            ERRCODE_UNDEFINED_TABLE,
            gettext_noop("sequence \"%s\" does not exist"),
            gettext_noop("sequence \"%s\" does not exist, skipping"),
            gettext_noop("\"%s\" is not a sequence"),
      gettext_noop("Use DROP SEQUENCE to remove a sequence.")},
      {RELKIND_VIEW,
            ERRCODE_UNDEFINED_TABLE,
            gettext_noop("view \"%s\" does not exist"),
            gettext_noop("view \"%s\" does not exist, skipping"),
            gettext_noop("\"%s\" is not a view"),
      gettext_noop("Use DROP VIEW to remove a view.")},
      {RELKIND_INDEX,
            ERRCODE_UNDEFINED_OBJECT,
            gettext_noop("index \"%s\" does not exist"),
            gettext_noop("index \"%s\" does not exist, skipping"),
            gettext_noop("\"%s\" is not an index"),
      gettext_noop("Use DROP INDEX to remove an index.")},
      {RELKIND_COMPOSITE_TYPE,
            ERRCODE_UNDEFINED_OBJECT,
            gettext_noop("type \"%s\" does not exist"),
            gettext_noop("type \"%s\" does not exist, skipping"),
            gettext_noop("\"%s\" is not a type"),
      gettext_noop("Use DROP TYPE to remove a type.")},
      {'\0', 0, NULL, NULL, NULL, NULL}
};


static void truncate_check_rel(Relation rel);
static List *MergeAttributes(List *schema, List *supers, bool istemp,
                        List **supOids, List **supconstr, int *supOidCount);
static bool MergeCheckConstraint(List *constraints, char *name, Node *expr);
static bool change_varattnos_walker(Node *node, const AttrNumber *newattno);
static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel);
static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
static void StoreCatalogInheritance(Oid relationId, List *supers);
static void StoreCatalogInheritance1(Oid relationId, Oid parentOid,
                                     int16 seqNumber, Relation inhRelation);
static int  findAttrByName(const char *attributeName, List *schema);
static void setRelhassubclassInRelation(Oid relationId, bool relhassubclass);
static void AlterIndexNamespaces(Relation classRel, Relation rel,
                               Oid oldNspOid, Oid newNspOid);
static void AlterSeqNamespaces(Relation classRel, Relation rel,
                           Oid oldNspOid, Oid newNspOid,
                           const char *newNspName);
static int transformColumnNameList(Oid relId, List *colList,
                                    int16 *attnums, Oid *atttypids);
static int transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
                                       List **attnamelist,
                                       int16 *attnums, Oid *atttypids,
                                       Oid *opclasses);
static Oid transformFkeyCheckAttrs(Relation pkrel,
                                    int numattrs, int16 *attnums,
                                    Oid *opclasses);
static void checkFkeyPermissions(Relation rel, int16 *attnums, int natts);
static void validateForeignKeyConstraint(FkConstraint *fkconstraint,
                                           Relation rel, Relation pkrel, Oid constraintOid);
static void createForeignKeyTriggers(Relation rel, FkConstraint *fkconstraint,
                                     Oid constraintOid);
static void ATController(Relation rel, List *cmds, bool recurse);
static void ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
              bool recurse, bool recursing);
static void ATRewriteCatalogs(List **wqueue);
static void ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
              AlterTableCmd *cmd);
static void ATRewriteTables(List **wqueue);
static void ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap);
static AlteredTableInfo *ATGetQueueEntry(List **wqueue, Relation rel);
static void ATSimplePermissions(Relation rel, bool allowView);
static void ATSimplePermissionsRelationOrIndex(Relation rel);
static void ATSimpleRecursion(List **wqueue, Relation rel,
                          AlterTableCmd *cmd, bool recurse);
static void ATOneLevelRecursion(List **wqueue, Relation rel,
                              AlterTableCmd *cmd);
static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse,
                        AlterTableCmd *cmd);
static void ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
                        ColumnDef *colDef, bool isOid);
static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid);
static void ATPrepAddOids(List **wqueue, Relation rel, bool recurse,
                    AlterTableCmd *cmd);
static void ATExecDropNotNull(Relation rel, const char *colName);
static void ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
                         const char *colName);
static void ATExecColumnDefault(Relation rel, const char *colName,
                              Node *newDefault);
static void ATPrepSetStatistics(Relation rel, const char *colName,
                              Node *flagValue);
static void ATExecSetStatistics(Relation rel, const char *colName,
                              Node *newValue);
static void ATExecSetStorage(Relation rel, const char *colName,
                         Node *newValue);
static void ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
                         DropBehavior behavior,
                         bool recurse, bool recursing);
static void ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
                     IndexStmt *stmt, bool is_rebuild);
static void ATExecAddConstraint(List **wqueue,
                              AlteredTableInfo *tab, Relation rel,
                              Node *newConstraint, bool recurse);
static void ATAddCheckConstraint(List **wqueue,
                               AlteredTableInfo *tab, Relation rel,
                               Constraint *constr,
                               bool recurse, bool recursing);
static void ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
                                      FkConstraint *fkconstraint);
static void ATExecDropConstraint(Relation rel, const char *constrName,
                               DropBehavior behavior,
                               bool recurse, bool recursing);
static void ATPrepAlterColumnType(List **wqueue,
                                AlteredTableInfo *tab, Relation rel,
                                bool recurse, bool recursing,
                                AlterTableCmd *cmd);
static void ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
                                const char *colName, TypeName *typename);
static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab);
static void ATPostAlterTypeParse(char *cmd, List **wqueue);
static void change_owner_recurse_to_sequences(Oid relationOid,
                                                  Oid newOwnerId);
static void ATExecClusterOn(Relation rel, const char *indexName);
static void ATExecDropCluster(Relation rel);
static void ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel,
                              char *tablespacename);
static void ATExecSetTableSpace(Oid tableOid, Oid newTableSpace);
static void ATExecSetRelOptions(Relation rel, List *defList, bool isReset);
static void ATExecEnableDisableTrigger(Relation rel, char *trigname,
                                       char fires_when, bool skip_system);
static void ATExecEnableDisableRule(Relation rel, char *rulename,
                                    char fires_when);
static void ATExecAddInherit(Relation rel, RangeVar *parent);
static void ATExecDropInherit(Relation rel, RangeVar *parent);
static void copy_relation_data(SMgrRelation rel, SMgrRelation dst,
                           ForkNumber forkNum, bool istemp);


/* ----------------------------------------------------------------
 *          DefineRelation
 *                      Creates a new relation.
 *
 * If successful, returns the OID of the new relation.
 * ----------------------------------------------------------------
 */
Oid
DefineRelation(CreateStmt *stmt, char relkind)
{
      char        relname[NAMEDATALEN];
      Oid               namespaceId;
      List     *schema = stmt->tableElts;
      Oid               relationId;
      Oid               tablespaceId;
      Relation    rel;
      TupleDesc   descriptor;
      List     *inheritOids;
      List     *old_constraints;
      bool        localHasOids;
      int               parentOidCount;
      List     *rawDefaults;
      List     *cookedDefaults;
      Datum       reloptions;
      ListCell   *listptr;
      AttrNumber  attnum;
      static char *validnsps[] = HEAP_RELOPT_NAMESPACES;

      /*
       * Truncate relname to appropriate length (probably a waste of time, as
       * parser should have done this already).
       */
      StrNCpy(relname, stmt->relation->relname, NAMEDATALEN);

      /*
       * Check consistency of arguments
       */
      if (stmt->oncommit != ONCOMMIT_NOOP && !stmt->relation->istemp)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("ON COMMIT can only be used on temporary tables")));

      /*
       * Look up the namespace in which we are supposed to create the relation.
       * Check we have permission to create there. Skip check if bootstrapping,
       * since permissions machinery may not be working yet.
       */
      namespaceId = RangeVarGetCreationNamespace(stmt->relation);

      if (!IsBootstrapProcessingMode())
      {
            AclResult   aclresult;

            aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(),
                                                              ACL_CREATE);
            if (aclresult != ACLCHECK_OK)
                  aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                                       get_namespace_name(namespaceId));
      }

      /*
       * Select tablespace to use.  If not specified, use default tablespace
       * (which may in turn default to database's default).
       */
      if (stmt->tablespacename)
      {
            tablespaceId = get_tablespace_oid(stmt->tablespacename);
            if (!OidIsValid(tablespaceId))
                  ereport(ERROR,
                              (errcode(ERRCODE_UNDEFINED_OBJECT),
                               errmsg("tablespace \"%s\" does not exist",
                                          stmt->tablespacename)));
      }
      else
      {
            tablespaceId = GetDefaultTablespace(stmt->relation->istemp);
            /* note InvalidOid is OK in this case */
      }

      /* Check permissions except when using database's default */
      if (OidIsValid(tablespaceId) && tablespaceId != MyDatabaseTableSpace)
      {
            AclResult   aclresult;

            aclresult = pg_tablespace_aclcheck(tablespaceId, GetUserId(),
                                                               ACL_CREATE);
            if (aclresult != ACLCHECK_OK)
                  aclcheck_error(aclresult, ACL_KIND_TABLESPACE,
                                       get_tablespace_name(tablespaceId));
      }

      /*
       * Parse and validate reloptions, if any.
       */
      reloptions = transformRelOptions((Datum) 0, stmt->options, NULL, validnsps,
                                                       true, false);

      (void) heap_reloptions(relkind, reloptions, true);

      /*
       * Look up inheritance ancestors and generate relation schema, including
       * inherited attributes.
       */
      schema = MergeAttributes(schema, stmt->inhRelations,
                                           stmt->relation->istemp,
                                           &inheritOids, &old_constraints, &parentOidCount);

      /*
       * Create a tuple descriptor from the relation schema.      Note that this
       * deals with column names, types, and NOT NULL constraints, but not
       * default values or CHECK constraints; we handle those below.
       */
      descriptor = BuildDescForRelation(schema);

      localHasOids = interpretOidsOption(stmt->options);
      descriptor->tdhasoid = (localHasOids || parentOidCount > 0);

      /*
       * Find columns with default values and prepare for insertion of the
       * defaults.  Pre-cooked (that is, inherited) defaults go into a list of
       * CookedConstraint structs that we'll pass to heap_create_with_catalog,
       * while raw defaults go into a list of RawColumnDefault structs that will
       * be processed by AddRelationNewConstraints.  (We can't deal with raw
       * expressions until we can do transformExpr.)
       *
       * We can set the atthasdef flags now in the tuple descriptor; this just
       * saves StoreAttrDefault from having to do an immediate update of the
       * pg_attribute rows.
       */
      rawDefaults = NIL;
      cookedDefaults = NIL;
      attnum = 0;

      foreach(listptr, schema)
      {
            ColumnDef  *colDef = lfirst(listptr);

            attnum++;

            if (colDef->raw_default != NULL)
            {
                  RawColumnDefault *rawEnt;

                  Assert(colDef->cooked_default == NULL);

                  rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
                  rawEnt->attnum = attnum;
                  rawEnt->raw_default = colDef->raw_default;
                  rawDefaults = lappend(rawDefaults, rawEnt);
                  descriptor->attrs[attnum - 1]->atthasdef = true;
            }
            else if (colDef->cooked_default != NULL)
            {
                  CookedConstraint *cooked;

                  cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
                  cooked->contype = CONSTR_DEFAULT;
                  cooked->name = NULL;
                  cooked->attnum = attnum;
                  cooked->expr = stringToNode(colDef->cooked_default);
                  cooked->is_local = true;      /* not used for defaults */
                  cooked->inhcount = 0;         /* ditto */
                  cookedDefaults = lappend(cookedDefaults, cooked);
                  descriptor->attrs[attnum - 1]->atthasdef = true;
            }
      }

      /*
       * Create the relation.  Inherited defaults and constraints are passed in
       * for immediate handling --- since they don't need parsing, they can be
       * stored immediately.
       */
      relationId = heap_create_with_catalog(relname,
                                                              namespaceId,
                                                              tablespaceId,
                                                              InvalidOid,
                                                              GetUserId(),
                                                              descriptor,
                                                              list_concat(cookedDefaults,
                                                                                old_constraints),
                                                              relkind,
                                                              false,
                                                              localHasOids,
                                                              parentOidCount,
                                                              stmt->oncommit,
                                                              reloptions,
                                                              allowSystemTableMods);

      StoreCatalogInheritance(relationId, inheritOids);

      /*
       * We must bump the command counter to make the newly-created relation
       * tuple visible for opening.
       */
      CommandCounterIncrement();

      /*
       * Open the new relation and acquire exclusive lock on it.  This isn't
       * really necessary for locking out other backends (since they can't see
       * the new rel anyway until we commit), but it keeps the lock manager from
       * complaining about deadlock risks.
       */
      rel = relation_open(relationId, AccessExclusiveLock);

      /*
       * Now add any newly specified column default values and CHECK constraints
       * to the new relation.  These are passed to us in the form of raw
       * parsetrees; we need to transform them to executable expression trees
       * before they can be added. The most convenient way to do that is to
       * apply the parser's transformExpr routine, but transformExpr doesn't
       * work unless we have a pre-existing relation. So, the transformation has
       * to be postponed to this final step of CREATE TABLE.
       */
      if (rawDefaults || stmt->constraints)
            AddRelationNewConstraints(rel, rawDefaults, stmt->constraints,
                                                  true, true);

      /*
       * Clean up.  We keep lock on new relation (although it shouldn't be
       * visible to anyone else anyway, until commit).
       */
      relation_close(rel, NoLock);

      return relationId;
}

/*
 * Emit the right error or warning message for a "DROP" command issued on a
 * non-existent relation
 */
static void
DropErrorMsgNonExistent(const char *relname, char rightkind, bool missing_ok)
{
      const struct dropmsgstrings *rentry;

      for (rentry = dropmsgstringarray; rentry->kind != '\0'; rentry++)
      {
            if (rentry->kind == rightkind)
            {
                  if (!missing_ok)
                  {
                        ereport(ERROR,
                                    (errcode(rentry->nonexistent_code),
                                     errmsg(rentry->nonexistent_msg, relname)));
                  }
                  else
                  {
                        ereport(NOTICE, (errmsg(rentry->skipping_msg, relname)));
                        break;
                  }
            }
      }

      Assert(rentry->kind != '\0');       /* Should be impossible */
}

/*
 * Emit the right error message for a "DROP" command issued on a
 * relation of the wrong type
 */
static void
DropErrorMsgWrongType(const char *relname, char wrongkind, char rightkind)
{
      const struct dropmsgstrings *rentry;
      const struct dropmsgstrings *wentry;

      for (rentry = dropmsgstringarray; rentry->kind != '\0'; rentry++)
            if (rentry->kind == rightkind)
                  break;
      Assert(rentry->kind != '\0');

      for (wentry = dropmsgstringarray; wentry->kind != '\0'; wentry++)
            if (wentry->kind == wrongkind)
                  break;
      /* wrongkind could be something we don't have in our table... */

      ereport(ERROR,
                  (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                   errmsg(rentry->nota_msg, relname),
         (wentry->kind != '\0') ? errhint("%s", _(wentry->drophint_msg)) : 0));
}

/*
 * RemoveRelations
 *          Implements DROP TABLE, DROP INDEX, DROP SEQUENCE, DROP VIEW
 */
void
RemoveRelations(DropStmt *drop)
{
      ObjectAddresses *objects;
      char        relkind;
      ListCell   *cell;

      /*
       * First we identify all the relations, then we delete them in a single
       * performMultipleDeletions() call.  This is to avoid unwanted DROP
       * RESTRICT errors if one of the relations depends on another.
       */

      /* Determine required relkind */
      switch (drop->removeType)
      {
            case OBJECT_TABLE:
                  relkind = RELKIND_RELATION;
                  break;

            case OBJECT_INDEX:
                  relkind = RELKIND_INDEX;
                  break;

            case OBJECT_SEQUENCE:
                  relkind = RELKIND_SEQUENCE;
                  break;

            case OBJECT_VIEW:
                  relkind = RELKIND_VIEW;
                  break;

            default:
                  elog(ERROR, "unrecognized drop object type: %d",
                         (int) drop->removeType);
                  relkind = 0;            /* keep compiler quiet */
                  break;
      }

      /* Lock and validate each relation; build a list of object addresses */
      objects = new_object_addresses();

      foreach(cell, drop->objects)
      {
            RangeVar   *rel = makeRangeVarFromNameList((List *) lfirst(cell));
            Oid               relOid;
            HeapTuple   tuple;
            Form_pg_class classform;
            ObjectAddress obj;

            /*
             * These next few steps are a great deal like relation_openrv, but we
             * don't bother building a relcache entry since we don't need it.
             *
             * Check for shared-cache-inval messages before trying to access the
             * relation.  This is needed to cover the case where the name
             * identifies a rel that has been dropped and recreated since the
             * start of our transaction: if we don't flush the old syscache entry,
             * then we'll latch onto that entry and suffer an error later.
             */
            AcceptInvalidationMessages();

            /* Look up the appropriate relation using namespace search */
            relOid = RangeVarGetRelid(rel, true);

            /* Not there? */
            if (!OidIsValid(relOid))
            {
                  DropErrorMsgNonExistent(rel->relname, relkind, drop->missing_ok);
                  continue;
            }

            /*
             * In DROP INDEX, attempt to acquire lock on the parent table before
             * locking the index.  index_drop() will need this anyway, and since
             * regular queries lock tables before their indexes, we risk deadlock
             * if we do it the other way around.  No error if we don't find a
             * pg_index entry, though --- that most likely means it isn't an
             * index, and we'll fail below.
             */
            if (relkind == RELKIND_INDEX)
            {
                  tuple = SearchSysCache(INDEXRELID,
                                                   ObjectIdGetDatum(relOid),
                                                   0, 0, 0);
                  if (HeapTupleIsValid(tuple))
                  {
                        Form_pg_index index = (Form_pg_index) GETSTRUCT(tuple);

                        LockRelationOid(index->indrelid, AccessExclusiveLock);
                        ReleaseSysCache(tuple);
                  }
            }

            /* Get the lock before trying to fetch the syscache entry */
            LockRelationOid(relOid, AccessExclusiveLock);

            tuple = SearchSysCache(RELOID,
                                             ObjectIdGetDatum(relOid),
                                             0, 0, 0);
            if (!HeapTupleIsValid(tuple))
                  elog(ERROR, "cache lookup failed for relation %u", relOid);
            classform = (Form_pg_class) GETSTRUCT(tuple);

            if (classform->relkind != relkind)
                  DropErrorMsgWrongType(rel->relname, classform->relkind, relkind);

            /* Allow DROP to either table owner or schema owner */
            if (!pg_class_ownercheck(relOid, GetUserId()) &&
                  !pg_namespace_ownercheck(classform->relnamespace, GetUserId()))
                  aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                       rel->relname);

            if (!allowSystemTableMods && IsSystemClass(classform))
                  ereport(ERROR,
                              (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                               errmsg("permission denied: \"%s\" is a system catalog",
                                          rel->relname)));

            /* OK, we're ready to delete this one */
            obj.classId = RelationRelationId;
            obj.objectId = relOid;
            obj.objectSubId = 0;

            add_exact_object_address(&obj, objects);

            ReleaseSysCache(tuple);
      }

      performMultipleDeletions(objects, drop->behavior);

      free_object_addresses(objects);
}

/*
 * ExecuteTruncate
 *          Executes a TRUNCATE command.
 *
 * This is a multi-relation truncate.  We first open and grab exclusive
 * lock on all relations involved, checking permissions and otherwise
 * verifying that the relation is OK for truncation.  In CASCADE mode,
 * relations having FK references to the targeted relations are automatically
 * added to the group; in RESTRICT mode, we check that all FK references are
 * internal to the group that's being truncated.  Finally all the relations
 * are truncated and reindexed.
 */
void
ExecuteTruncate(TruncateStmt *stmt)
{
      List     *rels = NIL;
      List     *relids = NIL;
      List     *seq_relids = NIL;
      EState         *estate;
      ResultRelInfo *resultRelInfos;
      ResultRelInfo *resultRelInfo;
      ListCell   *cell;

      /*
       * Open, exclusive-lock, and check all the explicitly-specified relations
       */
      foreach(cell, stmt->relations)
      {
            RangeVar   *rv = lfirst(cell);
            Relation    rel;
            bool        recurse = interpretInhOption(rv->inhOpt);
            Oid               myrelid;

            rel = heap_openrv(rv, AccessExclusiveLock);
            myrelid = RelationGetRelid(rel);
            /* don't throw error for "TRUNCATE foo, foo" */
            if (list_member_oid(relids, myrelid))
            {
                  heap_close(rel, AccessExclusiveLock);
                  continue;
            }
            truncate_check_rel(rel);
            rels = lappend(rels, rel);
            relids = lappend_oid(relids, myrelid);

            if (recurse)
            {
                  ListCell   *child;
                  List     *children;

                  children = find_all_inheritors(myrelid, AccessExclusiveLock);

                  foreach(child, children)
                  {
                        Oid               childrelid = lfirst_oid(child);

                        if (list_member_oid(relids, childrelid))
                              continue;

                        /* find_all_inheritors already got lock */
                        rel = heap_open(childrelid, NoLock);
                        truncate_check_rel(rel);
                        rels = lappend(rels, rel);
                        relids = lappend_oid(relids, childrelid);
                  }
            }
      }

      /*
       * In CASCADE mode, suck in all referencing relations as well.    This
       * requires multiple iterations to find indirectly-dependent relations. At
       * each phase, we need to exclusive-lock new rels before looking for their
       * dependencies, else we might miss something.  Also, we check each rel as
       * soon as we open it, to avoid a faux pas such as holding lock for a long
       * time on a rel we have no permissions for.
       */
      if (stmt->behavior == DROP_CASCADE)
      {
            for (;;)
            {
                  List     *newrelids;

                  newrelids = heap_truncate_find_FKs(relids);
                  if (newrelids == NIL)
                        break;                  /* nothing else to add */

                  foreach(cell, newrelids)
                  {
                        Oid               relid = lfirst_oid(cell);
                        Relation    rel;

                        rel = heap_open(relid, AccessExclusiveLock);
                        ereport(NOTICE,
                                    (errmsg("truncate cascades to table \"%s\"",
                                                RelationGetRelationName(rel))));
                        truncate_check_rel(rel);
                        rels = lappend(rels, rel);
                        relids = lappend_oid(relids, relid);
                  }
            }
      }

      /*
       * Check foreign key references.  In CASCADE mode, this should be
       * unnecessary since we just pulled in all the references; but as a
       * cross-check, do it anyway if in an Assert-enabled build.
       */
#ifdef USE_ASSERT_CHECKING
      heap_truncate_check_FKs(rels, false);
#else
      if (stmt->behavior == DROP_RESTRICT)
            heap_truncate_check_FKs(rels, false);
#endif

      /*
       * If we are asked to restart sequences, find all the sequences, lock them
       * (we only need AccessShareLock because that's all that ALTER SEQUENCE
       * takes), and check permissions.  We want to do this early since it's
       * pointless to do all the truncation work only to fail on sequence
       * permissions.
       */
      if (stmt->restart_seqs)
      {
            foreach(cell, rels)
            {
                  Relation    rel = (Relation) lfirst(cell);
                  List     *seqlist = getOwnedSequences(RelationGetRelid(rel));
                  ListCell   *seqcell;

                  foreach(seqcell, seqlist)
                  {
                        Oid               seq_relid = lfirst_oid(seqcell);
                        Relation    seq_rel;

                        seq_rel = relation_open(seq_relid, AccessShareLock);

                        /* This check must match AlterSequence! */
                        if (!pg_class_ownercheck(seq_relid, GetUserId()))
                              aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                                   RelationGetRelationName(seq_rel));

                        seq_relids = lappend_oid(seq_relids, seq_relid);

                        relation_close(seq_rel, NoLock);
                  }
            }
      }

      /* Prepare to catch AFTER triggers. */
      AfterTriggerBeginQuery();

      /*
       * To fire triggers, we'll need an EState as well as a ResultRelInfo for
       * each relation.
       */
      estate = CreateExecutorState();
      resultRelInfos = (ResultRelInfo *)
            palloc(list_length(rels) * sizeof(ResultRelInfo));
      resultRelInfo = resultRelInfos;
      foreach(cell, rels)
      {
            Relation    rel = (Relation) lfirst(cell);

            InitResultRelInfo(resultRelInfo,
                                      rel,
                                      0,  /* dummy rangetable index */
                                      CMD_DELETE,     /* don't need any index info */
                                      false);
            resultRelInfo++;
      }
      estate->es_result_relations = resultRelInfos;
      estate->es_num_result_relations = list_length(rels);

      /*
       * Process all BEFORE STATEMENT TRUNCATE triggers before we begin
       * truncating (this is because one of them might throw an error). Also, if
       * we were to allow them to prevent statement execution, that would need
       * to be handled here.
       */
      resultRelInfo = resultRelInfos;
      foreach(cell, rels)
      {
            estate->es_result_relation_info = resultRelInfo;
            ExecBSTruncateTriggers(estate, resultRelInfo);
            resultRelInfo++;
      }

      /*
       * OK, truncate each table.
       */
      foreach(cell, rels)
      {
            Relation    rel = (Relation) lfirst(cell);
            Oid               heap_relid;
            Oid               toast_relid;

            /*
             * Create a new empty storage file for the relation, and assign it as
             * the relfilenode value.     The old storage file is scheduled for
             * deletion at commit.
             */
            setNewRelfilenode(rel, RecentXmin);

            heap_relid = RelationGetRelid(rel);
            toast_relid = rel->rd_rel->reltoastrelid;

            /*
             * The same for the toast table, if any.
             */
            if (OidIsValid(toast_relid))
            {
                  rel = relation_open(toast_relid, AccessExclusiveLock);
                  setNewRelfilenode(rel, RecentXmin);
                  heap_close(rel, NoLock);
            }

            /*
             * Reconstruct the indexes to match, and we're done.
             */
            reindex_relation(heap_relid, true);
      }

      /*
       * Process all AFTER STATEMENT TRUNCATE triggers.
       */
      resultRelInfo = resultRelInfos;
      foreach(cell, rels)
      {
            estate->es_result_relation_info = resultRelInfo;
            ExecASTruncateTriggers(estate, resultRelInfo);
            resultRelInfo++;
      }

      /* Handle queued AFTER triggers */
      AfterTriggerEndQuery(estate);

      /* We can clean up the EState now */
      FreeExecutorState(estate);

      /* And close the rels (can't do this while EState still holds refs) */
      foreach(cell, rels)
      {
            Relation    rel = (Relation) lfirst(cell);

            heap_close(rel, NoLock);
      }

      /*
       * Lastly, restart any owned sequences if we were asked to.  This is done
       * last because it's nontransactional: restarts will not roll back if we
       * abort later.  Hence it's important to postpone them as long as
       * possible.  (This is also a big reason why we locked and
       * permission-checked the sequences beforehand.)
       */
      if (stmt->restart_seqs)
      {
            List     *options = list_make1(makeDefElem("restart", NULL));

            foreach(cell, seq_relids)
            {
                  Oid               seq_relid = lfirst_oid(cell);

                  AlterSequenceInternal(seq_relid, options);
            }
      }
}

/*
 * Check that a given rel is safe to truncate.  Subroutine for ExecuteTruncate
 */
static void
truncate_check_rel(Relation rel)
{
      AclResult   aclresult;

      /* Only allow truncate on regular tables */
      if (rel->rd_rel->relkind != RELKIND_RELATION)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a table",
                                    RelationGetRelationName(rel))));

      /* Permissions checks */
      aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
                                                  ACL_TRUNCATE);
      if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_CLASS,
                                 RelationGetRelationName(rel));

      if (!allowSystemTableMods && IsSystemRelation(rel))
            ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                         errmsg("permission denied: \"%s\" is a system catalog",
                                    RelationGetRelationName(rel))));

      /*
       * We can never allow truncation of shared or nailed-in-cache relations,
       * because we can't support changing their relfilenode values.
       */
      if (rel->rd_rel->relisshared || rel->rd_isnailed)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot truncate system relation \"%s\"",
                                    RelationGetRelationName(rel))));

      /*
       * Don't allow truncate on temp tables of other backends ... their local
       * buffer manager is not going to cope.
       */
      if (RELATION_IS_OTHER_TEMP(rel))
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                    errmsg("cannot truncate temporary tables of other sessions")));

      /*
       * Also check for active uses of the relation in the current transaction,
       * including open scans and pending AFTER trigger events.
       */
      CheckTableNotInUse(rel, "TRUNCATE");
}

/*----------
 * MergeAttributes
 *          Returns new schema given initial schema and superclasses.
 *
 * Input arguments:
 * 'schema' is the column/attribute definition for the table. (It's a list
 *          of ColumnDef's.) It is destructively changed.
 * 'supers' is a list of names (as RangeVar nodes) of parent relations.
 * 'istemp' is TRUE if we are creating a temp relation.
 *
 * Output arguments:
 * 'supOids' receives a list of the OIDs of the parent relations.
 * 'supconstr' receives a list of constraints belonging to the parents,
 *          updated as necessary to be valid for the child.
 * 'supOidCount' is set to the number of parents that have OID columns.
 *
 * Return value:
 * Completed schema list.
 *
 * Notes:
 *      The order in which the attributes are inherited is very important.
 *      Intuitively, the inherited attributes should come first. If a table
 *      inherits from multiple parents, the order of those attributes are
 *      according to the order of the parents specified in CREATE TABLE.
 *
 *      Here's an example:
 *
 *          create table person (name text, age int4, location point);
 *          create table emp (salary int4, manager text) inherits(person);
 *          create table student (gpa float8) inherits (person);
 *          create table stud_emp (percent int4) inherits (emp, student);
 *
 *      The order of the attributes of stud_emp is:
 *
 *                                        person {1:name, 2:age, 3:location}
 *                                        /      \
 *                   {6:gpa}  student   emp {4:salary, 5:manager}
 *                                        \      /
 *                                     stud_emp {7:percent}
 *
 *       If the same attribute name appears multiple times, then it appears
 *       in the result table in the proper location for its first appearance.
 *
 *       Constraints (including NOT NULL constraints) for the child table
 *       are the union of all relevant constraints, from both the child schema
 *       and parent tables.
 *
 *       The default value for a child column is defined as:
 *          (1) If the child schema specifies a default, that value is used.
 *          (2) If neither the child nor any parent specifies a default, then
 *                the column will not have a default.
 *          (3) If conflicting defaults are inherited from different parents
 *                (and not overridden by the child), an error is raised.
 *          (4) Otherwise the inherited default is used.
 *          Rule (3) is new in Postgres 7.1; in earlier releases you got a
 *          rather arbitrary choice of which parent default to use.
 *----------
 */
static List *
MergeAttributes(List *schema, List *supers, bool istemp,
                        List **supOids, List **supconstr, int *supOidCount)
{
      ListCell   *entry;
      List     *inhSchema = NIL;
      List     *parentOids = NIL;
      List     *constraints = NIL;
      int               parentsWithOids = 0;
      bool        have_bogus_defaults = false;
      char     *bogus_marker = "Bogus!";        /* marks conflicting defaults */
      int               child_attno;

      /*
       * Check for and reject tables with too many columns. We perform this
       * check relatively early for two reasons: (a) we don't run the risk of
       * overflowing an AttrNumber in subsequent code (b) an O(n^2) algorithm is
       * okay if we're processing <= 1600 columns, but could take minutes to
       * execute if the user attempts to create a table with hundreds of
       * thousands of columns.
       *
       * Note that we also need to check that any we do not exceed this figure
       * after including columns from inherited relations.
       */
      if (list_length(schema) > MaxHeapAttributeNumber)
            ereport(ERROR,
                        (errcode(ERRCODE_TOO_MANY_COLUMNS),
                         errmsg("tables can have at most %d columns",
                                    MaxHeapAttributeNumber)));

      /*
       * Check for duplicate names in the explicit list of attributes.
       *
       * Although we might consider merging such entries in the same way that we
       * handle name conflicts for inherited attributes, it seems to make more
       * sense to assume such conflicts are errors.
       */
      foreach(entry, schema)
      {
            ColumnDef  *coldef = lfirst(entry);
            ListCell   *rest;

            for_each_cell(rest, lnext(entry))
            {
                  ColumnDef  *restdef = lfirst(rest);

                  if (strcmp(coldef->colname, restdef->colname) == 0)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DUPLICATE_COLUMN),
                                     errmsg("column \"%s\" specified more than once",
                                                coldef->colname)));
            }
      }

      /*
       * Scan the parents left-to-right, and merge their attributes to form a
       * list of inherited attributes (inhSchema).  Also check to see if we need
       * to inherit an OID column.
       */
      child_attno = 0;
      foreach(entry, supers)
      {
            RangeVar   *parent = (RangeVar *) lfirst(entry);
            Relation    relation;
            TupleDesc   tupleDesc;
            TupleConstr *constr;
            AttrNumber *newattno;
            AttrNumber  parent_attno;

            relation = heap_openrv(parent, AccessShareLock);

            if (relation->rd_rel->relkind != RELKIND_RELATION)
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("inherited relation \"%s\" is not a table",
                                          parent->relname)));
            /* Permanent rels cannot inherit from temporary ones */
            if (!istemp && relation->rd_istemp)
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("cannot inherit from temporary relation \"%s\"",
                                          parent->relname)));

            /*
             * We should have an UNDER permission flag for this, but for now,
             * demand that creator of a child table own the parent.
             */
            if (!pg_class_ownercheck(RelationGetRelid(relation), GetUserId()))
                  aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                       RelationGetRelationName(relation));

            /*
             * Reject duplications in the list of parents.
             */
            if (list_member_oid(parentOids, RelationGetRelid(relation)))
                  ereport(ERROR,
                              (errcode(ERRCODE_DUPLICATE_TABLE),
                   errmsg("relation \"%s\" would be inherited from more than once",
                              parent->relname)));

            parentOids = lappend_oid(parentOids, RelationGetRelid(relation));

            if (relation->rd_rel->relhasoids)
                  parentsWithOids++;

            tupleDesc = RelationGetDescr(relation);
            constr = tupleDesc->constr;

            /*
             * newattno[] will contain the child-table attribute numbers for the
             * attributes of this parent table.  (They are not the same for
             * parents after the first one, nor if we have dropped columns.)
             */
            newattno = (AttrNumber *)
                  palloc(tupleDesc->natts * sizeof(AttrNumber));

            for (parent_attno = 1; parent_attno <= tupleDesc->natts;
                   parent_attno++)
            {
                  Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
                  char     *attributeName = NameStr(attribute->attname);
                  int               exist_attno;
                  ColumnDef  *def;

                  /*
                   * Ignore dropped columns in the parent.
                   */
                  if (attribute->attisdropped)
                  {
                        /*
                         * change_varattnos_of_a_node asserts that this is greater
                         * than zero, so if anything tries to use it, we should find
                         * out.
                         */
                        newattno[parent_attno - 1] = 0;
                        continue;
                  }

                  /*
                   * Does it conflict with some previously inherited column?
                   */
                  exist_attno = findAttrByName(attributeName, inhSchema);
                  if (exist_attno > 0)
                  {
                        Oid               defTypeId;
                        int32       deftypmod;

                        /*
                         * Yes, try to merge the two column definitions. They must
                         * have the same type and typmod.
                         */
                        ereport(NOTICE,
                                    (errmsg("merging multiple inherited definitions of column \"%s\"",
                                                attributeName)));
                        def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
                        defTypeId = typenameTypeId(NULL, def->typename, &deftypmod);
                        if (defTypeId != attribute->atttypid ||
                              deftypmod != attribute->atttypmod)
                              ereport(ERROR,
                                          (errcode(ERRCODE_DATATYPE_MISMATCH),
                                    errmsg("inherited column \"%s\" has a type conflict",
                                             attributeName),
                                           errdetail("%s versus %s",
                                                         TypeNameToString(def->typename),
                                                         format_type_be(attribute->atttypid))));
                        def->inhcount++;
                        /* Merge of NOT NULL constraints = OR 'em together */
                        def->is_not_null |= attribute->attnotnull;
                        /* Default and other constraints are handled below */
                        newattno[parent_attno - 1] = exist_attno;
                  }
                  else
                  {
                        /*
                         * No, create a new inherited column
                         */
                        def = makeNode(ColumnDef);
                        def->colname = pstrdup(attributeName);
                        def->typename = makeTypeNameFromOid(attribute->atttypid,
                                                                              attribute->atttypmod);
                        def->inhcount = 1;
                        def->is_local = false;
                        def->is_not_null = attribute->attnotnull;
                        def->raw_default = NULL;
                        def->cooked_default = NULL;
                        def->constraints = NIL;
                        inhSchema = lappend(inhSchema, def);
                        newattno[parent_attno - 1] = ++child_attno;
                  }

                  /*
                   * Copy default if any
                   */
                  if (attribute->atthasdef)
                  {
                        char     *this_default = NULL;
                        AttrDefault *attrdef;
                        int               i;

                        /* Find default in constraint structure */
                        Assert(constr != NULL);
                        attrdef = constr->defval;
                        for (i = 0; i < constr->num_defval; i++)
                        {
                              if (attrdef[i].adnum == parent_attno)
                              {
                                    this_default = attrdef[i].adbin;
                                    break;
                              }
                        }
                        Assert(this_default != NULL);

                        /*
                         * If default expr could contain any vars, we'd need to fix
                         * 'em, but it can't; so default is ready to apply to child.
                         *
                         * If we already had a default from some prior parent, check
                         * to see if they are the same.  If so, no problem; if not,
                         * mark the column as having a bogus default. Below, we will
                         * complain if the bogus default isn't overridden by the child
                         * schema.
                         */
                        Assert(def->raw_default == NULL);
                        if (def->cooked_default == NULL)
                              def->cooked_default = pstrdup(this_default);
                        else if (strcmp(def->cooked_default, this_default) != 0)
                        {
                              def->cooked_default = bogus_marker;
                              have_bogus_defaults = true;
                        }
                  }
            }

            /*
             * Now copy the CHECK constraints of this parent, adjusting attnos
             * using the completed newattno[] map.    Identically named constraints
             * are merged if possible, else we throw error.
             */
            if (constr && constr->num_check > 0)
            {
                  ConstrCheck *check = constr->check;
                  int               i;

                  for (i = 0; i < constr->num_check; i++)
                  {
                        char     *name = check[i].ccname;
                        Node     *expr;

                        /* adjust varattnos of ccbin here */
                        expr = stringToNode(check[i].ccbin);
                        change_varattnos_of_a_node(expr, newattno);

                        /* check for duplicate */
                        if (!MergeCheckConstraint(constraints, name, expr))
                        {
                              /* nope, this is a new one */
                              CookedConstraint *cooked;

                              cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
                              cooked->contype = CONSTR_CHECK;
                              cooked->name = pstrdup(name);
                              cooked->attnum = 0; /* not used for constraints */
                              cooked->expr = expr;
                              cooked->is_local = false;
                              cooked->inhcount = 1;
                              constraints = lappend(constraints, cooked);
                        }
                  }
            }

            pfree(newattno);

            /*
             * Close the parent rel, but keep our AccessShareLock on it until xact
             * commit.  That will prevent someone else from deleting or ALTERing
             * the parent before the child is committed.
             */
            heap_close(relation, NoLock);
      }

      /*
       * If we had no inherited attributes, the result schema is just the
       * explicitly declared columns.  Otherwise, we need to merge the declared
       * columns into the inherited schema list.
       */
      if (inhSchema != NIL)
      {
            foreach(entry, schema)
            {
                  ColumnDef  *newdef = lfirst(entry);
                  char     *attributeName = newdef->colname;
                  int               exist_attno;

                  /*
                   * Does it conflict with some previously inherited column?
                   */
                  exist_attno = findAttrByName(attributeName, inhSchema);
                  if (exist_attno > 0)
                  {
                        ColumnDef  *def;
                        Oid               defTypeId,
                                          newTypeId;
                        int32       deftypmod,
                                          newtypmod;

                        /*
                         * Yes, try to merge the two column definitions. They must
                         * have the same type and typmod.
                         */
                        ereport(NOTICE,
                           (errmsg("merging column \"%s\" with inherited definition",
                                       attributeName)));
                        def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
                        defTypeId = typenameTypeId(NULL, def->typename, &deftypmod);
                        newTypeId = typenameTypeId(NULL, newdef->typename, &newtypmod);
                        if (defTypeId != newTypeId || deftypmod != newtypmod)
                              ereport(ERROR,
                                          (errcode(ERRCODE_DATATYPE_MISMATCH),
                                           errmsg("column \"%s\" has a type conflict",
                                                      attributeName),
                                           errdetail("%s versus %s",
                                                         TypeNameToString(def->typename),
                                                         TypeNameToString(newdef->typename))));
                        /* Mark the column as locally defined */
                        def->is_local = true;
                        /* Merge of NOT NULL constraints = OR 'em together */
                        def->is_not_null |= newdef->is_not_null;
                        /* If new def has a default, override previous default */
                        if (newdef->raw_default != NULL)
                        {
                              def->raw_default = newdef->raw_default;
                              def->cooked_default = newdef->cooked_default;
                        }
                  }
                  else
                  {
                        /*
                         * No, attach new column to result schema
                         */
                        inhSchema = lappend(inhSchema, newdef);
                  }
            }

            schema = inhSchema;

            /*
             * Check that we haven't exceeded the legal # of columns after merging
             * in inherited columns.
             */
            if (list_length(schema) > MaxHeapAttributeNumber)
                  ereport(ERROR,
                              (errcode(ERRCODE_TOO_MANY_COLUMNS),
                               errmsg("tables can have at most %d columns",
                                          MaxHeapAttributeNumber)));
      }

      /*
       * If we found any conflicting parent default values, check to make sure
       * they were overridden by the child.
       */
      if (have_bogus_defaults)
      {
            foreach(entry, schema)
            {
                  ColumnDef  *def = lfirst(entry);

                  if (def->cooked_default == bogus_marker)
                        ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
                          errmsg("column \"%s\" inherits conflicting default values",
                                     def->colname),
                                     errhint("To resolve the conflict, specify a default explicitly.")));
            }
      }

      *supOids = parentOids;
      *supconstr = constraints;
      *supOidCount = parentsWithOids;
      return schema;
}


/*
 * MergeCheckConstraint
 *          Try to merge an inherited CHECK constraint with previous ones
 *
 * If we inherit identically-named constraints from multiple parents, we must
 * merge them, or throw an error if they don't have identical definitions.
 *
 * constraints is a list of CookedConstraint structs for previous constraints.
 *
 * Returns TRUE if merged (constraint is a duplicate), or FALSE if it's
 * got a so-far-unique name, or throws error if conflict.
 */
static bool
MergeCheckConstraint(List *constraints, char *name, Node *expr)
{
      ListCell   *lc;

      foreach(lc, constraints)
      {
            CookedConstraint *ccon = (CookedConstraint *) lfirst(lc);

            Assert(ccon->contype == CONSTR_CHECK);

            /* Non-matching names never conflict */
            if (strcmp(ccon->name, name) != 0)
                  continue;

            if (equal(expr, ccon->expr))
            {
                  /* OK to merge */
                  ccon->inhcount++;
                  return true;
            }

            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_OBJECT),
                         errmsg("check constraint name \"%s\" appears multiple times but with different expressions",
                                    name)));
      }

      return false;
}


/*
 * Replace varattno values in an expression tree according to the given
 * map array, that is, varattno N is replaced by newattno[N-1].  It is
 * caller's responsibility to ensure that the array is long enough to
 * define values for all user varattnos present in the tree.  System column
 * attnos remain unchanged.
 *
 * Note that the passed node tree is modified in-place!
 */
void
change_varattnos_of_a_node(Node *node, const AttrNumber *newattno)
{
      /* no setup needed, so away we go */
      (void) change_varattnos_walker(node, newattno);
}

static bool
change_varattnos_walker(Node *node, const AttrNumber *newattno)
{
      if (node == NULL)
            return false;
      if (IsA(node, Var))
      {
            Var            *var = (Var *) node;

            if (var->varlevelsup == 0 && var->varno == 1 &&
                  var->varattno > 0)
            {
                  /*
                   * ??? the following may be a problem when the node is multiply
                   * referenced though stringToNode() doesn't create such a node
                   * currently.
                   */
                  Assert(newattno[var->varattno - 1] > 0);
                  var->varattno = var->varoattno = newattno[var->varattno - 1];
            }
            return false;
      }
      return expression_tree_walker(node, change_varattnos_walker,
                                                  (void *) newattno);
}

/*
 * Generate a map for change_varattnos_of_a_node from old and new TupleDesc's,
 * matching according to column name.
 */
AttrNumber *
varattnos_map(TupleDesc old, TupleDesc new)
{
      AttrNumber *attmap;
      int               i,
                        j;

      attmap = (AttrNumber *) palloc0(sizeof(AttrNumber) * old->natts);
      for (i = 1; i <= old->natts; i++)
      {
            if (old->attrs[i - 1]->attisdropped)
                  continue;               /* leave the entry as zero */

            for (j = 1; j <= new->natts; j++)
            {
                  if (strcmp(NameStr(old->attrs[i - 1]->attname),
                                 NameStr(new->attrs[j - 1]->attname)) == 0)
                  {
                        attmap[i - 1] = j;
                        break;
                  }
            }
      }
      return attmap;
}

/*
 * Generate a map for change_varattnos_of_a_node from a TupleDesc and a list
 * of ColumnDefs
 */
AttrNumber *
varattnos_map_schema(TupleDesc old, List *schema)
{
      AttrNumber *attmap;
      int               i;

      attmap = (AttrNumber *) palloc0(sizeof(AttrNumber) * old->natts);
      for (i = 1; i <= old->natts; i++)
      {
            if (old->attrs[i - 1]->attisdropped)
                  continue;               /* leave the entry as zero */

            attmap[i - 1] = findAttrByName(NameStr(old->attrs[i - 1]->attname),
                                                         schema);
      }
      return attmap;
}


/*
 * StoreCatalogInheritance
 *          Updates the system catalogs with proper inheritance information.
 *
 * supers is a list of the OIDs of the new relation's direct ancestors.
 */
static void
StoreCatalogInheritance(Oid relationId, List *supers)
{
      Relation    relation;
      int16       seqNumber;
      ListCell   *entry;

      /*
       * sanity checks
       */
      AssertArg(OidIsValid(relationId));

      if (supers == NIL)
            return;

      /*
       * Store INHERITS information in pg_inherits using direct ancestors only.
       * Also enter dependencies on the direct ancestors, and make sure they are
       * marked with relhassubclass = true.
       *
       * (Once upon a time, both direct and indirect ancestors were found here
       * and then entered into pg_ipl.  Since that catalog doesn't exist
       * anymore, there's no need to look for indirect ancestors.)
       */
      relation = heap_open(InheritsRelationId, RowExclusiveLock);

      seqNumber = 1;
      foreach(entry, supers)
      {
            Oid               parentOid = lfirst_oid(entry);

            StoreCatalogInheritance1(relationId, parentOid, seqNumber, relation);
            seqNumber++;
      }

      heap_close(relation, RowExclusiveLock);
}

/*
 * Make catalog entries showing relationId as being an inheritance child
 * of parentOid.  inhRelation is the already-opened pg_inherits catalog.
 */
static void
StoreCatalogInheritance1(Oid relationId, Oid parentOid,
                                     int16 seqNumber, Relation inhRelation)
{
      TupleDesc   desc = RelationGetDescr(inhRelation);
      Datum       datum[Natts_pg_inherits];
      bool        nullarr[Natts_pg_inherits];
      ObjectAddress childobject,
                        parentobject;
      HeapTuple   tuple;

      /*
       * Make the pg_inherits entry
       */
      datum[0] = ObjectIdGetDatum(relationId);  /* inhrelid */
      datum[1] = ObjectIdGetDatum(parentOid);         /* inhparent */
      datum[2] = Int16GetDatum(seqNumber);            /* inhseqno */

      nullarr[0] = false;
      nullarr[1] = false;
      nullarr[2] = false;

      tuple = heap_form_tuple(desc, datum, nullarr);

      simple_heap_insert(inhRelation, tuple);

      CatalogUpdateIndexes(inhRelation, tuple);

      heap_freetuple(tuple);

      /*
       * Store a dependency too
       */
      parentobject.classId = RelationRelationId;
      parentobject.objectId = parentOid;
      parentobject.objectSubId = 0;
      childobject.classId = RelationRelationId;
      childobject.objectId = relationId;
      childobject.objectSubId = 0;

      recordDependencyOn(&childobject, &parentobject, DEPENDENCY_NORMAL);

      /*
       * Mark the parent as having subclasses.
       */
      setRelhassubclassInRelation(parentOid, true);
}

/*
 * Look for an existing schema entry with the given name.
 *
 * Returns the index (starting with 1) if attribute already exists in schema,
 * 0 if it doesn't.
 */
static int
findAttrByName(const char *attributeName, List *schema)
{
      ListCell   *s;
      int               i = 1;

      foreach(s, schema)
      {
            ColumnDef  *def = lfirst(s);

            if (strcmp(attributeName, def->colname) == 0)
                  return i;

            i++;
      }
      return 0;
}

/*
 * Update a relation's pg_class.relhassubclass entry to the given value
 */
static void
setRelhassubclassInRelation(Oid relationId, bool relhassubclass)
{
      Relation    relationRelation;
      HeapTuple   tuple;
      Form_pg_class classtuple;

      /*
       * Fetch a modifiable copy of the tuple, modify it, update pg_class.
       *
       * If the tuple already has the right relhassubclass setting, we don't
       * need to update it, but we still need to issue an SI inval message.
       */
      relationRelation = heap_open(RelationRelationId, RowExclusiveLock);
      tuple = SearchSysCacheCopy(RELOID,
                                             ObjectIdGetDatum(relationId),
                                             0, 0, 0);
      if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", relationId);
      classtuple = (Form_pg_class) GETSTRUCT(tuple);

      if (classtuple->relhassubclass != relhassubclass)
      {
            classtuple->relhassubclass = relhassubclass;
            simple_heap_update(relationRelation, &tuple->t_self, tuple);

            /* keep the catalog indexes up to date */
            CatalogUpdateIndexes(relationRelation, tuple);
      }
      else
      {
            /* no need to change tuple, but force relcache rebuild anyway */
            CacheInvalidateRelcacheByTuple(tuple);
      }

      heap_freetuple(tuple);
      heap_close(relationRelation, RowExclusiveLock);
}


/*
 *          renameatt         - changes the name of a attribute in a relation
 *
 *          Attname attribute is changed in attribute catalog.
 *          No record of the previous attname is kept (correct?).
 *
 *          get proper relrelation from relation catalog (if not arg)
 *          scan attribute catalog
 *                      for name conflict (within rel)
 *                      for original attribute (if not arg)
 *          modify attname in attribute tuple
 *          insert modified attribute in attribute catalog
 *          delete original attribute from attribute catalog
 */
void
renameatt(Oid myrelid,
              const char *oldattname,
              const char *newattname,
              bool recurse,
              bool recursing)
{
      Relation    targetrelation;
      Relation    attrelation;
      HeapTuple   atttup;
      Form_pg_attribute attform;
      int               attnum;
      List     *indexoidlist;
      ListCell   *indexoidscan;

      /*
       * Grab an exclusive lock on the target table, which we will NOT release
       * until end of transaction.
       */
      targetrelation = relation_open(myrelid, AccessExclusiveLock);

      /*
       * permissions checking.  this would normally be done in utility.c, but
       * this particular routine is recursive.
       *
       * normally, only the owner of a class can change its schema.
       */
      if (!pg_class_ownercheck(myrelid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 RelationGetRelationName(targetrelation));
      if (!allowSystemTableMods && IsSystemRelation(targetrelation))
            ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                         errmsg("permission denied: \"%s\" is a system catalog",
                                    RelationGetRelationName(targetrelation))));

      /*
       * if the 'recurse' flag is set then we are supposed to rename this
       * attribute in all classes that inherit from 'relname' (as well as in
       * 'relname').
       *
       * any permissions or problems with duplicate attributes will cause the
       * whole transaction to abort, which is what we want -- all or nothing.
       */
      if (recurse)
      {
            ListCell   *child;
            List     *children;

            children = find_all_inheritors(myrelid, AccessExclusiveLock);

            /*
             * find_all_inheritors does the recursive search of the inheritance
             * hierarchy, so all we have to do is process all of the relids in the
             * list that it returns.
             */
            foreach(child, children)
            {
                  Oid               childrelid = lfirst_oid(child);

                  if (childrelid == myrelid)
                        continue;
                  /* note we need not recurse again */
                  renameatt(childrelid, oldattname, newattname, false, true);
            }
      }
      else
      {
            /*
             * If we are told not to recurse, there had better not be any child
             * tables; else the rename would put them out of step.
             */
            if (!recursing &&
                  find_inheritance_children(myrelid, NoLock) != NIL)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("inherited column \"%s\" must be renamed in child tables too",
                                          oldattname)));
      }

      attrelation = heap_open(AttributeRelationId, RowExclusiveLock);

      atttup = SearchSysCacheCopyAttName(myrelid, oldattname);
      if (!HeapTupleIsValid(atttup))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" does not exist",
                                    oldattname)));
      attform = (Form_pg_attribute) GETSTRUCT(atttup);

      attnum = attform->attnum;
      if (attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot rename system column \"%s\"",
                                    oldattname)));

      /*
       * if the attribute is inherited, forbid the renaming, unless we are
       * already inside a recursive rename.
       */
      if (attform->attinhcount > 0 && !recursing)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("cannot rename inherited column \"%s\"",
                                    oldattname)));

      /* should not already exist */
      /* this test is deliberately not attisdropped-aware */
      if (SearchSysCacheExists(ATTNAME,
                                           ObjectIdGetDatum(myrelid),
                                           PointerGetDatum(newattname),
                                           0, 0))
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" already exists",
                                newattname, RelationGetRelationName(targetrelation))));

      namestrcpy(&(attform->attname), newattname);

      simple_heap_update(attrelation, &atttup->t_self, atttup);

      /* keep system catalog indexes current */
      CatalogUpdateIndexes(attrelation, atttup);

      heap_freetuple(atttup);

      /*
       * Update column names of indexes that refer to the column being renamed.
       */
      indexoidlist = RelationGetIndexList(targetrelation);

      foreach(indexoidscan, indexoidlist)
      {
            Oid               indexoid = lfirst_oid(indexoidscan);
            HeapTuple   indextup;
            Form_pg_index indexform;
            int               i;

            /*
             * Scan through index columns to see if there's any simple index
             * entries for this attribute.      We ignore expressional entries.
             */
            indextup = SearchSysCache(INDEXRELID,
                                                  ObjectIdGetDatum(indexoid),
                                                  0, 0, 0);
            if (!HeapTupleIsValid(indextup))
                  elog(ERROR, "cache lookup failed for index %u", indexoid);
            indexform = (Form_pg_index) GETSTRUCT(indextup);

            for (i = 0; i < indexform->indnatts; i++)
            {
                  if (attnum != indexform->indkey.values[i])
                        continue;

                  /*
                   * Found one, rename it.
                   */
                  atttup = SearchSysCacheCopy(ATTNUM,
                                                            ObjectIdGetDatum(indexoid),
                                                            Int16GetDatum(i + 1),
                                                            0, 0);
                  if (!HeapTupleIsValid(atttup))
                        continue;         /* should we raise an error? */

                  /*
                   * Update the (copied) attribute tuple.
                   */
                  namestrcpy(&(((Form_pg_attribute) GETSTRUCT(atttup))->attname),
                                 newattname);

                  simple_heap_update(attrelation, &atttup->t_self, atttup);

                  /* keep system catalog indexes current */
                  CatalogUpdateIndexes(attrelation, atttup);

                  heap_freetuple(atttup);
            }

            ReleaseSysCache(indextup);
      }

      list_free(indexoidlist);

      heap_close(attrelation, RowExclusiveLock);

      relation_close(targetrelation, NoLock);         /* close rel but keep lock */
}


/*
 * Execute ALTER TABLE/INDEX/SEQUENCE/VIEW RENAME
 *
 * Caller has already done permissions checks.
 */
void
RenameRelation(Oid myrelid, const char *newrelname, ObjectType reltype)
{
      Relation    targetrelation;
      Oid               namespaceId;
      char        relkind;

      /*
       * Grab an exclusive lock on the target table, index, sequence or view,
       * which we will NOT release until end of transaction.
       */
      targetrelation = relation_open(myrelid, AccessExclusiveLock);

      namespaceId = RelationGetNamespace(targetrelation);
      relkind = targetrelation->rd_rel->relkind;

      /*
       * For compatibility with prior releases, we don't complain if ALTER TABLE
       * or ALTER INDEX is used to rename a sequence or view.
       */
      if (reltype == OBJECT_SEQUENCE && relkind != RELKIND_SEQUENCE)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a sequence",
                                    RelationGetRelationName(targetrelation))));

      if (reltype == OBJECT_VIEW && relkind != RELKIND_VIEW)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a view",
                                    RelationGetRelationName(targetrelation))));

      /*
       * Don't allow ALTER TABLE on composite types. We want people to use ALTER
       * TYPE for that.
       */
      if (relkind == RELKIND_COMPOSITE_TYPE)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is a composite type",
                                    RelationGetRelationName(targetrelation)),
                         errhint("Use ALTER TYPE instead.")));

      /* Do the work */
      RenameRelationInternal(myrelid, newrelname, namespaceId);

      /*
       * Close rel, but keep exclusive lock!
       */
      relation_close(targetrelation, NoLock);
}

/*
 *          RenameRelationInternal - change the name of a relation
 *
 *          XXX - When renaming sequences, we don't bother to modify the
 *                  sequence name that is stored within the sequence itself
 *                  (this would cause problems with MVCC). In the future,
 *                  the sequence name should probably be removed from the
 *                  sequence, AFAIK there's no need for it to be there.
 */
void
RenameRelationInternal(Oid myrelid, const char *newrelname, Oid namespaceId)
{
      Relation    targetrelation;
      Relation    relrelation;      /* for RELATION relation */
      HeapTuple   reltup;
      Form_pg_class relform;

      /*
       * Grab an exclusive lock on the target table, index, sequence or view,
       * which we will NOT release until end of transaction.
       */
      targetrelation = relation_open(myrelid, AccessExclusiveLock);

      /*
       * Find relation's pg_class tuple, and make sure newrelname isn't in use.
       */
      relrelation = heap_open(RelationRelationId, RowExclusiveLock);

      reltup = SearchSysCacheCopy(RELOID,
                                                ObjectIdGetDatum(myrelid),
                                                0, 0, 0);
      if (!HeapTupleIsValid(reltup))            /* shouldn't happen */
            elog(ERROR, "cache lookup failed for relation %u", myrelid);
      relform = (Form_pg_class) GETSTRUCT(reltup);

      if (get_relname_relid(newrelname, namespaceId) != InvalidOid)
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_TABLE),
                         errmsg("relation \"%s\" already exists",
                                    newrelname)));

      /*
       * Update pg_class tuple with new relname.      (Scribbling on reltup is OK
       * because it's a copy...)
       */
      namestrcpy(&(relform->relname), newrelname);

      simple_heap_update(relrelation, &reltup->t_self, reltup);

      /* keep the system catalog indexes current */
      CatalogUpdateIndexes(relrelation, reltup);

      heap_freetuple(reltup);
      heap_close(relrelation, RowExclusiveLock);

      /*
       * Also rename the associated type, if any.
       */
      if (OidIsValid(targetrelation->rd_rel->reltype))
            RenameTypeInternal(targetrelation->rd_rel->reltype,
                                       newrelname, namespaceId);

      /*
       * Also rename the associated constraint, if any.
       */
      if (targetrelation->rd_rel->relkind == RELKIND_INDEX)
      {
            Oid               constraintId = get_index_constraint(myrelid);

            if (OidIsValid(constraintId))
                  RenameConstraintById(constraintId, newrelname);
      }

      /*
       * Close rel, but keep exclusive lock!
       */
      relation_close(targetrelation, NoLock);
}

/*
 * Disallow ALTER TABLE (and similar commands) when the current backend has
 * any open reference to the target table besides the one just acquired by
 * the calling command; this implies there's an open cursor or active plan.
 * We need this check because our AccessExclusiveLock doesn't protect us
 * against stomping on our own foot, only other people's feet!
 *
 * For ALTER TABLE, the only case known to cause serious trouble is ALTER
 * COLUMN TYPE, and some changes are obviously pretty benign, so this could
 * possibly be relaxed to only error out for certain types of alterations.
 * But the use-case for allowing any of these things is not obvious, so we
 * won't work hard at it for now.
 *
 * We also reject these commands if there are any pending AFTER trigger events
 * for the rel.  This is certainly necessary for the rewriting variants of
 * ALTER TABLE, because they don't preserve tuple TIDs and so the pending
 * events would try to fetch the wrong tuples.  It might be overly cautious
 * in other cases, but again it seems better to err on the side of paranoia.
 *
 * REINDEX calls this with "rel" referencing the index to be rebuilt; here
 * we are worried about active indexscans on the index.  The trigger-event
 * check can be skipped, since we are doing no damage to the parent table.
 *
 * The statement name (eg, "ALTER TABLE") is passed for use in error messages.
 */
void
CheckTableNotInUse(Relation rel, const char *stmt)
{
      int               expected_refcnt;

      expected_refcnt = rel->rd_isnailed ? 2 : 1;
      if (rel->rd_refcnt != expected_refcnt)
            ereport(ERROR,
                        (errcode(ERRCODE_OBJECT_IN_USE),
            /* translator: first %s is a SQL command, eg ALTER TABLE */
                         errmsg("cannot %s \"%s\" because "
                                    "it is being used by active queries in this session",
                                    stmt, RelationGetRelationName(rel))));

      if (rel->rd_rel->relkind != RELKIND_INDEX &&
            AfterTriggerPendingOnRel(RelationGetRelid(rel)))
            ereport(ERROR,
                        (errcode(ERRCODE_OBJECT_IN_USE),
            /* translator: first %s is a SQL command, eg ALTER TABLE */
                         errmsg("cannot %s \"%s\" because "
                                    "it has pending trigger events",
                                    stmt, RelationGetRelationName(rel))));
}

/*
 * AlterTable
 *          Execute ALTER TABLE, which can be a list of subcommands
 *
 * ALTER TABLE is performed in three phases:
 *          1. Examine subcommands and perform pre-transformation checking.
 *          2. Update system catalogs.
 *          3. Scan table(s) to check new constraints, and optionally recopy
 *             the data into new table(s).
 * Phase 3 is not performed unless one or more of the subcommands requires
 * it.      The intention of this design is to allow multiple independent
 * updates of the table schema to be performed with only one pass over the
 * data.
 *
 * ATPrepCmd performs phase 1.      A "work queue" entry is created for
 * each table to be affected (there may be multiple affected tables if the
 * commands traverse a table inheritance hierarchy).  Also we do preliminary
 * validation of the subcommands, including parse transformation of those
 * expressions that need to be evaluated with respect to the old table
 * schema.
 *
 * ATRewriteCatalogs performs phase 2 for each affected table.    (Note that
 * phases 2 and 3 normally do no explicit recursion, since phase 1 already
 * did it --- although some subcommands have to recurse in phase 2 instead.)
 * Certain subcommands need to be performed before others to avoid
 * unnecessary conflicts; for example, DROP COLUMN should come before
 * ADD COLUMN.    Therefore phase 1 divides the subcommands into multiple
 * lists, one for each logical "pass" of phase 2.
 *
 * ATRewriteTables performs phase 3 for those tables that need it.
 *
 * Thanks to the magic of MVCC, an error anywhere along the way rolls back
 * the whole operation; we don't have to do anything special to clean up.
 */
void
AlterTable(AlterTableStmt *stmt)
{
      Relation    rel = relation_openrv(stmt->relation, AccessExclusiveLock);

      CheckTableNotInUse(rel, "ALTER TABLE");

      /* Check relation type against type specified in the ALTER command */
      switch (stmt->relkind)
      {
            case OBJECT_TABLE:

                  /*
                   * For mostly-historical reasons, we allow ALTER TABLE to apply to
                   * all relation types.
                   */
                  break;

            case OBJECT_INDEX:
                  if (rel->rd_rel->relkind != RELKIND_INDEX)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not an index",
                                                RelationGetRelationName(rel))));
                  break;

            case OBJECT_SEQUENCE:
                  if (rel->rd_rel->relkind != RELKIND_SEQUENCE)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not a sequence",
                                                RelationGetRelationName(rel))));
                  break;

            case OBJECT_VIEW:
                  if (rel->rd_rel->relkind != RELKIND_VIEW)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not a view",
                                                RelationGetRelationName(rel))));
                  break;

            default:
                  elog(ERROR, "unrecognized object type: %d", (int) stmt->relkind);
      }

      ATController(rel, stmt->cmds, interpretInhOption(stmt->relation->inhOpt));
}

/*
 * AlterTableInternal
 *
 * ALTER TABLE with target specified by OID
 *
 * We do not reject if the relation is already open, because it's quite
 * likely that one or more layers of caller have it open.  That means it
 * is unsafe to use this entry point for alterations that could break
 * existing query plans.  On the assumption it's not used for such, we
 * don't have to reject pending AFTER triggers, either.
 */
void
AlterTableInternal(Oid relid, List *cmds, bool recurse)
{
      Relation    rel = relation_open(relid, AccessExclusiveLock);

      ATController(rel, cmds, recurse);
}

static void
ATController(Relation rel, List *cmds, bool recurse)
{
      List     *wqueue = NIL;
      ListCell   *lcmd;

      /* Phase 1: preliminary examination of commands, create work queue */
      foreach(lcmd, cmds)
      {
            AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

            ATPrepCmd(&wqueue, rel, cmd, recurse, false);
      }

      /* Close the relation, but keep lock until commit */
      relation_close(rel, NoLock);

      /* Phase 2: update system catalogs */
      ATRewriteCatalogs(&wqueue);

      /* Phase 3: scan/rewrite tables as needed */
      ATRewriteTables(&wqueue);
}

/*
 * ATPrepCmd
 *
 * Traffic cop for ALTER TABLE Phase 1 operations, including simple
 * recursion and permission checks.
 *
 * Caller must have acquired AccessExclusiveLock on relation already.
 * This lock should be held until commit.
 */
static void
ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
              bool recurse, bool recursing)
{
      AlteredTableInfo *tab;
      int               pass;

      /* Find or create work queue entry for this table */
      tab = ATGetQueueEntry(wqueue, rel);

      /*
       * Copy the original subcommand for each table.  This avoids conflicts
       * when different child tables need to make different parse
       * transformations (for example, the same column may have different column
       * numbers in different children).
       */
      cmd = copyObject(cmd);

      /*
       * Do permissions checking, recursion to child tables if needed, and any
       * additional phase-1 processing needed.
       */
      switch (cmd->subtype)
      {
            case AT_AddColumn:            /* ADD COLUMN */
                  ATSimplePermissions(rel, false);
                  /* Performs own recursion */
                  ATPrepAddColumn(wqueue, rel, recurse, cmd);
                  pass = AT_PASS_ADD_COL;
                  break;
            case AT_AddColumnToView:            /* add column via CREATE OR REPLACE
                                                             * VIEW */
                  ATSimplePermissions(rel, true);
                  /* Performs own recursion */
                  ATPrepAddColumn(wqueue, rel, recurse, cmd);
                  pass = AT_PASS_ADD_COL;
                  break;
            case AT_ColumnDefault:  /* ALTER COLUMN DEFAULT */

                  /*
                   * We allow defaults on views so that INSERT into a view can have
                   * default-ish behavior.  This works because the rewriter
                   * substitutes default values into INSERTs before it expands
                   * rules.
                   */
                  ATSimplePermissions(rel, true);
                  ATSimpleRecursion(wqueue, rel, cmd, recurse);
                  /* No command-specific prep needed */
                  pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
                  break;
            case AT_DropNotNull:    /* ALTER COLUMN DROP NOT NULL */
                  ATSimplePermissions(rel, false);
                  ATSimpleRecursion(wqueue, rel, cmd, recurse);
                  /* No command-specific prep needed */
                  pass = AT_PASS_DROP;
                  break;
            case AT_SetNotNull:           /* ALTER COLUMN SET NOT NULL */
                  ATSimplePermissions(rel, false);
                  ATSimpleRecursion(wqueue, rel, cmd, recurse);
                  /* No command-specific prep needed */
                  pass = AT_PASS_ADD_CONSTR;
                  break;
            case AT_SetStatistics:  /* ALTER COLUMN STATISTICS */
                  ATSimpleRecursion(wqueue, rel, cmd, recurse);
                  /* Performs own permission checks */
                  ATPrepSetStatistics(rel, cmd->name, cmd->def);
                  pass = AT_PASS_COL_ATTRS;
                  break;
            case AT_SetStorage:           /* ALTER COLUMN STORAGE */
                  ATSimplePermissions(rel, false);
                  ATSimpleRecursion(wqueue, rel, cmd, recurse);
                  /* No command-specific prep needed */
                  pass = AT_PASS_COL_ATTRS;
                  break;
            case AT_DropColumn:           /* DROP COLUMN */
                  ATSimplePermissions(rel, false);
                  /* Recursion occurs during execution phase */
                  /* No command-specific prep needed except saving recurse flag */
                  if (recurse)
                        cmd->subtype = AT_DropColumnRecurse;
                  pass = AT_PASS_DROP;
                  break;
            case AT_AddIndex:       /* ADD INDEX */
                  ATSimplePermissions(rel, false);
                  /* This command never recurses */
                  /* No command-specific prep needed */
                  pass = AT_PASS_ADD_INDEX;
                  break;
            case AT_AddConstraint:  /* ADD CONSTRAINT */
                  ATSimplePermissions(rel, false);
                  /* Recursion occurs during execution phase */
                  /* No command-specific prep needed except saving recurse flag */
                  if (recurse)
                        cmd->subtype = AT_AddConstraintRecurse;
                  pass = AT_PASS_ADD_CONSTR;
                  break;
            case AT_DropConstraint: /* DROP CONSTRAINT */
                  ATSimplePermissions(rel, false);
                  /* Recursion occurs during execution phase */
                  /* No command-specific prep needed except saving recurse flag */
                  if (recurse)
                        cmd->subtype = AT_DropConstraintRecurse;
                  pass = AT_PASS_DROP;
                  break;
            case AT_AlterColumnType:            /* ALTER COLUMN TYPE */
                  ATSimplePermissions(rel, false);
                  /* Performs own recursion */
                  ATPrepAlterColumnType(wqueue, tab, rel, recurse, recursing, cmd);
                  pass = AT_PASS_ALTER_TYPE;
                  break;
            case AT_ChangeOwner:    /* ALTER OWNER */
                  /* This command never recurses */
                  /* No command-specific prep needed */
                  pass = AT_PASS_MISC;
                  break;
            case AT_ClusterOn:            /* CLUSTER ON */
            case AT_DropCluster:    /* SET WITHOUT CLUSTER */
                  ATSimplePermissions(rel, false);
                  /* These commands never recurse */
                  /* No command-specific prep needed */
                  pass = AT_PASS_MISC;
                  break;
            case AT_AddOids:        /* SET WITH OIDS */
                  ATSimplePermissions(rel, false);
                  /* Performs own recursion */
                  if (!rel->rd_rel->relhasoids || recursing)
                        ATPrepAddOids(wqueue, rel, recurse, cmd);
                  pass = AT_PASS_ADD_COL;
                  break;
            case AT_DropOids:       /* SET WITHOUT OIDS */
                  ATSimplePermissions(rel, false);
                  /* Performs own recursion */
                  if (rel->rd_rel->relhasoids)
                  {
                        AlterTableCmd *dropCmd = makeNode(AlterTableCmd);

                        dropCmd->subtype = AT_DropColumn;
                        dropCmd->name = pstrdup("oid");
                        dropCmd->behavior = cmd->behavior;
                        ATPrepCmd(wqueue, rel, dropCmd, recurse, false);
                  }
                  pass = AT_PASS_DROP;
                  break;
            case AT_SetTableSpace:  /* SET TABLESPACE */
                  ATSimplePermissionsRelationOrIndex(rel);
                  /* This command never recurses */
                  ATPrepSetTableSpace(tab, rel, cmd->name);
                  pass = AT_PASS_MISC;    /* doesn't actually matter */
                  break;
            case AT_SetRelOptions:  /* SET (...) */
            case AT_ResetRelOptions:            /* RESET (...) */
                  ATSimplePermissionsRelationOrIndex(rel);
                  /* This command never recurses */
                  /* No command-specific prep needed */
                  pass = AT_PASS_MISC;
                  break;
            case AT_EnableTrig:           /* ENABLE TRIGGER variants */
            case AT_EnableAlwaysTrig:
            case AT_EnableReplicaTrig:
            case AT_EnableTrigAll:
            case AT_EnableTrigUser:
            case AT_DisableTrig:    /* DISABLE TRIGGER variants */
            case AT_DisableTrigAll:
            case AT_DisableTrigUser:
            case AT_EnableRule:           /* ENABLE/DISABLE RULE variants */
            case AT_EnableAlwaysRule:
            case AT_EnableReplicaRule:
            case AT_DisableRule:
            case AT_AddInherit:           /* INHERIT / NO INHERIT */
            case AT_DropInherit:
                  ATSimplePermissions(rel, false);
                  /* These commands never recurse */
                  /* No command-specific prep needed */
                  pass = AT_PASS_MISC;
                  break;
            default:                      /* oops */
                  elog(ERROR, "unrecognized alter table type: %d",
                         (int) cmd->subtype);
                  pass = 0;               /* keep compiler quiet */
                  break;
      }

      /* Add the subcommand to the appropriate list for phase 2 */
      tab->subcmds[pass] = lappend(tab->subcmds[pass], cmd);
}

/*
 * ATRewriteCatalogs
 *
 * Traffic cop for ALTER TABLE Phase 2 operations.    Subcommands are
 * dispatched in a "safe" execution order (designed to avoid unnecessary
 * conflicts).
 */
static void
ATRewriteCatalogs(List **wqueue)
{
      int               pass;
      ListCell   *ltab;

      /*
       * We process all the tables "in parallel", one pass at a time.  This is
       * needed because we may have to propagate work from one table to another
       * (specifically, ALTER TYPE on a foreign key's PK has to dispatch the
       * re-adding of the foreign key constraint to the other table).  Work can
       * only be propagated into later passes, however.
       */
      for (pass = 0; pass < AT_NUM_PASSES; pass++)
      {
            /* Go through each table that needs to be processed */
            foreach(ltab, *wqueue)
            {
                  AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
                  List     *subcmds = tab->subcmds[pass];
                  Relation    rel;
                  ListCell   *lcmd;

                  if (subcmds == NIL)
                        continue;

                  /*
                   * Exclusive lock was obtained by phase 1, needn't get it again
                   */
                  rel = relation_open(tab->relid, NoLock);

                  foreach(lcmd, subcmds)
                        ATExecCmd(wqueue, tab, rel, (AlterTableCmd *) lfirst(lcmd));

                  /*
                   * After the ALTER TYPE pass, do cleanup work (this is not done in
                   * ATExecAlterColumnType since it should be done only once if
                   * multiple columns of a table are altered).
                   */
                  if (pass == AT_PASS_ALTER_TYPE)
                        ATPostAlterTypeCleanup(wqueue, tab);

                  relation_close(rel, NoLock);
            }
      }

      /*
       * Check to see if a toast table must be added, if we executed any
       * subcommands that might have added a column or changed column storage.
       */
      foreach(ltab, *wqueue)
      {
            AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);

            if (tab->relkind == RELKIND_RELATION &&
                  (tab->subcmds[AT_PASS_ADD_COL] ||
                   tab->subcmds[AT_PASS_ALTER_TYPE] ||
                   tab->subcmds[AT_PASS_COL_ATTRS]))
                  AlterTableCreateToastTable(tab->relid, InvalidOid,
                                                         (Datum) 0, false);
      }
}

/*
 * ATExecCmd: dispatch a subcommand to appropriate execution routine
 */
static void
ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
              AlterTableCmd *cmd)
{
      switch (cmd->subtype)
      {
            case AT_AddColumn:            /* ADD COLUMN */
            case AT_AddColumnToView:            /* add column via CREATE OR REPLACE
                                                             * VIEW */
                  ATExecAddColumn(tab, rel, (ColumnDef *) cmd->def, false);
                  break;
            case AT_ColumnDefault:  /* ALTER COLUMN DEFAULT */
                  ATExecColumnDefault(rel, cmd->name, cmd->def);
                  break;
            case AT_DropNotNull:    /* ALTER COLUMN DROP NOT NULL */
                  ATExecDropNotNull(rel, cmd->name);
                  break;
            case AT_SetNotNull:           /* ALTER COLUMN SET NOT NULL */
                  ATExecSetNotNull(tab, rel, cmd->name);
                  break;
            case AT_SetStatistics:  /* ALTER COLUMN STATISTICS */
                  ATExecSetStatistics(rel, cmd->name, cmd->def);
                  break;
            case AT_SetStorage:           /* ALTER COLUMN STORAGE */
                  ATExecSetStorage(rel, cmd->name, cmd->def);
                  break;
            case AT_DropColumn:           /* DROP COLUMN */
                  ATExecDropColumn(wqueue, rel, cmd->name,
                                           cmd->behavior, false, false);
                  break;
            case AT_DropColumnRecurse:          /* DROP COLUMN with recursion */
                  ATExecDropColumn(wqueue, rel, cmd->name,
                                           cmd->behavior, true, false);
                  break;
            case AT_AddIndex:       /* ADD INDEX */
                  ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, false);
                  break;
            case AT_ReAddIndex:           /* ADD INDEX */
                  ATExecAddIndex(tab, rel, (IndexStmt *) cmd->def, true);
                  break;
            case AT_AddConstraint:  /* ADD CONSTRAINT */
                  ATExecAddConstraint(wqueue, tab, rel, cmd->def, false);
                  break;
            case AT_AddConstraintRecurse: /* ADD CONSTRAINT with recursion */
                  ATExecAddConstraint(wqueue, tab, rel, cmd->def, true);
                  break;
            case AT_DropConstraint: /* DROP CONSTRAINT */
                  ATExecDropConstraint(rel, cmd->name, cmd->behavior, false, false);
                  break;
            case AT_DropConstraintRecurse:      /* DROP CONSTRAINT with recursion */
                  ATExecDropConstraint(rel, cmd->name, cmd->behavior, true, false);
                  break;
            case AT_AlterColumnType:            /* ALTER COLUMN TYPE */
                  ATExecAlterColumnType(tab, rel, cmd->name, (TypeName *) cmd->def);
                  break;
            case AT_ChangeOwner:    /* ALTER OWNER */
                  ATExecChangeOwner(RelationGetRelid(rel),
                                            get_roleid_checked(cmd->name),
                                            false);
                  break;
            case AT_ClusterOn:            /* CLUSTER ON */
                  ATExecClusterOn(rel, cmd->name);
                  break;
            case AT_DropCluster:    /* SET WITHOUT CLUSTER */
                  ATExecDropCluster(rel);
                  break;
            case AT_AddOids:        /* SET WITH OIDS */
                  /* Use the ADD COLUMN code, unless prep decided to do nothing */
                  if (cmd->def != NULL)
                        ATExecAddColumn(tab, rel, (ColumnDef *) cmd->def, true);
                  break;
            case AT_DropOids:       /* SET WITHOUT OIDS */

                  /*
                   * Nothing to do here; we'll have generated a DropColumn
                   * subcommand to do the real work
                   */
                  break;
            case AT_SetTableSpace:  /* SET TABLESPACE */

                  /*
                   * Nothing to do here; Phase 3 does the work
                   */
                  break;
            case AT_SetRelOptions:  /* SET (...) */
                  ATExecSetRelOptions(rel, (List *) cmd->def, false);
                  break;
            case AT_ResetRelOptions:            /* RESET (...) */
                  ATExecSetRelOptions(rel, (List *) cmd->def, true);
                  break;

            case AT_EnableTrig:           /* ENABLE TRIGGER name */
                  ATExecEnableDisableTrigger(rel, cmd->name,
                                                         TRIGGER_FIRES_ON_ORIGIN, false);
                  break;
            case AT_EnableAlwaysTrig:           /* ENABLE ALWAYS TRIGGER name */
                  ATExecEnableDisableTrigger(rel, cmd->name,
                                                         TRIGGER_FIRES_ALWAYS, false);
                  break;
            case AT_EnableReplicaTrig:          /* ENABLE REPLICA TRIGGER name */
                  ATExecEnableDisableTrigger(rel, cmd->name,
                                                         TRIGGER_FIRES_ON_REPLICA, false);
                  break;
            case AT_DisableTrig:    /* DISABLE TRIGGER name */
                  ATExecEnableDisableTrigger(rel, cmd->name,
                                                         TRIGGER_DISABLED, false);
                  break;
            case AT_EnableTrigAll:  /* ENABLE TRIGGER ALL */
                  ATExecEnableDisableTrigger(rel, NULL,
                                                         TRIGGER_FIRES_ON_ORIGIN, false);
                  break;
            case AT_DisableTrigAll: /* DISABLE TRIGGER ALL */
                  ATExecEnableDisableTrigger(rel, NULL,
                                                         TRIGGER_DISABLED, false);
                  break;
            case AT_EnableTrigUser: /* ENABLE TRIGGER USER */
                  ATExecEnableDisableTrigger(rel, NULL,
                                                         TRIGGER_FIRES_ON_ORIGIN, true);
                  break;
            case AT_DisableTrigUser:            /* DISABLE TRIGGER USER */
                  ATExecEnableDisableTrigger(rel, NULL,
                                                         TRIGGER_DISABLED, true);
                  break;

            case AT_EnableRule:           /* ENABLE RULE name */
                  ATExecEnableDisableRule(rel, cmd->name,
                                                      RULE_FIRES_ON_ORIGIN);
                  break;
            case AT_EnableAlwaysRule:           /* ENABLE ALWAYS RULE name */
                  ATExecEnableDisableRule(rel, cmd->name,
                                                      RULE_FIRES_ALWAYS);
                  break;
            case AT_EnableReplicaRule:          /* ENABLE REPLICA RULE name */
                  ATExecEnableDisableRule(rel, cmd->name,
                                                      RULE_FIRES_ON_REPLICA);
                  break;
            case AT_DisableRule:    /* DISABLE RULE name */
                  ATExecEnableDisableRule(rel, cmd->name,
                                                      RULE_DISABLED);
                  break;

            case AT_AddInherit:
                  ATExecAddInherit(rel, (RangeVar *) cmd->def);
                  break;
            case AT_DropInherit:
                  ATExecDropInherit(rel, (RangeVar *) cmd->def);
                  break;
            default:                      /* oops */
                  elog(ERROR, "unrecognized alter table type: %d",
                         (int) cmd->subtype);
                  break;
      }

      /*
       * Bump the command counter to ensure the next subcommand in the sequence
       * can see the changes so far
       */
      CommandCounterIncrement();
}

/*
 * ATRewriteTables: ALTER TABLE phase 3
 */
static void
ATRewriteTables(List **wqueue)
{
      ListCell   *ltab;

      /* Go through each table that needs to be checked or rewritten */
      foreach(ltab, *wqueue)
      {
            AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);

            /*
             * We only need to rewrite the table if at least one column needs to
             * be recomputed, or we are adding/removing the OID column.
             */
            if (tab->newvals != NIL || tab->new_changeoids)
            {
                  /* Build a temporary relation and copy data */
                  Oid               OIDNewHeap;
                  char        NewHeapName[NAMEDATALEN];
                  Oid               NewTableSpace;
                  Relation    OldHeap;
                  ObjectAddress object;

                  OldHeap = heap_open(tab->relid, NoLock);

                  /*
                   * We can never allow rewriting of shared or nailed-in-cache
                   * relations, because we can't support changing their relfilenode
                   * values.
                   */
                  if (OldHeap->rd_rel->relisshared || OldHeap->rd_isnailed)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("cannot rewrite system relation \"%s\"",
                                                RelationGetRelationName(OldHeap))));

                  /*
                   * Don't allow rewrite on temp tables of other backends ... their
                   * local buffer manager is not going to cope.
                   */
                  if (RELATION_IS_OTHER_TEMP(OldHeap))
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg("cannot rewrite temporary tables of other sessions")));

                  /*
                   * Select destination tablespace (same as original unless user
                   * requested a change)
                   */
                  if (tab->newTableSpace)
                        NewTableSpace = tab->newTableSpace;
                  else
                        NewTableSpace = OldHeap->rd_rel->reltablespace;

                  heap_close(OldHeap, NoLock);

                  /*
                   * Create the new heap, using a temporary name in the same
                   * namespace as the existing table.  NOTE: there is some risk of
                   * collision with user relnames.  Working around this seems more
                   * trouble than it's worth; in particular, we can't create the new
                   * heap in a different namespace from the old, or we will have
                   * problems with the TEMP status of temp tables.
                   */
                  snprintf(NewHeapName, sizeof(NewHeapName),
                               "pg_temp_%u", tab->relid);

                  OIDNewHeap = make_new_heap(tab->relid, NewHeapName, NewTableSpace);

                  /*
                   * Copy the heap data into the new table with the desired
                   * modifications, and test the current data within the table
                   * against new constraints generated by ALTER TABLE commands.
                   */
                  ATRewriteTable(tab, OIDNewHeap);

                  /*
                   * Swap the physical files of the old and new heaps.  Since we are
                   * generating a new heap, we can use RecentXmin for the table's
                   * new relfrozenxid because we rewrote all the tuples on
                   * ATRewriteTable, so no older Xid remains on the table.
                   */
                  swap_relation_files(tab->relid, OIDNewHeap, RecentXmin);

                  CommandCounterIncrement();

                  /* Destroy new heap with old filenode */
                  object.classId = RelationRelationId;
                  object.objectId = OIDNewHeap;
                  object.objectSubId = 0;

                  /*
                   * The new relation is local to our transaction and we know
                   * nothing depends on it, so DROP_RESTRICT should be OK.
                   */
                  performDeletion(&object, DROP_RESTRICT);
                  /* performDeletion does CommandCounterIncrement at end */

                  /*
                   * Rebuild each index on the relation (but not the toast table,
                   * which is all-new anyway).  We do not need
                   * CommandCounterIncrement() because reindex_relation does it.
                   */
                  reindex_relation(tab->relid, false);
            }
            else
            {
                  /*
                   * Test the current data within the table against new constraints
                   * generated by ALTER TABLE commands, but don't rebuild data.
                   */
                  if (tab->constraints != NIL || tab->new_notnull)
                        ATRewriteTable(tab, InvalidOid);

                  /*
                   * If we had SET TABLESPACE but no reason to reconstruct tuples,
                   * just do a block-by-block copy.
                   */
                  if (tab->newTableSpace)
                        ATExecSetTableSpace(tab->relid, tab->newTableSpace);
            }
      }

      /*
       * Foreign key constraints are checked in a final pass, since (a) it's
       * generally best to examine each one separately, and (b) it's at least
       * theoretically possible that we have changed both relations of the
       * foreign key, and we'd better have finished both rewrites before we try
       * to read the tables.
       */
      foreach(ltab, *wqueue)
      {
            AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
            Relation    rel = NULL;
            ListCell   *lcon;

            foreach(lcon, tab->constraints)
            {
                  NewConstraint *con = lfirst(lcon);

                  if (con->contype == CONSTR_FOREIGN)
                  {
                        FkConstraint *fkconstraint = (FkConstraint *) con->qual;
                        Relation    refrel;

                        if (rel == NULL)
                        {
                              /* Long since locked, no need for another */
                              rel = heap_open(tab->relid, NoLock);
                        }

                        refrel = heap_open(con->refrelid, RowShareLock);

                        validateForeignKeyConstraint(fkconstraint, rel, refrel,
                                                                   con->conid);

                        heap_close(refrel, NoLock);
                  }
            }

            if (rel)
                  heap_close(rel, NoLock);
      }
}

/*
 * ATRewriteTable: scan or rewrite one table
 *
 * OIDNewHeap is InvalidOid if we don't need to rewrite
 */
static void
ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap)
{
      Relation    oldrel;
      Relation    newrel;
      TupleDesc   oldTupDesc;
      TupleDesc   newTupDesc;
      bool        needscan = false;
      List     *notnull_attrs;
      int               i;
      ListCell   *l;
      EState         *estate;

      /*
       * Open the relation(s).  We have surely already locked the existing
       * table.
       */
      oldrel = heap_open(tab->relid, NoLock);
      oldTupDesc = tab->oldDesc;
      newTupDesc = RelationGetDescr(oldrel);          /* includes all mods */

      if (OidIsValid(OIDNewHeap))
            newrel = heap_open(OIDNewHeap, AccessExclusiveLock);
      else
            newrel = NULL;

      /*
       * If we need to rewrite the table, the operation has to be propagated to
       * tables that use this table's rowtype as a column type.
       *
       * (Eventually this will probably become true for scans as well, but at
       * the moment a composite type does not enforce any constraints, so it's
       * not necessary/appropriate to enforce them just during ALTER.)
       */
      if (newrel)
            find_composite_type_dependencies(oldrel->rd_rel->reltype,
                                                             RelationGetRelationName(oldrel),
                                                             NULL);

      /*
       * Generate the constraint and default execution states
       */

      estate = CreateExecutorState();

      /* Build the needed expression execution states */
      foreach(l, tab->constraints)
      {
            NewConstraint *con = lfirst(l);

            switch (con->contype)
            {
                  case CONSTR_CHECK:
                        needscan = true;
                        con->qualstate = (List *)
                              ExecPrepareExpr((Expr *) con->qual, estate);
                        break;
                  case CONSTR_FOREIGN:
                        /* Nothing to do here */
                        break;
                  default:
                        elog(ERROR, "unrecognized constraint type: %d",
                               (int) con->contype);
            }
      }

      foreach(l, tab->newvals)
      {
            NewColumnValue *ex = lfirst(l);

            ex->exprstate = ExecPrepareExpr((Expr *) ex->expr, estate);
      }

      notnull_attrs = NIL;
      if (newrel || tab->new_notnull)
      {
            /*
             * If we are rebuilding the tuples OR if we added any new NOT NULL
             * constraints, check all not-null constraints.  This is a bit of
             * overkill but it minimizes risk of bugs, and heap_attisnull is a
             * pretty cheap test anyway.
             */
            for (i = 0; i < newTupDesc->natts; i++)
            {
                  if (newTupDesc->attrs[i]->attnotnull &&
                        !newTupDesc->attrs[i]->attisdropped)
                        notnull_attrs = lappend_int(notnull_attrs, i);
            }
            if (notnull_attrs)
                  needscan = true;
      }

      if (newrel || needscan)
      {
            ExprContext *econtext;
            Datum    *values;
            bool     *isnull;
            TupleTableSlot *oldslot;
            TupleTableSlot *newslot;
            HeapScanDesc scan;
            HeapTuple   tuple;
            MemoryContext oldCxt;
            List     *dropped_attrs = NIL;
            ListCell   *lc;

            econtext = GetPerTupleExprContext(estate);

            /*
             * Make tuple slots for old and new tuples.  Note that even when the
             * tuples are the same, the tupDescs might not be (consider ADD COLUMN
             * without a default).
             */
            oldslot = MakeSingleTupleTableSlot(oldTupDesc);
            newslot = MakeSingleTupleTableSlot(newTupDesc);

            /* Preallocate values/isnull arrays */
            i = Max(newTupDesc->natts, oldTupDesc->natts);
            values = (Datum *) palloc(i * sizeof(Datum));
            isnull = (bool *) palloc(i * sizeof(bool));
            memset(values, 0, i * sizeof(Datum));
            memset(isnull, true, i * sizeof(bool));

            /*
             * Any attributes that are dropped according to the new tuple
             * descriptor can be set to NULL. We precompute the list of dropped
             * attributes to avoid needing to do so in the per-tuple loop.
             */
            for (i = 0; i < newTupDesc->natts; i++)
            {
                  if (newTupDesc->attrs[i]->attisdropped)
                        dropped_attrs = lappend_int(dropped_attrs, i);
            }

            /*
             * Scan through the rows, generating a new row if needed and then
             * checking all the constraints.
             */
            scan = heap_beginscan(oldrel, SnapshotNow, 0, NULL);

            /*
             * Switch to per-tuple memory context and reset it for each tuple
             * produced, so we don't leak memory.
             */
            oldCxt = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));

            while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
            {
                  if (newrel)
                  {
                        Oid               tupOid = InvalidOid;

                        /* Extract data from old tuple */
                        heap_deform_tuple(tuple, oldTupDesc, values, isnull);
                        if (oldTupDesc->tdhasoid)
                              tupOid = HeapTupleGetOid(tuple);

                        /* Set dropped attributes to null in new tuple */
                        foreach(lc, dropped_attrs)
                              isnull[lfirst_int(lc)] = true;

                        /*
                         * Process supplied expressions to replace selected columns.
                         * Expression inputs come from the old tuple.
                         */
                        ExecStoreTuple(tuple, oldslot, InvalidBuffer, false);
                        econtext->ecxt_scantuple = oldslot;

                        foreach(l, tab->newvals)
                        {
                              NewColumnValue *ex = lfirst(l);

                              values[ex->attnum - 1] = ExecEvalExpr(ex->exprstate,
                                                                                      econtext,
                                                                               &isnull[ex->attnum - 1],
                                                                                      NULL);
                        }

                        /*
                         * Form the new tuple. Note that we don't explicitly pfree it,
                         * since the per-tuple memory context will be reset shortly.
                         */
                        tuple = heap_form_tuple(newTupDesc, values, isnull);

                        /* Preserve OID, if any */
                        if (newTupDesc->tdhasoid)
                              HeapTupleSetOid(tuple, tupOid);
                  }

                  /* Now check any constraints on the possibly-changed tuple */
                  ExecStoreTuple(tuple, newslot, InvalidBuffer, false);
                  econtext->ecxt_scantuple = newslot;

                  foreach(l, notnull_attrs)
                  {
                        int               attn = lfirst_int(l);

                        if (heap_attisnull(tuple, attn + 1))
                              ereport(ERROR,
                                          (errcode(ERRCODE_NOT_NULL_VIOLATION),
                                           errmsg("column \"%s\" contains null values",
                                                NameStr(newTupDesc->attrs[attn]->attname))));
                  }

                  foreach(l, tab->constraints)
                  {
                        NewConstraint *con = lfirst(l);

                        switch (con->contype)
                        {
                              case CONSTR_CHECK:
                                    if (!ExecQual(con->qualstate, econtext, true))
                                          ereport(ERROR,
                                                      (errcode(ERRCODE_CHECK_VIOLATION),
                                                       errmsg("check constraint \"%s\" is violated by some row",
                                                                  con->name)));
                                    break;
                              case CONSTR_FOREIGN:
                                    /* Nothing to do here */
                                    break;
                              default:
                                    elog(ERROR, "unrecognized constraint type: %d",
                                           (int) con->contype);
                        }
                  }

                  /* Write the tuple out to the new relation */
                  if (newrel)
                        simple_heap_insert(newrel, tuple);

                  ResetExprContext(econtext);

                  CHECK_FOR_INTERRUPTS();
            }

            MemoryContextSwitchTo(oldCxt);
            heap_endscan(scan);

            ExecDropSingleTupleTableSlot(oldslot);
            ExecDropSingleTupleTableSlot(newslot);
      }

      FreeExecutorState(estate);

      heap_close(oldrel, NoLock);
      if (newrel)
            heap_close(newrel, NoLock);
}

/*
 * ATGetQueueEntry: find or create an entry in the ALTER TABLE work queue
 */
static AlteredTableInfo *
ATGetQueueEntry(List **wqueue, Relation rel)
{
      Oid               relid = RelationGetRelid(rel);
      AlteredTableInfo *tab;
      ListCell   *ltab;

      foreach(ltab, *wqueue)
      {
            tab = (AlteredTableInfo *) lfirst(ltab);
            if (tab->relid == relid)
                  return tab;
      }

      /*
       * Not there, so add it.  Note that we make a copy of the relation's
       * existing descriptor before anything interesting can happen to it.
       */
      tab = (AlteredTableInfo *) palloc0(sizeof(AlteredTableInfo));
      tab->relid = relid;
      tab->relkind = rel->rd_rel->relkind;
      tab->oldDesc = CreateTupleDescCopy(RelationGetDescr(rel));

      *wqueue = lappend(*wqueue, tab);

      return tab;
}

/*
 * ATSimplePermissions
 *
 * - Ensure that it is a relation (or possibly a view)
 * - Ensure this user is the owner
 * - Ensure that it is not a system table
 */
static void
ATSimplePermissions(Relation rel, bool allowView)
{
      if (rel->rd_rel->relkind != RELKIND_RELATION)
      {
            if (allowView)
            {
                  if (rel->rd_rel->relkind != RELKIND_VIEW)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not a table or view",
                                                RelationGetRelationName(rel))));
            }
            else
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is not a table",
                                          RelationGetRelationName(rel))));
      }

      /* Permissions checks */
      if (!pg_class_ownercheck(RelationGetRelid(rel), GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 RelationGetRelationName(rel));

      if (!allowSystemTableMods && IsSystemRelation(rel))
            ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                         errmsg("permission denied: \"%s\" is a system catalog",
                                    RelationGetRelationName(rel))));
}

/*
 * ATSimplePermissionsRelationOrIndex
 *
 * - Ensure that it is a relation or an index
 * - Ensure this user is the owner
 * - Ensure that it is not a system table
 */
static void
ATSimplePermissionsRelationOrIndex(Relation rel)
{
      if (rel->rd_rel->relkind != RELKIND_RELATION &&
            rel->rd_rel->relkind != RELKIND_INDEX)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a table or index",
                                    RelationGetRelationName(rel))));

      /* Permissions checks */
      if (!pg_class_ownercheck(RelationGetRelid(rel), GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 RelationGetRelationName(rel));

      if (!allowSystemTableMods && IsSystemRelation(rel))
            ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                         errmsg("permission denied: \"%s\" is a system catalog",
                                    RelationGetRelationName(rel))));
}

/*
 * ATSimpleRecursion
 *
 * Simple table recursion sufficient for most ALTER TABLE operations.
 * All direct and indirect children are processed in an unspecified order.
 * Note that if a child inherits from the original table via multiple
 * inheritance paths, it will be visited just once.
 */
static void
ATSimpleRecursion(List **wqueue, Relation rel,
                          AlterTableCmd *cmd, bool recurse)
{
      /*
       * Propagate to children if desired.  Non-table relations never have
       * children, so no need to search in that case.
       */
      if (recurse && rel->rd_rel->relkind == RELKIND_RELATION)
      {
            Oid               relid = RelationGetRelid(rel);
            ListCell   *child;
            List     *children;

            children = find_all_inheritors(relid, AccessExclusiveLock);

            /*
             * find_all_inheritors does the recursive search of the inheritance
             * hierarchy, so all we have to do is process all of the relids in the
             * list that it returns.
             */
            foreach(child, children)
            {
                  Oid               childrelid = lfirst_oid(child);
                  Relation    childrel;

                  if (childrelid == relid)
                        continue;
                  /* find_all_inheritors already got lock */
                  childrel = relation_open(childrelid, NoLock);
                  CheckTableNotInUse(childrel, "ALTER TABLE");
                  ATPrepCmd(wqueue, childrel, cmd, false, true);
                  relation_close(childrel, NoLock);
            }
      }
}

/*
 * ATOneLevelRecursion
 *
 * Here, we visit only direct inheritance children.  It is expected that
 * the command's prep routine will recurse again to find indirect children.
 * When using this technique, a multiply-inheriting child will be visited
 * multiple times.
 */
static void
ATOneLevelRecursion(List **wqueue, Relation rel,
                              AlterTableCmd *cmd)
{
      Oid               relid = RelationGetRelid(rel);
      ListCell   *child;
      List     *children;

      children = find_inheritance_children(relid, AccessExclusiveLock);

      foreach(child, children)
      {
            Oid               childrelid = lfirst_oid(child);
            Relation    childrel;

            /* find_inheritance_children already got lock */
            childrel = relation_open(childrelid, NoLock);
            CheckTableNotInUse(childrel, "ALTER TABLE");
            ATPrepCmd(wqueue, childrel, cmd, true, true);
            relation_close(childrel, NoLock);
      }
}


/*
 * find_composite_type_dependencies
 *
 * Check to see if a composite type is being used as a column in some
 * other table (possibly nested several levels deep in composite types!).
 * Eventually, we'd like to propagate the check or rewrite operation
 * into other such tables, but for now, just error out if we find any.
 *
 * Caller should provide either a table name or a type name (not both) to
 * report in the error message, if any.
 *
 * We assume that functions and views depending on the type are not reasons
 * to reject the ALTER.  (How safe is this really?)
 */
void
find_composite_type_dependencies(Oid typeOid,
                                                 const char *origTblName,
                                                 const char *origTypeName)
{
      Relation    depRel;
      ScanKeyData key[2];
      SysScanDesc depScan;
      HeapTuple   depTup;
      Oid               arrayOid;

      /*
       * We scan pg_depend to find those things that depend on the rowtype. (We
       * assume we can ignore refobjsubid for a rowtype.)
       */
      depRel = heap_open(DependRelationId, AccessShareLock);

      ScanKeyInit(&key[0],
                        Anum_pg_depend_refclassid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(TypeRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_refobjid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(typeOid));

      depScan = systable_beginscan(depRel, DependReferenceIndexId, true,
                                                 SnapshotNow, 2, key);

      while (HeapTupleIsValid(depTup = systable_getnext(depScan)))
      {
            Form_pg_depend pg_depend = (Form_pg_depend) GETSTRUCT(depTup);
            Relation    rel;
            Form_pg_attribute att;

            /* Ignore dependees that aren't user columns of relations */
            /* (we assume system columns are never of rowtypes) */
            if (pg_depend->classid != RelationRelationId ||
                  pg_depend->objsubid <= 0)
                  continue;

            rel = relation_open(pg_depend->objid, AccessShareLock);
            att = rel->rd_att->attrs[pg_depend->objsubid - 1];

            if (rel->rd_rel->relkind == RELKIND_RELATION)
            {
                  if (origTblName)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("cannot alter table \"%s\" because column \"%s\".\"%s\" uses its rowtype",
                                                origTblName,
                                                RelationGetRelationName(rel),
                                                NameStr(att->attname))));
                  else
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("cannot alter type \"%s\" because column \"%s\".\"%s\" uses it",
                                                origTypeName,
                                                RelationGetRelationName(rel),
                                                NameStr(att->attname))));
            }
            else if (OidIsValid(rel->rd_rel->reltype))
            {
                  /*
                   * A view or composite type itself isn't a problem, but we must
                   * recursively check for indirect dependencies via its rowtype.
                   */
                  find_composite_type_dependencies(rel->rd_rel->reltype,
                                                                   origTblName, origTypeName);
            }

            relation_close(rel, AccessShareLock);
      }

      systable_endscan(depScan);

      relation_close(depRel, AccessShareLock);

      /*
       * If there's an array type for the rowtype, must check for uses of it,
       * too.
       */
      arrayOid = get_array_type(typeOid);
      if (OidIsValid(arrayOid))
            find_composite_type_dependencies(arrayOid, origTblName, origTypeName);
}


/*
 * ALTER TABLE ADD COLUMN
 *
 * Adds an additional attribute to a relation making the assumption that
 * CHECK, NOT NULL, and FOREIGN KEY constraints will be removed from the
 * AT_AddColumn AlterTableCmd by parse_utilcmd.c and added as independent
 * AlterTableCmd's.
 */
static void
ATPrepAddColumn(List **wqueue, Relation rel, bool recurse,
                        AlterTableCmd *cmd)
{
      /*
       * Recurse to add the column to child classes, if requested.
       *
       * We must recurse one level at a time, so that multiply-inheriting
       * children are visited the right number of times and end up with the
       * right attinhcount.
       */
      if (recurse)
      {
            AlterTableCmd *childCmd = copyObject(cmd);
            ColumnDef  *colDefChild = (ColumnDef *) childCmd->def;

            /* Child should see column as singly inherited */
            colDefChild->inhcount = 1;
            colDefChild->is_local = false;

            ATOneLevelRecursion(wqueue, rel, childCmd);
      }
      else
      {
            /*
             * If we are told not to recurse, there had better not be any child
             * tables; else the addition would put them out of step.
             */
            if (find_inheritance_children(RelationGetRelid(rel), NoLock) != NIL)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("column must be added to child tables too")));
      }
}

static void
ATExecAddColumn(AlteredTableInfo *tab, Relation rel,
                        ColumnDef *colDef, bool isOid)
{
      Oid               myrelid = RelationGetRelid(rel);
      Relation    pgclass,
                        attrdesc;
      HeapTuple   reltup;
      FormData_pg_attribute attribute;
      int               newattnum;
      char        relkind;
      HeapTuple   typeTuple;
      Oid               typeOid;
      int32       typmod;
      Form_pg_type tform;
      Expr     *defval;

      attrdesc = heap_open(AttributeRelationId, RowExclusiveLock);

      /*
       * Are we adding the column to a recursion child?  If so, check whether to
       * merge with an existing definition for the column.
       */
      if (colDef->inhcount > 0)
      {
            HeapTuple   tuple;

            /* Does child already have a column by this name? */
            tuple = SearchSysCacheCopyAttName(myrelid, colDef->colname);
            if (HeapTupleIsValid(tuple))
            {
                  Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);
                  Oid               ctypeId;
                  int32       ctypmod;

                  /* Child column must match by type */
                  ctypeId = typenameTypeId(NULL, colDef->typename, &ctypmod);
                  if (ctypeId != childatt->atttypid ||
                        ctypmod != childatt->atttypmod)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                                     errmsg("child table \"%s\" has different type for column \"%s\"",
                                          RelationGetRelationName(rel), colDef->colname)));

                  /* If it's OID, child column must actually be OID */
                  if (isOid && childatt->attnum != ObjectIdAttributeNumber)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("child table \"%s\" has a conflicting \"%s\" column",
                                    RelationGetRelationName(rel), colDef->colname)));

                  /* Bump the existing child att's inhcount */
                  childatt->attinhcount++;
                  simple_heap_update(attrdesc, &tuple->t_self, tuple);
                  CatalogUpdateIndexes(attrdesc, tuple);

                  heap_freetuple(tuple);

                  /* Inform the user about the merge */
                  ereport(NOTICE,
                    (errmsg("merging definition of column \"%s\" for child \"%s\"",
                                colDef->colname, RelationGetRelationName(rel))));

                  heap_close(attrdesc, RowExclusiveLock);
                  return;
            }
      }

      pgclass = heap_open(RelationRelationId, RowExclusiveLock);

      reltup = SearchSysCacheCopy(RELOID,
                                                ObjectIdGetDatum(myrelid),
                                                0, 0, 0);
      if (!HeapTupleIsValid(reltup))
            elog(ERROR, "cache lookup failed for relation %u", myrelid);
      relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;

      /*
       * this test is deliberately not attisdropped-aware, since if one tries to
       * add a column matching a dropped column name, it's gonna fail anyway.
       */
      if (SearchSysCacheExists(ATTNAME,
                                           ObjectIdGetDatum(myrelid),
                                           PointerGetDatum(colDef->colname),
                                           0, 0))
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" already exists",
                                    colDef->colname, RelationGetRelationName(rel))));

      /* Determine the new attribute's number */
      if (isOid)
            newattnum = ObjectIdAttributeNumber;
      else
      {
            newattnum = ((Form_pg_class) GETSTRUCT(reltup))->relnatts + 1;
            if (newattnum > MaxHeapAttributeNumber)
                  ereport(ERROR,
                              (errcode(ERRCODE_TOO_MANY_COLUMNS),
                               errmsg("tables can have at most %d columns",
                                          MaxHeapAttributeNumber)));
      }

      typeTuple = typenameType(NULL, colDef->typename, &typmod);
      tform = (Form_pg_type) GETSTRUCT(typeTuple);
      typeOid = HeapTupleGetOid(typeTuple);

      /* make sure datatype is legal for a column */
      CheckAttributeType(colDef->colname, typeOid);

      /* construct new attribute's pg_attribute entry */
      attribute.attrelid = myrelid;
      namestrcpy(&(attribute.attname), colDef->colname);
      attribute.atttypid = typeOid;
      attribute.attstattarget = (newattnum > 0) ? -1 : 0;
      attribute.attlen = tform->typlen;
      attribute.attcacheoff = -1;
      attribute.atttypmod = typmod;
      attribute.attnum = newattnum;
      attribute.attbyval = tform->typbyval;
      attribute.attndims = list_length(colDef->typename->arrayBounds);
      attribute.attstorage = tform->typstorage;
      attribute.attalign = tform->typalign;
      attribute.attnotnull = colDef->is_not_null;
      attribute.atthasdef = false;
      attribute.attisdropped = false;
      attribute.attislocal = colDef->is_local;
      attribute.attinhcount = colDef->inhcount;
      /* attribute.attacl is handled by InsertPgAttributeTuple */

      ReleaseSysCache(typeTuple);

      InsertPgAttributeTuple(attrdesc, &attribute, NULL);

      heap_close(attrdesc, RowExclusiveLock);

      /*
       * Update pg_class tuple as appropriate
       */
      if (isOid)
            ((Form_pg_class) GETSTRUCT(reltup))->relhasoids = true;
      else
            ((Form_pg_class) GETSTRUCT(reltup))->relnatts = newattnum;

      simple_heap_update(pgclass, &reltup->t_self, reltup);

      /* keep catalog indexes current */
      CatalogUpdateIndexes(pgclass, reltup);

      heap_freetuple(reltup);

      heap_close(pgclass, RowExclusiveLock);

      /* Make the attribute's catalog entry visible */
      CommandCounterIncrement();

      /*
       * Store the DEFAULT, if any, in the catalogs
       */
      if (colDef->raw_default)
      {
            RawColumnDefault *rawEnt;

            rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
            rawEnt->attnum = attribute.attnum;
            rawEnt->raw_default = copyObject(colDef->raw_default);

            /*
             * This function is intended for CREATE TABLE, so it processes a
             * _list_ of defaults, but we just do one.
             */
            AddRelationNewConstraints(rel, list_make1(rawEnt), NIL, false, true);

            /* Make the additional catalog changes visible */
            CommandCounterIncrement();
      }

      /*
       * Tell Phase 3 to fill in the default expression, if there is one.
       *
       * If there is no default, Phase 3 doesn't have to do anything, because
       * that effectively means that the default is NULL.  The heap tuple access
       * routines always check for attnum > # of attributes in tuple, and return
       * NULL if so, so without any modification of the tuple data we will get
       * the effect of NULL values in the new column.
       *
       * An exception occurs when the new column is of a domain type: the domain
       * might have a NOT NULL constraint, or a check constraint that indirectly
       * rejects nulls.  If there are any domain constraints then we construct
       * an explicit NULL default value that will be passed through
       * CoerceToDomain processing.  (This is a tad inefficient, since it causes
       * rewriting the table which we really don't have to do, but the present
       * design of domain processing doesn't offer any simple way of checking
       * the constraints more directly.)
       *
       * Note: we use build_column_default, and not just the cooked default
       * returned by AddRelationNewConstraints, so that the right thing happens
       * when a datatype's default applies.
       *
       * We skip this step completely for views.      For a view, we can only get
       * here from CREATE OR REPLACE VIEW, which historically doesn't set up
       * defaults, not even for domain-typed columns.  And in any case we
       * mustn't invoke Phase 3 on a view, since it has no storage.
       */
      if (relkind != RELKIND_VIEW && attribute.attnum > 0)
      {
            defval = (Expr *) build_column_default(rel, attribute.attnum);

            if (!defval && GetDomainConstraints(typeOid) != NIL)
            {
                  Oid               baseTypeId;
                  int32       baseTypeMod;

                  baseTypeMod = typmod;
                  baseTypeId = getBaseTypeAndTypmod(typeOid, &baseTypeMod);
                  defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod);
                  defval = (Expr *) coerce_to_target_type(NULL,
                                                                              (Node *) defval,
                                                                              baseTypeId,
                                                                              typeOid,
                                                                              typmod,
                                                                              COERCION_ASSIGNMENT,
                                                                              COERCE_IMPLICIT_CAST,
                                                                              -1);
                  if (defval == NULL) /* should not happen */
                        elog(ERROR, "failed to coerce base type to domain");
            }

            if (defval)
            {
                  NewColumnValue *newval;

                  newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
                  newval->attnum = attribute.attnum;
                  newval->expr = defval;

                  tab->newvals = lappend(tab->newvals, newval);
            }

            /*
             * If the new column is NOT NULL, tell Phase 3 it needs to test that.
             * (Note we don't do this for an OID column.  OID will be marked not
             * null, but since it's filled specially, there's no need to test
             * anything.)
             */
            tab->new_notnull |= colDef->is_not_null;
      }

      /*
       * If we are adding an OID column, we have to tell Phase 3 to rewrite the
       * table to fix that.
       */
      if (isOid)
            tab->new_changeoids = true;

      /*
       * Add needed dependency entries for the new column.
       */
      add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
}

/*
 * Install a column's dependency on its datatype.
 */
static void
add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid)
{
      ObjectAddress myself,
                        referenced;

      myself.classId = RelationRelationId;
      myself.objectId = relid;
      myself.objectSubId = attnum;
      referenced.classId = TypeRelationId;
      referenced.objectId = typid;
      referenced.objectSubId = 0;
      recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
}

/*
 * ALTER TABLE SET WITH OIDS
 *
 * Basically this is an ADD COLUMN for the special OID column.    We have
 * to cons up a ColumnDef node because the ADD COLUMN code needs one.
 */
static void
ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd)
{
      /* If we're recursing to a child table, the ColumnDef is already set up */
      if (cmd->def == NULL)
      {
            ColumnDef  *cdef = makeNode(ColumnDef);

            cdef->colname = pstrdup("oid");
            cdef->typename = makeTypeNameFromOid(OIDOID, -1);
            cdef->inhcount = 0;
            cdef->is_local = true;
            cdef->is_not_null = true;
            cmd->def = (Node *) cdef;
      }
      ATPrepAddColumn(wqueue, rel, recurse, cmd);
}

/*
 * ALTER TABLE ALTER COLUMN DROP NOT NULL
 */
static void
ATExecDropNotNull(Relation rel, const char *colName)
{
      HeapTuple   tuple;
      AttrNumber  attnum;
      Relation    attr_rel;
      List     *indexoidlist;
      ListCell   *indexoidscan;

      /*
       * lookup the attribute
       */
      attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);

      tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);

      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));

      attnum = ((Form_pg_attribute) GETSTRUCT(tuple))->attnum;

      /* Prevent them from altering a system attribute */
      if (attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      /*
       * Check that the attribute is not in a primary key
       */

      /* Loop over all indexes on the relation */
      indexoidlist = RelationGetIndexList(rel);

      foreach(indexoidscan, indexoidlist)
      {
            Oid               indexoid = lfirst_oid(indexoidscan);
            HeapTuple   indexTuple;
            Form_pg_index indexStruct;
            int               i;

            indexTuple = SearchSysCache(INDEXRELID,
                                                      ObjectIdGetDatum(indexoid),
                                                      0, 0, 0);
            if (!HeapTupleIsValid(indexTuple))
                  elog(ERROR, "cache lookup failed for index %u", indexoid);
            indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);

            /* If the index is not a primary key, skip the check */
            if (indexStruct->indisprimary)
            {
                  /*
                   * Loop over each attribute in the primary key and see if it
                   * matches the to-be-altered attribute
                   */
                  for (i = 0; i < indexStruct->indnatts; i++)
                  {
                        if (indexStruct->indkey.values[i] == attnum)
                              ereport(ERROR,
                                          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                           errmsg("column \"%s\" is in a primary key",
                                                      colName)));
                  }
            }

            ReleaseSysCache(indexTuple);
      }

      list_free(indexoidlist);

      /*
       * Okay, actually perform the catalog change ... if needed
       */
      if (((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull)
      {
            ((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull = FALSE;

            simple_heap_update(attr_rel, &tuple->t_self, tuple);

            /* keep the system catalog indexes current */
            CatalogUpdateIndexes(attr_rel, tuple);
      }

      heap_close(attr_rel, RowExclusiveLock);
}

/*
 * ALTER TABLE ALTER COLUMN SET NOT NULL
 */
static void
ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
                         const char *colName)
{
      HeapTuple   tuple;
      AttrNumber  attnum;
      Relation    attr_rel;

      /*
       * lookup the attribute
       */
      attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);

      tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);

      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));

      attnum = ((Form_pg_attribute) GETSTRUCT(tuple))->attnum;

      /* Prevent them from altering a system attribute */
      if (attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      /*
       * Okay, actually perform the catalog change ... if needed
       */
      if (!((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull)
      {
            ((Form_pg_attribute) GETSTRUCT(tuple))->attnotnull = TRUE;

            simple_heap_update(attr_rel, &tuple->t_self, tuple);

            /* keep the system catalog indexes current */
            CatalogUpdateIndexes(attr_rel, tuple);

            /* Tell Phase 3 it needs to test the constraint */
            tab->new_notnull = true;
      }

      heap_close(attr_rel, RowExclusiveLock);
}

/*
 * ALTER TABLE ALTER COLUMN SET/DROP DEFAULT
 */
static void
ATExecColumnDefault(Relation rel, const char *colName,
                              Node *newDefault)
{
      AttrNumber  attnum;

      /*
       * get the number of the attribute
       */
      attnum = get_attnum(RelationGetRelid(rel), colName);
      if (attnum == InvalidAttrNumber)
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));

      /* Prevent them from altering a system attribute */
      if (attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      /*
       * Remove any old default for the column.  We use RESTRICT here for
       * safety, but at present we do not expect anything to depend on the
       * default.
       */
      RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false);

      if (newDefault)
      {
            /* SET DEFAULT */
            RawColumnDefault *rawEnt;

            rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
            rawEnt->attnum = attnum;
            rawEnt->raw_default = newDefault;

            /*
             * This function is intended for CREATE TABLE, so it processes a
             * _list_ of defaults, but we just do one.
             */
            AddRelationNewConstraints(rel, list_make1(rawEnt), NIL, false, true);
      }
}

/*
 * ALTER TABLE ALTER COLUMN SET STATISTICS
 */
static void
ATPrepSetStatistics(Relation rel, const char *colName, Node *flagValue)
{
      /*
       * We do our own permission checking because (a) we want to allow SET
       * STATISTICS on indexes (for expressional index columns), and (b) we want
       * to allow SET STATISTICS on system catalogs without requiring
       * allowSystemTableMods to be turned on.
       */
      if (rel->rd_rel->relkind != RELKIND_RELATION &&
            rel->rd_rel->relkind != RELKIND_INDEX)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a table or index",
                                    RelationGetRelationName(rel))));

      /* Permissions checks */
      if (!pg_class_ownercheck(RelationGetRelid(rel), GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 RelationGetRelationName(rel));
}

static void
ATExecSetStatistics(Relation rel, const char *colName, Node *newValue)
{
      int               newtarget;
      Relation    attrelation;
      HeapTuple   tuple;
      Form_pg_attribute attrtuple;

      Assert(IsA(newValue, Integer));
      newtarget = intVal(newValue);

      /*
       * Limit target to a sane range
       */
      if (newtarget < -1)
      {
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("statistics target %d is too low",
                                    newtarget)));
      }
      else if (newtarget > 10000)
      {
            newtarget = 10000;
            ereport(WARNING,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("lowering statistics target to %d",
                                    newtarget)));
      }

      attrelation = heap_open(AttributeRelationId, RowExclusiveLock);

      tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);

      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));
      attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);

      if (attrtuple->attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      attrtuple->attstattarget = newtarget;

      simple_heap_update(attrelation, &tuple->t_self, tuple);

      /* keep system catalog indexes current */
      CatalogUpdateIndexes(attrelation, tuple);

      heap_freetuple(tuple);

      heap_close(attrelation, RowExclusiveLock);
}

/*
 * ALTER TABLE ALTER COLUMN SET STORAGE
 */
static void
ATExecSetStorage(Relation rel, const char *colName, Node *newValue)
{
      char     *storagemode;
      char        newstorage;
      Relation    attrelation;
      HeapTuple   tuple;
      Form_pg_attribute attrtuple;

      Assert(IsA(newValue, String));
      storagemode = strVal(newValue);

      if (pg_strcasecmp(storagemode, "plain") == 0)
            newstorage = 'p';
      else if (pg_strcasecmp(storagemode, "external") == 0)
            newstorage = 'e';
      else if (pg_strcasecmp(storagemode, "extended") == 0)
            newstorage = 'x';
      else if (pg_strcasecmp(storagemode, "main") == 0)
            newstorage = 'm';
      else
      {
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("invalid storage type \"%s\"",
                                    storagemode)));
            newstorage = 0;               /* keep compiler quiet */
      }

      attrelation = heap_open(AttributeRelationId, RowExclusiveLock);

      tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);

      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));
      attrtuple = (Form_pg_attribute) GETSTRUCT(tuple);

      if (attrtuple->attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      /*
       * safety check: do not allow toasted storage modes unless column datatype
       * is TOAST-aware.
       */
      if (newstorage == 'p' || TypeIsToastable(attrtuple->atttypid))
            attrtuple->attstorage = newstorage;
      else
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("column data type %s can only have storage PLAIN",
                                    format_type_be(attrtuple->atttypid))));

      simple_heap_update(attrelation, &tuple->t_self, tuple);

      /* keep system catalog indexes current */
      CatalogUpdateIndexes(attrelation, tuple);

      heap_freetuple(tuple);

      heap_close(attrelation, RowExclusiveLock);
}


/*
 * ALTER TABLE DROP COLUMN
 *
 * DROP COLUMN cannot use the normal ALTER TABLE recursion mechanism,
 * because we have to decide at runtime whether to recurse or not depending
 * on whether attinhcount goes to zero or not.  (We can't check this in a
 * static pre-pass because it won't handle multiple inheritance situations
 * correctly.)
 */
static void
ATExecDropColumn(List **wqueue, Relation rel, const char *colName,
                         DropBehavior behavior,
                         bool recurse, bool recursing)
{
      HeapTuple   tuple;
      Form_pg_attribute targetatt;
      AttrNumber  attnum;
      List     *children;
      ObjectAddress object;

      /* At top level, permission check was done in ATPrepCmd, else do it */
      if (recursing)
            ATSimplePermissions(rel, false);

      /*
       * get the number of the attribute
       */
      tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));
      targetatt = (Form_pg_attribute) GETSTRUCT(tuple);

      attnum = targetatt->attnum;

      /* Can't drop a system attribute, except OID */
      if (attnum <= 0 && attnum != ObjectIdAttributeNumber)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot drop system column \"%s\"",
                                    colName)));

      /* Don't drop inherited columns */
      if (targetatt->attinhcount > 0 && !recursing)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("cannot drop inherited column \"%s\"",
                                    colName)));

      ReleaseSysCache(tuple);

      /*
       * Propagate to children as appropriate.  Unlike most other ALTER
       * routines, we have to do this one level of recursion at a time; we can't
       * use find_all_inheritors to do it in one pass.
       */
      children = find_inheritance_children(RelationGetRelid(rel),
                                                             AccessExclusiveLock);

      if (children)
      {
            Relation    attr_rel;
            ListCell   *child;

            attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);
            foreach(child, children)
            {
                  Oid               childrelid = lfirst_oid(child);
                  Relation    childrel;
                  Form_pg_attribute childatt;

                  /* find_inheritance_children already got lock */
                  childrel = heap_open(childrelid, NoLock);
                  CheckTableNotInUse(childrel, "ALTER TABLE");

                  tuple = SearchSysCacheCopyAttName(childrelid, colName);
                  if (!HeapTupleIsValid(tuple))       /* shouldn't happen */
                        elog(ERROR, "cache lookup failed for attribute \"%s\" of relation %u",
                               colName, childrelid);
                  childatt = (Form_pg_attribute) GETSTRUCT(tuple);

                  if (childatt->attinhcount <= 0)           /* shouldn't happen */
                        elog(ERROR, "relation %u has non-inherited attribute \"%s\"",
                               childrelid, colName);

                  if (recurse)
                  {
                        /*
                         * If the child column has other definition sources, just
                         * decrement its inheritance count; if not, recurse to delete
                         * it.
                         */
                        if (childatt->attinhcount == 1 && !childatt->attislocal)
                        {
                              /* Time to delete this child column, too */
                              ATExecDropColumn(wqueue, childrel, colName,
                                                       behavior, true, true);
                        }
                        else
                        {
                              /* Child column must survive my deletion */
                              childatt->attinhcount--;

                              simple_heap_update(attr_rel, &tuple->t_self, tuple);

                              /* keep the system catalog indexes current */
                              CatalogUpdateIndexes(attr_rel, tuple);

                              /* Make update visible */
                              CommandCounterIncrement();
                        }
                  }
                  else
                  {
                        /*
                         * If we were told to drop ONLY in this table (no recursion),
                         * we need to mark the inheritors' attributes as locally
                         * defined rather than inherited.
                         */
                        childatt->attinhcount--;
                        childatt->attislocal = true;

                        simple_heap_update(attr_rel, &tuple->t_self, tuple);

                        /* keep the system catalog indexes current */
                        CatalogUpdateIndexes(attr_rel, tuple);

                        /* Make update visible */
                        CommandCounterIncrement();
                  }

                  heap_freetuple(tuple);

                  heap_close(childrel, NoLock);
            }
            heap_close(attr_rel, RowExclusiveLock);
      }

      /*
       * Perform the actual column deletion
       */
      object.classId = RelationRelationId;
      object.objectId = RelationGetRelid(rel);
      object.objectSubId = attnum;

      performDeletion(&object, behavior);

      /*
       * If we dropped the OID column, must adjust pg_class.relhasoids and tell
       * Phase 3 to physically get rid of the column.
       */
      if (attnum == ObjectIdAttributeNumber)
      {
            Relation    class_rel;
            Form_pg_class tuple_class;
            AlteredTableInfo *tab;

            class_rel = heap_open(RelationRelationId, RowExclusiveLock);

            tuple = SearchSysCacheCopy(RELOID,
                                                   ObjectIdGetDatum(RelationGetRelid(rel)),
                                                   0, 0, 0);
            if (!HeapTupleIsValid(tuple))
                  elog(ERROR, "cache lookup failed for relation %u",
                         RelationGetRelid(rel));
            tuple_class = (Form_pg_class) GETSTRUCT(tuple);

            tuple_class->relhasoids = false;
            simple_heap_update(class_rel, &tuple->t_self, tuple);

            /* Keep the catalog indexes up to date */
            CatalogUpdateIndexes(class_rel, tuple);

            heap_close(class_rel, RowExclusiveLock);

            /* Find or create work queue entry for this table */
            tab = ATGetQueueEntry(wqueue, rel);

            /* Tell Phase 3 to physically remove the OID column */
            tab->new_changeoids = true;
      }
}

/*
 * ALTER TABLE ADD INDEX
 *
 * There is no such command in the grammar, but parse_utilcmd.c converts
 * UNIQUE and PRIMARY KEY constraints into AT_AddIndex subcommands.  This lets
 * us schedule creation of the index at the appropriate time during ALTER.
 */
static void
ATExecAddIndex(AlteredTableInfo *tab, Relation rel,
                     IndexStmt *stmt, bool is_rebuild)
{
      bool        check_rights;
      bool        skip_build;
      bool        quiet;

      Assert(IsA(stmt, IndexStmt));

      /* suppress schema rights check when rebuilding existing index */
      check_rights = !is_rebuild;
      /* skip index build if phase 3 will have to rewrite table anyway */
      skip_build = (tab->newvals != NIL);
      /* suppress notices when rebuilding existing index */
      quiet = is_rebuild;

      /* The IndexStmt has already been through transformIndexStmt */

      DefineIndex(stmt->relation, /* relation */
                        stmt->idxname,    /* index name */
                        InvalidOid,       /* no predefined OID */
                        stmt->accessMethod,           /* am name */
                        stmt->tableSpace,
                        stmt->indexParams,            /* parameters */
                        (Expr *) stmt->whereClause,
                        stmt->options,
                        stmt->unique,
                        stmt->primary,
                        stmt->isconstraint,
                        true,             /* is_alter_table */
                        check_rights,
                        skip_build,
                        quiet,
                        false);
}

/*
 * ALTER TABLE ADD CONSTRAINT
 */
static void
ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                              Node *newConstraint, bool recurse)
{
      switch (nodeTag(newConstraint))
      {
            case T_Constraint:
                  {
                        Constraint *constr = (Constraint *) newConstraint;

                        /*
                         * Currently, we only expect to see CONSTR_CHECK nodes
                         * arriving here (see the preprocessing done in
                         * parse_utilcmd.c).  Use a switch anyway to make it easier to
                         * add more code later.
                         */
                        switch (constr->contype)
                        {
                              case CONSTR_CHECK:
                                    ATAddCheckConstraint(wqueue, tab, rel,
                                                                   constr, recurse, false);
                                    break;
                              default:
                                    elog(ERROR, "unrecognized constraint type: %d",
                                           (int) constr->contype);
                        }
                        break;
                  }
            case T_FkConstraint:
                  {
                        FkConstraint *fkconstraint = (FkConstraint *) newConstraint;

                        /*
                         * Note that we currently never recurse for FK constraints, so
                         * the "recurse" flag is silently ignored.
                         *
                         * Assign or validate constraint name
                         */
                        if (fkconstraint->constr_name)
                        {
                              if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
                                                                   RelationGetRelid(rel),
                                                                   RelationGetNamespace(rel),
                                                                   fkconstraint->constr_name))
                                    ereport(ERROR,
                                                (errcode(ERRCODE_DUPLICATE_OBJECT),
                                                 errmsg("constraint \"%s\" for relation \"%s\" already exists",
                                                            fkconstraint->constr_name,
                                                            RelationGetRelationName(rel))));
                        }
                        else
                              fkconstraint->constr_name =
                                    ChooseConstraintName(RelationGetRelationName(rel),
                                                      strVal(linitial(fkconstraint->fk_attrs)),
                                                                   "fkey",
                                                                   RelationGetNamespace(rel),
                                                                   NIL);

                        ATAddForeignKeyConstraint(tab, rel, fkconstraint);

                        break;
                  }
            default:
                  elog(ERROR, "unrecognized node type: %d",
                         (int) nodeTag(newConstraint));
      }
}

/*
 * Add a check constraint to a single table and its children
 *
 * Subroutine for ATExecAddConstraint.
 *
 * We must recurse to child tables during execution, rather than using
 * ALTER TABLE's normal prep-time recursion.  The reason is that all the
 * constraints *must* be given the same name, else they won't be seen as
 * related later.  If the user didn't explicitly specify a name, then
 * AddRelationNewConstraints would normally assign different names to the
 * child constraints.  To fix that, we must capture the name assigned at
 * the parent table and pass that down.
 */
static void
ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
                               Constraint *constr, bool recurse, bool recursing)
{
      List     *newcons;
      ListCell   *lcon;
      List     *children;
      ListCell   *child;

      /* At top level, permission check was done in ATPrepCmd, else do it */
      if (recursing)
            ATSimplePermissions(rel, false);

      /*
       * Call AddRelationNewConstraints to do the work, making sure it works on
       * a copy of the Constraint so transformExpr can't modify the original. It
       * returns a list of cooked constraints.
       *
       * If the constraint ends up getting merged with a pre-existing one, it's
       * omitted from the returned list, which is what we want: we do not need
       * to do any validation work.  That can only happen at child tables,
       * though, since we disallow merging at the top level.
       */
      newcons = AddRelationNewConstraints(rel, NIL,
                                                            list_make1(copyObject(constr)),
                                                            recursing, !recursing);

      /* Add each constraint to Phase 3's queue */
      foreach(lcon, newcons)
      {
            CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon);
            NewConstraint *newcon;

            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = ccon->name;
            newcon->contype = ccon->contype;
            /* ExecQual wants implicit-AND format */
            newcon->qual = (Node *) make_ands_implicit((Expr *) ccon->expr);

            tab->constraints = lappend(tab->constraints, newcon);

            /* Save the actually assigned name if it was defaulted */
            if (constr->name == NULL)
                  constr->name = ccon->name;
      }

      /* At this point we must have a locked-down name to use */
      Assert(constr->name != NULL);

      /* Advance command counter in case same table is visited multiple times */
      CommandCounterIncrement();

      /*
       * Propagate to children as appropriate.  Unlike most other ALTER
       * routines, we have to do this one level of recursion at a time; we can't
       * use find_all_inheritors to do it in one pass.
       */
      children = find_inheritance_children(RelationGetRelid(rel),
                                                             AccessExclusiveLock);

      /*
       * If we are told not to recurse, there had better not be any child
       * tables; else the addition would put them out of step.
       */
      if (children && !recurse)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("constraint must be added to child tables too")));

      foreach(child, children)
      {
            Oid               childrelid = lfirst_oid(child);
            Relation    childrel;
            AlteredTableInfo *childtab;

            /* find_inheritance_children already got lock */
            childrel = heap_open(childrelid, NoLock);
            CheckTableNotInUse(childrel, "ALTER TABLE");

            /* Find or create work queue entry for this table */
            childtab = ATGetQueueEntry(wqueue, childrel);

            /* Recurse to child */
            ATAddCheckConstraint(wqueue, childtab, childrel,
                                           constr, recurse, true);

            heap_close(childrel, NoLock);
      }
}

/*
 * Add a foreign-key constraint to a single table
 *
 * Subroutine for ATExecAddConstraint.    Must already hold exclusive
 * lock on the rel, and have done appropriate validity checks for it.
 * We do permissions checks here, however.
 */
static void
ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel,
                                      FkConstraint *fkconstraint)
{
      Relation    pkrel;
      int16       pkattnum[INDEX_MAX_KEYS];
      int16       fkattnum[INDEX_MAX_KEYS];
      Oid               pktypoid[INDEX_MAX_KEYS];
      Oid               fktypoid[INDEX_MAX_KEYS];
      Oid               opclasses[INDEX_MAX_KEYS];
      Oid               pfeqoperators[INDEX_MAX_KEYS];
      Oid               ppeqoperators[INDEX_MAX_KEYS];
      Oid               ffeqoperators[INDEX_MAX_KEYS];
      int               i;
      int               numfks,
                        numpks;
      Oid               indexOid;
      Oid               constrOid;

      /*
       * Grab an exclusive lock on the pk table, so that someone doesn't delete
       * rows out from under us. (Although a lesser lock would do for that
       * purpose, we'll need exclusive lock anyway to add triggers to the pk
       * table; trying to start with a lesser lock will just create a risk of
       * deadlock.)
       */
      pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock);

      /*
       * Validity checks (permission checks wait till we have the column
       * numbers)
       */
      if (pkrel->rd_rel->relkind != RELKIND_RELATION)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("referenced relation \"%s\" is not a table",
                                    RelationGetRelationName(pkrel))));

      if (!allowSystemTableMods && IsSystemRelation(pkrel))
            ereport(ERROR,
                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                         errmsg("permission denied: \"%s\" is a system catalog",
                                    RelationGetRelationName(pkrel))));

      /*
       * Disallow reference from permanent table to temp table or vice versa.
       * (The ban on perm->temp is for fairly obvious reasons.  The ban on
       * temp->perm is because other backends might need to run the RI triggers
       * on the perm table, but they can't reliably see tuples the owning
       * backend has created in the temp table, because non-shared buffers are
       * used for temp tables.)
       */
      if (pkrel->rd_istemp)
      {
            if (!rel->rd_istemp)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("cannot reference temporary table from permanent table constraint")));
      }
      else
      {
            if (rel->rd_istemp)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("cannot reference permanent table from temporary table constraint")));
      }

      /*
       * Look up the referencing attributes to make sure they exist, and record
       * their attnums and type OIDs.
       */
      MemSet(pkattnum, 0, sizeof(pkattnum));
      MemSet(fkattnum, 0, sizeof(fkattnum));
      MemSet(pktypoid, 0, sizeof(pktypoid));
      MemSet(fktypoid, 0, sizeof(fktypoid));
      MemSet(opclasses, 0, sizeof(opclasses));
      MemSet(pfeqoperators, 0, sizeof(pfeqoperators));
      MemSet(ppeqoperators, 0, sizeof(ppeqoperators));
      MemSet(ffeqoperators, 0, sizeof(ffeqoperators));

      numfks = transformColumnNameList(RelationGetRelid(rel),
                                                       fkconstraint->fk_attrs,
                                                       fkattnum, fktypoid);

      /*
       * If the attribute list for the referenced table was omitted, lookup the
       * definition of the primary key and use it.  Otherwise, validate the
       * supplied attribute list.  In either case, discover the index OID and
       * index opclasses, and the attnums and type OIDs of the attributes.
       */
      if (fkconstraint->pk_attrs == NIL)
      {
            numpks = transformFkeyGetPrimaryKey(pkrel, &indexOid,
                                                                  &fkconstraint->pk_attrs,
                                                                  pkattnum, pktypoid,
                                                                  opclasses);
      }
      else
      {
            numpks = transformColumnNameList(RelationGetRelid(pkrel),
                                                             fkconstraint->pk_attrs,
                                                             pkattnum, pktypoid);
            /* Look for an index matching the column list */
            indexOid = transformFkeyCheckAttrs(pkrel, numpks, pkattnum,
                                                               opclasses);
      }

      /*
       * Now we can check permissions.
       */
      checkFkeyPermissions(pkrel, pkattnum, numpks);
      checkFkeyPermissions(rel, fkattnum, numfks);

      /*
       * Look up the equality operators to use in the constraint.
       *
       * Note that we have to be careful about the difference between the actual
       * PK column type and the opclass' declared input type, which might be
       * only binary-compatible with it.  The declared opcintype is the right
       * thing to probe pg_amop with.
       */
      if (numfks != numpks)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FOREIGN_KEY),
                         errmsg("number of referencing and referenced columns for foreign key disagree")));

      for (i = 0; i < numpks; i++)
      {
            Oid               pktype = pktypoid[i];
            Oid               fktype = fktypoid[i];
            Oid               fktyped;
            HeapTuple   cla_ht;
            Form_pg_opclass cla_tup;
            Oid               amid;
            Oid               opfamily;
            Oid               opcintype;
            Oid               pfeqop;
            Oid               ppeqop;
            Oid               ffeqop;
            int16       eqstrategy;

            /* We need several fields out of the pg_opclass entry */
            cla_ht = SearchSysCache(CLAOID,
                                                ObjectIdGetDatum(opclasses[i]),
                                                0, 0, 0);
            if (!HeapTupleIsValid(cla_ht))
                  elog(ERROR, "cache lookup failed for opclass %u", opclasses[i]);
            cla_tup = (Form_pg_opclass) GETSTRUCT(cla_ht);
            amid = cla_tup->opcmethod;
            opfamily = cla_tup->opcfamily;
            opcintype = cla_tup->opcintype;
            ReleaseSysCache(cla_ht);

            /*
             * Check it's a btree; currently this can never fail since no other
             * index AMs support unique indexes.  If we ever did have other types
             * of unique indexes, we'd need a way to determine which operator
             * strategy number is equality.  (Is it reasonable to insist that
             * every such index AM use btree's number for equality?)
             */
            if (amid != BTREE_AM_OID)
                  elog(ERROR, "only b-tree indexes are supported for foreign keys");
            eqstrategy = BTEqualStrategyNumber;

            /*
             * There had better be a primary equality operator for the index.
             * We'll use it for PK = PK comparisons.
             */
            ppeqop = get_opfamily_member(opfamily, opcintype, opcintype,
                                                       eqstrategy);

            if (!OidIsValid(ppeqop))
                  elog(ERROR, "missing operator %d(%u,%u) in opfamily %u",
                         eqstrategy, opcintype, opcintype, opfamily);

            /*
             * Are there equality operators that take exactly the FK type? Assume
             * we should look through any domain here.
             */
            fktyped = getBaseType(fktype);

            pfeqop = get_opfamily_member(opfamily, opcintype, fktyped,
                                                       eqstrategy);
            if (OidIsValid(pfeqop))
                  ffeqop = get_opfamily_member(opfamily, fktyped, fktyped,
                                                             eqstrategy);
            else
                  ffeqop = InvalidOid;    /* keep compiler quiet */

            if (!(OidIsValid(pfeqop) && OidIsValid(ffeqop)))
            {
                  /*
                   * Otherwise, look for an implicit cast from the FK type to the
                   * opcintype, and if found, use the primary equality operator.
                   * This is a bit tricky because opcintype might be a polymorphic
                   * type such as ANYARRAY or ANYENUM; so what we have to test is
                   * whether the two actual column types can be concurrently cast to
                   * that type.  (Otherwise, we'd fail to reject combinations such
                   * as int[] and point[].)
                   */
                  Oid               input_typeids[2];
                  Oid               target_typeids[2];

                  input_typeids[0] = pktype;
                  input_typeids[1] = fktype;
                  target_typeids[0] = opcintype;
                  target_typeids[1] = opcintype;
                  if (can_coerce_type(2, input_typeids, target_typeids,
                                                COERCION_IMPLICIT))
                        pfeqop = ffeqop = ppeqop;
            }

            if (!(OidIsValid(pfeqop) && OidIsValid(ffeqop)))
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("foreign key constraint \"%s\" "
                                          "cannot be implemented",
                                          fkconstraint->constr_name),
                               errdetail("Key columns \"%s\" and \"%s\" "
                                             "are of incompatible types: %s and %s.",
                                             strVal(list_nth(fkconstraint->fk_attrs, i)),
                                             strVal(list_nth(fkconstraint->pk_attrs, i)),
                                             format_type_be(fktype),
                                             format_type_be(pktype))));

            pfeqoperators[i] = pfeqop;
            ppeqoperators[i] = ppeqop;
            ffeqoperators[i] = ffeqop;
      }

      /*
       * Record the FK constraint in pg_constraint.
       */
      constrOid = CreateConstraintEntry(fkconstraint->constr_name,
                                                        RelationGetNamespace(rel),
                                                        CONSTRAINT_FOREIGN,
                                                        fkconstraint->deferrable,
                                                        fkconstraint->initdeferred,
                                                        RelationGetRelid(rel),
                                                        fkattnum,
                                                        numfks,
                                                        InvalidOid,           /* not a domain
                                                                                     * constraint */
                                                        RelationGetRelid(pkrel),
                                                        pkattnum,
                                                        pfeqoperators,
                                                        ppeqoperators,
                                                        ffeqoperators,
                                                        numpks,
                                                        fkconstraint->fk_upd_action,
                                                        fkconstraint->fk_del_action,
                                                        fkconstraint->fk_matchtype,
                                                        indexOid,
                                                        NULL,           /* no check constraint */
                                                        NULL,
                                                        NULL,
                                                        true,           /* islocal */
                                                        0);       /* inhcount */

      /*
       * Create the triggers that will enforce the constraint.
       */
      createForeignKeyTriggers(rel, fkconstraint, constrOid);

      /*
       * Tell Phase 3 to check that the constraint is satisfied by existing rows
       * (we can skip this during table creation).
       */
      if (!fkconstraint->skip_validation)
      {
            NewConstraint *newcon;

            newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
            newcon->name = fkconstraint->constr_name;
            newcon->contype = CONSTR_FOREIGN;
            newcon->refrelid = RelationGetRelid(pkrel);
            newcon->conid = constrOid;
            newcon->qual = (Node *) fkconstraint;

            tab->constraints = lappend(tab->constraints, newcon);
      }

      /*
       * Close pk table, but keep lock until we've committed.
       */
      heap_close(pkrel, NoLock);
}


/*
 * transformColumnNameList - transform list of column names
 *
 * Lookup each name and return its attnum and type OID
 */
static int
transformColumnNameList(Oid relId, List *colList,
                                    int16 *attnums, Oid *atttypids)
{
      ListCell   *l;
      int               attnum;

      attnum = 0;
      foreach(l, colList)
      {
            char     *attname = strVal(lfirst(l));
            HeapTuple   atttuple;

            atttuple = SearchSysCacheAttName(relId, attname);
            if (!HeapTupleIsValid(atttuple))
                  ereport(ERROR,
                              (errcode(ERRCODE_UNDEFINED_COLUMN),
                               errmsg("column \"%s\" referenced in foreign key constraint does not exist",
                                          attname)));
            if (attnum >= INDEX_MAX_KEYS)
                  ereport(ERROR,
                              (errcode(ERRCODE_TOO_MANY_COLUMNS),
                               errmsg("cannot have more than %d keys in a foreign key",
                                          INDEX_MAX_KEYS)));
            attnums[attnum] = ((Form_pg_attribute) GETSTRUCT(atttuple))->attnum;
            atttypids[attnum] = ((Form_pg_attribute) GETSTRUCT(atttuple))->atttypid;
            ReleaseSysCache(atttuple);
            attnum++;
      }

      return attnum;
}

/*
 * transformFkeyGetPrimaryKey -
 *
 *    Look up the names, attnums, and types of the primary key attributes
 *    for the pkrel.    Also return the index OID and index opclasses of the
 *    index supporting the primary key.
 *
 *    All parameters except pkrel are output parameters.    Also, the function
 *    return value is the number of attributes in the primary key.
 *
 *    Used when the column list in the REFERENCES specification is omitted.
 */
static int
transformFkeyGetPrimaryKey(Relation pkrel, Oid *indexOid,
                                       List **attnamelist,
                                       int16 *attnums, Oid *atttypids,
                                       Oid *opclasses)
{
      List     *indexoidlist;
      ListCell   *indexoidscan;
      HeapTuple   indexTuple = NULL;
      Form_pg_index indexStruct = NULL;
      Datum       indclassDatum;
      bool        isnull;
      oidvector  *indclass;
      int               i;

      /*
       * Get the list of index OIDs for the table from the relcache, and look up
       * each one in the pg_index syscache until we find one marked primary key
       * (hopefully there isn't more than one such).
       */
      *indexOid = InvalidOid;

      indexoidlist = RelationGetIndexList(pkrel);

      foreach(indexoidscan, indexoidlist)
      {
            Oid               indexoid = lfirst_oid(indexoidscan);

            indexTuple = SearchSysCache(INDEXRELID,
                                                      ObjectIdGetDatum(indexoid),
                                                      0, 0, 0);
            if (!HeapTupleIsValid(indexTuple))
                  elog(ERROR, "cache lookup failed for index %u", indexoid);
            indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);
            if (indexStruct->indisprimary)
            {
                  *indexOid = indexoid;
                  break;
            }
            ReleaseSysCache(indexTuple);
      }

      list_free(indexoidlist);

      /*
       * Check that we found it
       */
      if (!OidIsValid(*indexOid))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("there is no primary key for referenced table \"%s\"",
                                    RelationGetRelationName(pkrel))));

      /* Must get indclass the hard way */
      indclassDatum = SysCacheGetAttr(INDEXRELID, indexTuple,
                                                      Anum_pg_index_indclass, &isnull);
      Assert(!isnull);
      indclass = (oidvector *) DatumGetPointer(indclassDatum);

      /*
       * Now build the list of PK attributes from the indkey definition (we
       * assume a primary key cannot have expressional elements)
       */
      *attnamelist = NIL;
      for (i = 0; i < indexStruct->indnatts; i++)
      {
            int               pkattno = indexStruct->indkey.values[i];

            attnums[i] = pkattno;
            atttypids[i] = attnumTypeId(pkrel, pkattno);
            opclasses[i] = indclass->values[i];
            *attnamelist = lappend(*attnamelist,
                     makeString(pstrdup(NameStr(*attnumAttName(pkrel, pkattno)))));
      }

      ReleaseSysCache(indexTuple);

      return i;
}

/*
 * transformFkeyCheckAttrs -
 *
 *    Make sure that the attributes of a referenced table belong to a unique
 *    (or primary key) constraint.  Return the OID of the index supporting
 *    the constraint, as well as the opclasses associated with the index
 *    columns.
 */
static Oid
transformFkeyCheckAttrs(Relation pkrel,
                                    int numattrs, int16 *attnums,
                                    Oid *opclasses) /* output parameter */
{
      Oid               indexoid = InvalidOid;
      bool        found = false;
      List     *indexoidlist;
      ListCell   *indexoidscan;

      /*
       * Get the list of index OIDs for the table from the relcache, and look up
       * each one in the pg_index syscache, and match unique indexes to the list
       * of attnums we are given.
       */
      indexoidlist = RelationGetIndexList(pkrel);

      foreach(indexoidscan, indexoidlist)
      {
            HeapTuple   indexTuple;
            Form_pg_index indexStruct;
            int               i,
                              j;

            indexoid = lfirst_oid(indexoidscan);
            indexTuple = SearchSysCache(INDEXRELID,
                                                      ObjectIdGetDatum(indexoid),
                                                      0, 0, 0);
            if (!HeapTupleIsValid(indexTuple))
                  elog(ERROR, "cache lookup failed for index %u", indexoid);
            indexStruct = (Form_pg_index) GETSTRUCT(indexTuple);

            /*
             * Must have the right number of columns; must be unique and not a
             * partial index; forget it if there are any expressions, too
             */
            if (indexStruct->indnatts == numattrs &&
                  indexStruct->indisunique &&
                  heap_attisnull(indexTuple, Anum_pg_index_indpred) &&
                  heap_attisnull(indexTuple, Anum_pg_index_indexprs))
            {
                  /* Must get indclass the hard way */
                  Datum       indclassDatum;
                  bool        isnull;
                  oidvector  *indclass;

                  indclassDatum = SysCacheGetAttr(INDEXRELID, indexTuple,
                                                                  Anum_pg_index_indclass, &isnull);
                  Assert(!isnull);
                  indclass = (oidvector *) DatumGetPointer(indclassDatum);

                  /*
                   * The given attnum list may match the index columns in any order.
                   * Check that each list is a subset of the other.
                   */
                  for (i = 0; i < numattrs; i++)
                  {
                        found = false;
                        for (j = 0; j < numattrs; j++)
                        {
                              if (attnums[i] == indexStruct->indkey.values[j])
                              {
                                    found = true;
                                    break;
                              }
                        }
                        if (!found)
                              break;
                  }
                  if (found)
                  {
                        for (i = 0; i < numattrs; i++)
                        {
                              found = false;
                              for (j = 0; j < numattrs; j++)
                              {
                                    if (attnums[j] == indexStruct->indkey.values[i])
                                    {
                                          opclasses[j] = indclass->values[i];
                                          found = true;
                                          break;
                                    }
                              }
                              if (!found)
                                    break;
                        }
                  }
            }
            ReleaseSysCache(indexTuple);
            if (found)
                  break;
      }

      if (!found)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_FOREIGN_KEY),
                         errmsg("there is no unique constraint matching given keys for referenced table \"%s\"",
                                    RelationGetRelationName(pkrel))));

      list_free(indexoidlist);

      return indexoid;
}

/* Permissions checks for ADD FOREIGN KEY */
static void
checkFkeyPermissions(Relation rel, int16 *attnums, int natts)
{
      Oid               roleid = GetUserId();
      AclResult   aclresult;
      int               i;

      /* Okay if we have relation-level REFERENCES permission */
      aclresult = pg_class_aclcheck(RelationGetRelid(rel), roleid,
                                                  ACL_REFERENCES);
      if (aclresult == ACLCHECK_OK)
            return;
      /* Else we must have REFERENCES on each column */
      for (i = 0; i < natts; i++)
      {
            aclresult = pg_attribute_aclcheck(RelationGetRelid(rel), attnums[i],
                                                              roleid, ACL_REFERENCES);
            if (aclresult != ACLCHECK_OK)
                  aclcheck_error(aclresult, ACL_KIND_CLASS,
                                       RelationGetRelationName(rel));
      }
}

/*
 * Scan the existing rows in a table to verify they meet a proposed FK
 * constraint.
 *
 * Caller must have opened and locked both relations.
 */
static void
validateForeignKeyConstraint(FkConstraint *fkconstraint,
                                           Relation rel,
                                           Relation pkrel,
                                           Oid constraintOid)
{
      HeapScanDesc scan;
      HeapTuple   tuple;
      Trigger           trig;

      /*
       * Build a trigger call structure; we'll need it either way.
       */
      MemSet(&trig, 0, sizeof(trig));
      trig.tgoid = InvalidOid;
      trig.tgname = fkconstraint->constr_name;
      trig.tgenabled = TRIGGER_FIRES_ON_ORIGIN;
      trig.tgisconstraint = TRUE;
      trig.tgconstrrelid = RelationGetRelid(pkrel);
      trig.tgconstraint = constraintOid;
      trig.tgdeferrable = FALSE;
      trig.tginitdeferred = FALSE;
      /* we needn't fill in tgargs */

      /*
       * See if we can do it with a single LEFT JOIN query.  A FALSE result
       * indicates we must proceed with the fire-the-trigger method.
       */
      if (RI_Initial_Check(&trig, rel, pkrel))
            return;

      /*
       * Scan through each tuple, calling RI_FKey_check_ins (insert trigger) as
       * if that tuple had just been inserted.  If any of those fail, it should
       * ereport(ERROR) and that's that.
       */
      scan = heap_beginscan(rel, SnapshotNow, 0, NULL);

      while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
      {
            FunctionCallInfoData fcinfo;
            TriggerData trigdata;

            /*
             * Make a call to the trigger function
             *
             * No parameters are passed, but we do set a context
             */
            MemSet(&fcinfo, 0, sizeof(fcinfo));

            /*
             * We assume RI_FKey_check_ins won't look at flinfo...
             */
            trigdata.type = T_TriggerData;
            trigdata.tg_event = TRIGGER_EVENT_INSERT | TRIGGER_EVENT_ROW;
            trigdata.tg_relation = rel;
            trigdata.tg_trigtuple = tuple;
            trigdata.tg_newtuple = NULL;
            trigdata.tg_trigger = &trig;
            trigdata.tg_trigtuplebuf = scan->rs_cbuf;
            trigdata.tg_newtuplebuf = InvalidBuffer;

            fcinfo.context = (Node *) &trigdata;

            RI_FKey_check_ins(&fcinfo);
      }

      heap_endscan(scan);
}

static void
CreateFKCheckTrigger(RangeVar *myRel, FkConstraint *fkconstraint,
                               Oid constraintOid, bool on_insert)
{
      CreateTrigStmt *fk_trigger;

      fk_trigger = makeNode(CreateTrigStmt);
      fk_trigger->trigname = fkconstraint->constr_name;
      fk_trigger->relation = myRel;
      fk_trigger->before = false;
      fk_trigger->row = true;

      /* Either ON INSERT or ON UPDATE */
      if (on_insert)
      {
            fk_trigger->funcname = SystemFuncName("RI_FKey_check_ins");
            fk_trigger->events = TRIGGER_TYPE_INSERT;
      }
      else
      {
            fk_trigger->funcname = SystemFuncName("RI_FKey_check_upd");
            fk_trigger->events = TRIGGER_TYPE_UPDATE;
      }

      fk_trigger->isconstraint = true;
      fk_trigger->deferrable = fkconstraint->deferrable;
      fk_trigger->initdeferred = fkconstraint->initdeferred;
      fk_trigger->constrrel = fkconstraint->pktable;
      fk_trigger->args = NIL;

      (void) CreateTrigger(fk_trigger, constraintOid, false);

      /* Make changes-so-far visible */
      CommandCounterIncrement();
}

/*
 * Create the triggers that implement an FK constraint.
 */
static void
createForeignKeyTriggers(Relation rel, FkConstraint *fkconstraint,
                                     Oid constraintOid)
{
      RangeVar   *myRel;
      CreateTrigStmt *fk_trigger;

      /*
       * Reconstruct a RangeVar for my relation (not passed in, unfortunately).
       */
      myRel = makeRangeVar(get_namespace_name(RelationGetNamespace(rel)),
                                     pstrdup(RelationGetRelationName(rel)),
                                     -1);

      /* Make changes-so-far visible */
      CommandCounterIncrement();

      /*
       * Build and execute a CREATE CONSTRAINT TRIGGER statement for the CHECK
       * action for both INSERTs and UPDATEs on the referencing table.
       */
      CreateFKCheckTrigger(myRel, fkconstraint, constraintOid, true);
      CreateFKCheckTrigger(myRel, fkconstraint, constraintOid, false);

      /*
       * Build and execute a CREATE CONSTRAINT TRIGGER statement for the ON
       * DELETE action on the referenced table.
       */
      fk_trigger = makeNode(CreateTrigStmt);
      fk_trigger->trigname = fkconstraint->constr_name;
      fk_trigger->relation = fkconstraint->pktable;
      fk_trigger->before = false;
      fk_trigger->row = true;
      fk_trigger->events = TRIGGER_TYPE_DELETE;
      fk_trigger->isconstraint = true;
      fk_trigger->constrrel = myRel;
      switch (fkconstraint->fk_del_action)
      {
            case FKCONSTR_ACTION_NOACTION:
                  fk_trigger->deferrable = fkconstraint->deferrable;
                  fk_trigger->initdeferred = fkconstraint->initdeferred;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_noaction_del");
                  break;
            case FKCONSTR_ACTION_RESTRICT:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_restrict_del");
                  break;
            case FKCONSTR_ACTION_CASCADE:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_cascade_del");
                  break;
            case FKCONSTR_ACTION_SETNULL:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_setnull_del");
                  break;
            case FKCONSTR_ACTION_SETDEFAULT:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_setdefault_del");
                  break;
            default:
                  elog(ERROR, "unrecognized FK action type: %d",
                         (int) fkconstraint->fk_del_action);
                  break;
      }
      fk_trigger->args = NIL;

      (void) CreateTrigger(fk_trigger, constraintOid, false);

      /* Make changes-so-far visible */
      CommandCounterIncrement();

      /*
       * Build and execute a CREATE CONSTRAINT TRIGGER statement for the ON
       * UPDATE action on the referenced table.
       */
      fk_trigger = makeNode(CreateTrigStmt);
      fk_trigger->trigname = fkconstraint->constr_name;
      fk_trigger->relation = fkconstraint->pktable;
      fk_trigger->before = false;
      fk_trigger->row = true;
      fk_trigger->events = TRIGGER_TYPE_UPDATE;
      fk_trigger->isconstraint = true;
      fk_trigger->constrrel = myRel;
      switch (fkconstraint->fk_upd_action)
      {
            case FKCONSTR_ACTION_NOACTION:
                  fk_trigger->deferrable = fkconstraint->deferrable;
                  fk_trigger->initdeferred = fkconstraint->initdeferred;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_noaction_upd");
                  break;
            case FKCONSTR_ACTION_RESTRICT:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_restrict_upd");
                  break;
            case FKCONSTR_ACTION_CASCADE:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_cascade_upd");
                  break;
            case FKCONSTR_ACTION_SETNULL:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_setnull_upd");
                  break;
            case FKCONSTR_ACTION_SETDEFAULT:
                  fk_trigger->deferrable = false;
                  fk_trigger->initdeferred = false;
                  fk_trigger->funcname = SystemFuncName("RI_FKey_setdefault_upd");
                  break;
            default:
                  elog(ERROR, "unrecognized FK action type: %d",
                         (int) fkconstraint->fk_upd_action);
                  break;
      }
      fk_trigger->args = NIL;

      (void) CreateTrigger(fk_trigger, constraintOid, false);
}

/*
 * ALTER TABLE DROP CONSTRAINT
 *
 * Like DROP COLUMN, we can't use the normal ALTER TABLE recursion mechanism.
 */
static void
ATExecDropConstraint(Relation rel, const char *constrName,
                               DropBehavior behavior,
                               bool recurse, bool recursing)
{
      List     *children;
      ListCell   *child;
      Relation    conrel;
      Form_pg_constraint con;
      SysScanDesc scan;
      ScanKeyData key;
      HeapTuple   tuple;
      bool        found = false;
      bool        is_check_constraint = false;

      /* At top level, permission check was done in ATPrepCmd, else do it */
      if (recursing)
            ATSimplePermissions(rel, false);

      conrel = heap_open(ConstraintRelationId, RowExclusiveLock);

      /*
       * Find and drop the target constraint
       */
      ScanKeyInit(&key,
                        Anum_pg_constraint_conrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      scan = systable_beginscan(conrel, ConstraintRelidIndexId,
                                            true, SnapshotNow, 1, &key);

      while (HeapTupleIsValid(tuple = systable_getnext(scan)))
      {
            ObjectAddress conobj;

            con = (Form_pg_constraint) GETSTRUCT(tuple);

            if (strcmp(NameStr(con->conname), constrName) != 0)
                  continue;

            /* Don't drop inherited constraints */
            if (con->coninhcount > 0 && !recursing)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                               errmsg("cannot drop inherited constraint \"%s\" of relation \"%s\"",
                                          constrName, RelationGetRelationName(rel))));

            /* Right now only CHECK constraints can be inherited */
            if (con->contype == CONSTRAINT_CHECK)
                  is_check_constraint = true;

            /*
             * Perform the actual constraint deletion
             */
            conobj.classId = ConstraintRelationId;
            conobj.objectId = HeapTupleGetOid(tuple);
            conobj.objectSubId = 0;

            performDeletion(&conobj, behavior);

            found = true;
      }

      systable_endscan(scan);

      if (!found)
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                                    constrName, RelationGetRelationName(rel))));

      /*
       * Propagate to children as appropriate.  Unlike most other ALTER
       * routines, we have to do this one level of recursion at a time; we can't
       * use find_all_inheritors to do it in one pass.
       */
      if (is_check_constraint)
            children = find_inheritance_children(RelationGetRelid(rel),
                                                                   AccessExclusiveLock);
      else
            children = NIL;

      foreach(child, children)
      {
            Oid               childrelid = lfirst_oid(child);
            Relation    childrel;

            /* find_inheritance_children already got lock */
            childrel = heap_open(childrelid, NoLock);
            CheckTableNotInUse(childrel, "ALTER TABLE");

            ScanKeyInit(&key,
                              Anum_pg_constraint_conrelid,
                              BTEqualStrategyNumber, F_OIDEQ,
                              ObjectIdGetDatum(childrelid));
            scan = systable_beginscan(conrel, ConstraintRelidIndexId,
                                                  true, SnapshotNow, 1, &key);

            found = false;

            while (HeapTupleIsValid(tuple = systable_getnext(scan)))
            {
                  HeapTuple   copy_tuple;

                  con = (Form_pg_constraint) GETSTRUCT(tuple);

                  /* Right now only CHECK constraints can be inherited */
                  if (con->contype != CONSTRAINT_CHECK)
                        continue;

                  if (strcmp(NameStr(con->conname), constrName) != 0)
                        continue;

                  found = true;

                  if (con->coninhcount <= 0)    /* shouldn't happen */
                        elog(ERROR, "relation %u has non-inherited constraint \"%s\"",
                               childrelid, constrName);

                  copy_tuple = heap_copytuple(tuple);
                  con = (Form_pg_constraint) GETSTRUCT(copy_tuple);

                  if (recurse)
                  {
                        /*
                         * If the child constraint has other definition sources, just
                         * decrement its inheritance count; if not, recurse to delete
                         * it.
                         */
                        if (con->coninhcount == 1 && !con->conislocal)
                        {
                              /* Time to delete this child constraint, too */
                              ATExecDropConstraint(childrel, constrName, behavior,
                                                             true, true);
                        }
                        else
                        {
                              /* Child constraint must survive my deletion */
                              con->coninhcount--;
                              simple_heap_update(conrel, &copy_tuple->t_self, copy_tuple);
                              CatalogUpdateIndexes(conrel, copy_tuple);

                              /* Make update visible */
                              CommandCounterIncrement();
                        }
                  }
                  else
                  {
                        /*
                         * If we were told to drop ONLY in this table (no recursion),
                         * we need to mark the inheritors' constraints as locally
                         * defined rather than inherited.
                         */
                        con->coninhcount--;
                        con->conislocal = true;

                        simple_heap_update(conrel, &copy_tuple->t_self, copy_tuple);
                        CatalogUpdateIndexes(conrel, copy_tuple);

                        /* Make update visible */
                        CommandCounterIncrement();
                  }

                  heap_freetuple(copy_tuple);
            }

            systable_endscan(scan);

            if (!found)
                  ereport(ERROR,
                              (errcode(ERRCODE_UNDEFINED_OBJECT),
                        errmsg("constraint \"%s\" of relation \"%s\" does not exist",
                                 constrName,
                                 RelationGetRelationName(childrel))));

            heap_close(childrel, NoLock);
      }

      heap_close(conrel, RowExclusiveLock);
}

/*
 * ALTER COLUMN TYPE
 */
static void
ATPrepAlterColumnType(List **wqueue,
                                AlteredTableInfo *tab, Relation rel,
                                bool recurse, bool recursing,
                                AlterTableCmd *cmd)
{
      char     *colName = cmd->name;
      TypeName   *typename = (TypeName *) cmd->def;
      HeapTuple   tuple;
      Form_pg_attribute attTup;
      AttrNumber  attnum;
      Oid               targettype;
      int32       targettypmod;
      Node     *transform;
      NewColumnValue *newval;
      ParseState *pstate = make_parsestate(NULL);

      /* lookup the attribute so we can check inheritance status */
      tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
      if (!HeapTupleIsValid(tuple))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));
      attTup = (Form_pg_attribute) GETSTRUCT(tuple);
      attnum = attTup->attnum;

      /* Can't alter a system attribute */
      if (attnum <= 0)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter system column \"%s\"",
                                    colName)));

      /* Don't alter inherited columns */
      if (attTup->attinhcount > 0 && !recursing)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("cannot alter inherited column \"%s\"",
                                    colName)));

      /* Look up the target type */
      targettype = typenameTypeId(NULL, typename, &targettypmod);

      /* make sure datatype is legal for a column */
      CheckAttributeType(colName, targettype);

      /*
       * Set up an expression to transform the old data value to the new type.
       * If a USING option was given, transform and use that expression, else
       * just take the old value and try to coerce it.  We do this first so that
       * type incompatibility can be detected before we waste effort, and
       * because we need the expression to be parsed against the original table
       * rowtype.
       */
      if (cmd->transform)
      {
            RangeTblEntry *rte;

            /* Expression must be able to access vars of old table */
            rte = addRangeTableEntryForRelation(pstate,
                                                                  rel,
                                                                  NULL,
                                                                  false,
                                                                  true);
            addRTEtoQuery(pstate, rte, false, true, true);

            transform = transformExpr(pstate, cmd->transform);

            /* It can't return a set */
            if (expression_returns_set(transform))
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("transform expression must not return a set")));

            /* No subplans or aggregates, either... */
            if (pstate->p_hasSubLinks)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("cannot use subquery in transform expression")));
            if (pstate->p_hasAggs)
                  ereport(ERROR,
                              (errcode(ERRCODE_GROUPING_ERROR),
                  errmsg("cannot use aggregate function in transform expression")));
            if (pstate->p_hasWindowFuncs)
                  ereport(ERROR,
                              (errcode(ERRCODE_WINDOWING_ERROR),
                    errmsg("cannot use window function in transform expression")));
      }
      else
      {
            transform = (Node *) makeVar(1, attnum,
                                                       attTup->atttypid, attTup->atttypmod,
                                                       0);
      }

      transform = coerce_to_target_type(pstate,
                                                        transform, exprType(transform),
                                                        targettype, targettypmod,
                                                        COERCION_ASSIGNMENT,
                                                        COERCE_IMPLICIT_CAST,
                                                        -1);
      if (transform == NULL)
            ereport(ERROR,
                        (errcode(ERRCODE_DATATYPE_MISMATCH),
                         errmsg("column \"%s\" cannot be cast to type %s",
                                    colName, format_type_be(targettype))));

      /*
       * Add a work queue item to make ATRewriteTable update the column
       * contents.
       */
      newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
      newval->attnum = attnum;
      newval->expr = (Expr *) transform;

      tab->newvals = lappend(tab->newvals, newval);

      ReleaseSysCache(tuple);

      /*
       * The recursion case is handled by ATSimpleRecursion.      However, if we are
       * told not to recurse, there had better not be any child tables; else the
       * alter would put them out of step.
       */
      if (recurse)
            ATSimpleRecursion(wqueue, rel, cmd, recurse);
      else if (!recursing &&
                   find_inheritance_children(RelationGetRelid(rel), NoLock) != NIL)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                         errmsg("type of inherited column \"%s\" must be changed in child tables too",
                                    colName)));
}

static void
ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
                                const char *colName, TypeName *typename)
{
      HeapTuple   heapTup;
      Form_pg_attribute attTup;
      AttrNumber  attnum;
      HeapTuple   typeTuple;
      Form_pg_type tform;
      Oid               targettype;
      int32       targettypmod;
      Node     *defaultexpr;
      Relation    attrelation;
      Relation    depRel;
      ScanKeyData key[3];
      SysScanDesc scan;
      HeapTuple   depTup;

      attrelation = heap_open(AttributeRelationId, RowExclusiveLock);

      /* Look up the target column */
      heapTup = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
      if (!HeapTupleIsValid(heapTup))           /* shouldn't happen */
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_COLUMN),
                         errmsg("column \"%s\" of relation \"%s\" does not exist",
                                    colName, RelationGetRelationName(rel))));
      attTup = (Form_pg_attribute) GETSTRUCT(heapTup);
      attnum = attTup->attnum;

      /* Check for multiple ALTER TYPE on same column --- can't cope */
      if (attTup->atttypid != tab->oldDesc->attrs[attnum - 1]->atttypid ||
            attTup->atttypmod != tab->oldDesc->attrs[attnum - 1]->atttypmod)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot alter type of column \"%s\" twice",
                                    colName)));

      /* Look up the target type (should not fail, since prep found it) */
      typeTuple = typenameType(NULL, typename, &targettypmod);
      tform = (Form_pg_type) GETSTRUCT(typeTuple);
      targettype = HeapTupleGetOid(typeTuple);

      /*
       * If there is a default expression for the column, get it and ensure we
       * can coerce it to the new datatype.  (We must do this before changing
       * the column type, because build_column_default itself will try to
       * coerce, and will not issue the error message we want if it fails.)
       *
       * We remove any implicit coercion steps at the top level of the old
       * default expression; this has been agreed to satisfy the principle of
       * least surprise.      (The conversion to the new column type should act like
       * it started from what the user sees as the stored expression, and the
       * implicit coercions aren't going to be shown.)
       */
      if (attTup->atthasdef)
      {
            defaultexpr = build_column_default(rel, attnum);
            Assert(defaultexpr);
            defaultexpr = strip_implicit_coercions(defaultexpr);
            defaultexpr = coerce_to_target_type(NULL,       /* no UNKNOWN params */
                                                              defaultexpr, exprType(defaultexpr),
                                                                  targettype, targettypmod,
                                                                  COERCION_ASSIGNMENT,
                                                                  COERCE_IMPLICIT_CAST,
                                                                  -1);
            if (defaultexpr == NULL)
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                        errmsg("default for column \"%s\" cannot be cast to type %s",
                                 colName, format_type_be(targettype))));
      }
      else
            defaultexpr = NULL;

      /*
       * Find everything that depends on the column (constraints, indexes, etc),
       * and record enough information to let us recreate the objects.
       *
       * The actual recreation does not happen here, but only after we have
       * performed all the individual ALTER TYPE operations.      We have to save
       * the info before executing ALTER TYPE, though, else the deparser will
       * get confused.
       *
       * There could be multiple entries for the same object, so we must check
       * to ensure we process each one only once.  Note: we assume that an index
       * that implements a constraint will not show a direct dependency on the
       * column.
       */
      depRel = heap_open(DependRelationId, RowExclusiveLock);

      ScanKeyInit(&key[0],
                        Anum_pg_depend_refclassid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_refobjid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      ScanKeyInit(&key[2],
                        Anum_pg_depend_refobjsubid,
                        BTEqualStrategyNumber, F_INT4EQ,
                        Int32GetDatum((int32) attnum));

      scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                                            SnapshotNow, 3, key);

      while (HeapTupleIsValid(depTup = systable_getnext(scan)))
      {
            Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);
            ObjectAddress foundObject;

            /* We don't expect any PIN dependencies on columns */
            if (foundDep->deptype == DEPENDENCY_PIN)
                  elog(ERROR, "cannot alter type of a pinned column");

            foundObject.classId = foundDep->classid;
            foundObject.objectId = foundDep->objid;
            foundObject.objectSubId = foundDep->objsubid;

            switch (getObjectClass(&foundObject))
            {
                  case OCLASS_CLASS:
                        {
                              char        relKind = get_rel_relkind(foundObject.objectId);

                              if (relKind == RELKIND_INDEX)
                              {
                                    Assert(foundObject.objectSubId == 0);
                                    if (!list_member_oid(tab->changedIndexOids, foundObject.objectId))
                                    {
                                          tab->changedIndexOids = lappend_oid(tab->changedIndexOids,
                                                                                 foundObject.objectId);
                                          tab->changedIndexDefs = lappend(tab->changedIndexDefs,
                                             pg_get_indexdef_string(foundObject.objectId));
                                    }
                              }
                              else if (relKind == RELKIND_SEQUENCE)
                              {
                                    /*
                                     * This must be a SERIAL column's sequence.  We need
                                     * not do anything to it.
                                     */
                                    Assert(foundObject.objectSubId == 0);
                              }
                              else
                              {
                                    /* Not expecting any other direct dependencies... */
                                    elog(ERROR, "unexpected object depending on column: %s",
                                           getObjectDescription(&foundObject));
                              }
                              break;
                        }

                  case OCLASS_CONSTRAINT:
                        Assert(foundObject.objectSubId == 0);
                        if (!list_member_oid(tab->changedConstraintOids,
                                                       foundObject.objectId))
                        {
                              char     *defstring = pg_get_constraintdef_string(foundObject.objectId);

                              /*
                               * Put NORMAL dependencies at the front of the list and
                               * AUTO dependencies at the back.  This makes sure that
                               * foreign-key constraints depending on this column will
                               * be dropped before unique or primary-key constraints of
                               * the column; which we must have because the FK
                               * constraints depend on the indexes belonging to the
                               * unique constraints.
                               */
                              if (foundDep->deptype == DEPENDENCY_NORMAL)
                              {
                                    tab->changedConstraintOids =
                                          lcons_oid(foundObject.objectId,
                                                        tab->changedConstraintOids);
                                    tab->changedConstraintDefs =
                                          lcons(defstring,
                                                  tab->changedConstraintDefs);
                              }
                              else
                              {
                                    tab->changedConstraintOids =
                                          lappend_oid(tab->changedConstraintOids,
                                                            foundObject.objectId);
                                    tab->changedConstraintDefs =
                                          lappend(tab->changedConstraintDefs,
                                                      defstring);
                              }
                        }
                        break;

                  case OCLASS_REWRITE:
                        /* XXX someday see if we can cope with revising views */
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("cannot alter type of a column used by a view or rule"),
                                     errdetail("%s depends on column \"%s\"",
                                                   getObjectDescription(&foundObject),
                                                   colName)));
                        break;

                  case OCLASS_DEFAULT:

                        /*
                         * Ignore the column's default expression, since we will fix
                         * it below.
                         */
                        Assert(defaultexpr);
                        break;

                  case OCLASS_PROC:
                  case OCLASS_TYPE:
                  case OCLASS_CAST:
                  case OCLASS_CONVERSION:
                  case OCLASS_LANGUAGE:
                  case OCLASS_OPERATOR:
                  case OCLASS_OPCLASS:
                  case OCLASS_OPFAMILY:
                  case OCLASS_TRIGGER:
                  case OCLASS_SCHEMA:
                  case OCLASS_TSPARSER:
                  case OCLASS_TSDICT:
                  case OCLASS_TSTEMPLATE:
                  case OCLASS_TSCONFIG:

                        /*
                         * We don't expect any of these sorts of objects to depend on
                         * a column.
                         */
                        elog(ERROR, "unexpected object depending on column: %s",
                               getObjectDescription(&foundObject));
                        break;

                  default:
                        elog(ERROR, "unrecognized object class: %u",
                               foundObject.classId);
            }
      }

      systable_endscan(scan);

      /*
       * Now scan for dependencies of this column on other things.  The only
       * thing we should find is the dependency on the column datatype, which we
       * want to remove.
       */
      ScanKeyInit(&key[0],
                        Anum_pg_depend_classid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_objid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      ScanKeyInit(&key[2],
                        Anum_pg_depend_objsubid,
                        BTEqualStrategyNumber, F_INT4EQ,
                        Int32GetDatum((int32) attnum));

      scan = systable_beginscan(depRel, DependDependerIndexId, true,
                                            SnapshotNow, 3, key);

      while (HeapTupleIsValid(depTup = systable_getnext(scan)))
      {
            Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(depTup);

            if (foundDep->deptype != DEPENDENCY_NORMAL)
                  elog(ERROR, "found unexpected dependency type '%c'",
                         foundDep->deptype);
            if (foundDep->refclassid != TypeRelationId ||
                  foundDep->refobjid != attTup->atttypid)
                  elog(ERROR, "found unexpected dependency for column");

            simple_heap_delete(depRel, &depTup->t_self);
      }

      systable_endscan(scan);

      heap_close(depRel, RowExclusiveLock);

      /*
       * Here we go --- change the recorded column type.    (Note heapTup is a
       * copy of the syscache entry, so okay to scribble on.)
       */
      attTup->atttypid = targettype;
      attTup->atttypmod = targettypmod;
      attTup->attndims = list_length(typename->arrayBounds);
      attTup->attlen = tform->typlen;
      attTup->attbyval = tform->typbyval;
      attTup->attalign = tform->typalign;
      attTup->attstorage = tform->typstorage;

      ReleaseSysCache(typeTuple);

      simple_heap_update(attrelation, &heapTup->t_self, heapTup);

      /* keep system catalog indexes current */
      CatalogUpdateIndexes(attrelation, heapTup);

      heap_close(attrelation, RowExclusiveLock);

      /* Install dependency on new datatype */
      add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype);

      /*
       * Drop any pg_statistic entry for the column, since it's now wrong type
       */
      RemoveStatistics(RelationGetRelid(rel), attnum);

      /*
       * Update the default, if present, by brute force --- remove and re-add
       * the default.  Probably unsafe to take shortcuts, since the new version
       * may well have additional dependencies.  (It's okay to do this now,
       * rather than after other ALTER TYPE commands, since the default won't
       * depend on other column types.)
       */
      if (defaultexpr)
      {
            /* Must make new row visible since it will be updated again */
            CommandCounterIncrement();

            /*
             * We use RESTRICT here for safety, but at present we do not expect
             * anything to depend on the default.
             */
            RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true);

            StoreAttrDefault(rel, attnum, defaultexpr);
      }

      /* Cleanup */
      heap_freetuple(heapTup);
}

/*
 * Cleanup after we've finished all the ALTER TYPE operations for a
 * particular relation.  We have to drop and recreate all the indexes
 * and constraints that depend on the altered columns.
 */
static void
ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab)
{
      ObjectAddress obj;
      ListCell   *l;

      /*
       * Re-parse the index and constraint definitions, and attach them to the
       * appropriate work queue entries.  We do this before dropping because in
       * the case of a FOREIGN KEY constraint, we might not yet have exclusive
       * lock on the table the constraint is attached to, and we need to get
       * that before dropping.  It's safe because the parser won't actually look
       * at the catalogs to detect the existing entry.
       */
      foreach(l, tab->changedIndexDefs)
            ATPostAlterTypeParse((char *) lfirst(l), wqueue);
      foreach(l, tab->changedConstraintDefs)
            ATPostAlterTypeParse((char *) lfirst(l), wqueue);

      /*
       * Now we can drop the existing constraints and indexes --- constraints
       * first, since some of them might depend on the indexes.  In fact, we
       * have to delete FOREIGN KEY constraints before UNIQUE constraints, but
       * we already ordered the constraint list to ensure that would happen. It
       * should be okay to use DROP_RESTRICT here, since nothing else should be
       * depending on these objects.
       */
      foreach(l, tab->changedConstraintOids)
      {
            obj.classId = ConstraintRelationId;
            obj.objectId = lfirst_oid(l);
            obj.objectSubId = 0;
            performDeletion(&obj, DROP_RESTRICT);
      }

      foreach(l, tab->changedIndexOids)
      {
            obj.classId = RelationRelationId;
            obj.objectId = lfirst_oid(l);
            obj.objectSubId = 0;
            performDeletion(&obj, DROP_RESTRICT);
      }

      /*
       * The objects will get recreated during subsequent passes over the work
       * queue.
       */
}

static void
ATPostAlterTypeParse(char *cmd, List **wqueue)
{
      List     *raw_parsetree_list;
      List     *querytree_list;
      ListCell   *list_item;

      /*
       * We expect that we will get only ALTER TABLE and CREATE INDEX
       * statements. Hence, there is no need to pass them through
       * parse_analyze() or the rewriter, but instead we need to pass them
       * through parse_utilcmd.c to make them ready for execution.
       */
      raw_parsetree_list = raw_parser(cmd);
      querytree_list = NIL;
      foreach(list_item, raw_parsetree_list)
      {
            Node     *stmt = (Node *) lfirst(list_item);

            if (IsA(stmt, IndexStmt))
                  querytree_list = lappend(querytree_list,
                                                       transformIndexStmt((IndexStmt *) stmt,
                                                                                    cmd));
            else if (IsA(stmt, AlterTableStmt))
                  querytree_list = list_concat(querytree_list,
                                           transformAlterTableStmt((AlterTableStmt *) stmt,
                                                                               cmd));
            else
                  querytree_list = lappend(querytree_list, stmt);
      }

      /*
       * Attach each generated command to the proper place in the work queue.
       * Note this could result in creation of entirely new work-queue entries.
       */
      foreach(list_item, querytree_list)
      {
            Node     *stm = (Node *) lfirst(list_item);
            Relation    rel;
            AlteredTableInfo *tab;

            switch (nodeTag(stm))
            {
                  case T_IndexStmt:
                        {
                              IndexStmt  *stmt = (IndexStmt *) stm;
                              AlterTableCmd *newcmd;

                              rel = relation_openrv(stmt->relation, AccessExclusiveLock);
                              tab = ATGetQueueEntry(wqueue, rel);
                              newcmd = makeNode(AlterTableCmd);
                              newcmd->subtype = AT_ReAddIndex;
                              newcmd->def = (Node *) stmt;
                              tab->subcmds[AT_PASS_OLD_INDEX] =
                                    lappend(tab->subcmds[AT_PASS_OLD_INDEX], newcmd);
                              relation_close(rel, NoLock);
                              break;
                        }
                  case T_AlterTableStmt:
                        {
                              AlterTableStmt *stmt = (AlterTableStmt *) stm;
                              ListCell   *lcmd;

                              rel = relation_openrv(stmt->relation, AccessExclusiveLock);
                              tab = ATGetQueueEntry(wqueue, rel);
                              foreach(lcmd, stmt->cmds)
                              {
                                    AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

                                    switch (cmd->subtype)
                                    {
                                          case AT_AddIndex:
                                                cmd->subtype = AT_ReAddIndex;
                                                tab->subcmds[AT_PASS_OLD_INDEX] =
                                                      lappend(tab->subcmds[AT_PASS_OLD_INDEX], cmd);
                                                break;
                                          case AT_AddConstraint:
                                                tab->subcmds[AT_PASS_OLD_CONSTR] =
                                                      lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd);
                                                break;
                                          default:
                                                elog(ERROR, "unexpected statement type: %d",
                                                       (int) cmd->subtype);
                                    }
                              }
                              relation_close(rel, NoLock);
                              break;
                        }
                  default:
                        elog(ERROR, "unexpected statement type: %d",
                               (int) nodeTag(stm));
            }
      }
}


/*
 * ALTER TABLE OWNER
 *
 * recursing is true if we are recursing from a table to its indexes,
 * sequences, or toast table.  We don't allow the ownership of those things to
 * be changed separately from the parent table.  Also, we can skip permission
 * checks (this is necessary not just an optimization, else we'd fail to
 * handle toast tables properly).
 *
 * recursing is also true if ALTER TYPE OWNER is calling us to fix up a
 * free-standing composite type.
 */
void
ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing)
{
      Relation    target_rel;
      Relation    class_rel;
      HeapTuple   tuple;
      Form_pg_class tuple_class;

      /*
       * Get exclusive lock till end of transaction on the target table. Use
       * relation_open so that we can work on indexes and sequences.
       */
      target_rel = relation_open(relationOid, AccessExclusiveLock);

      /* Get its pg_class tuple, too */
      class_rel = heap_open(RelationRelationId, RowExclusiveLock);

      tuple = SearchSysCache(RELOID,
                                       ObjectIdGetDatum(relationOid),
                                       0, 0, 0);
      if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", relationOid);
      tuple_class = (Form_pg_class) GETSTRUCT(tuple);

      /* Can we change the ownership of this tuple? */
      switch (tuple_class->relkind)
      {
            case RELKIND_RELATION:
            case RELKIND_VIEW:
                  /* ok to change owner */
                  break;
            case RELKIND_INDEX:
                  if (!recursing)
                  {
                        /*
                         * Because ALTER INDEX OWNER used to be allowed, and in fact
                         * is generated by old versions of pg_dump, we give a warning
                         * and do nothing rather than erroring out.  Also, to avoid
                         * unnecessary chatter while restoring those old dumps, say
                         * nothing at all if the command would be a no-op anyway.
                         */
                        if (tuple_class->relowner != newOwnerId)
                              ereport(WARNING,
                                          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                           errmsg("cannot change owner of index \"%s\"",
                                                      NameStr(tuple_class->relname)),
                                           errhint("Change the ownership of the index's table, instead.")));
                        /* quick hack to exit via the no-op path */
                        newOwnerId = tuple_class->relowner;
                  }
                  break;
            case RELKIND_SEQUENCE:
                  if (!recursing &&
                        tuple_class->relowner != newOwnerId)
                  {
                        /* if it's an owned sequence, disallow changing it by itself */
                        Oid               tableId;
                        int32       colId;

                        if (sequenceIsOwned(relationOid, &tableId, &colId))
                              ereport(ERROR,
                                          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                           errmsg("cannot change owner of sequence \"%s\"",
                                                      NameStr(tuple_class->relname)),
                                errdetail("Sequence \"%s\" is linked to table \"%s\".",
                                                NameStr(tuple_class->relname),
                                                get_rel_name(tableId))));
                  }
                  break;
            case RELKIND_COMPOSITE_TYPE:
                  if (recursing)
                        break;
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is a composite type",
                                          NameStr(tuple_class->relname)),
                               errhint("Use ALTER TYPE instead.")));
                  break;
            case RELKIND_TOASTVALUE:
                  if (recursing)
                        break;
                  /* FALL THRU */
            default:
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is not a table, view, or sequence",
                                          NameStr(tuple_class->relname))));
      }

      /*
       * If the new owner is the same as the existing owner, consider the
       * command to have succeeded.  This is for dump restoration purposes.
       */
      if (tuple_class->relowner != newOwnerId)
      {
            Datum       repl_val[Natts_pg_class];
            bool        repl_null[Natts_pg_class];
            bool        repl_repl[Natts_pg_class];
            Acl            *newAcl;
            Datum       aclDatum;
            bool        isNull;
            HeapTuple   newtuple;

            /* skip permission checks when recursing to index or toast table */
            if (!recursing)
            {
                  /* Superusers can always do it */
                  if (!superuser())
                  {
                        Oid               namespaceOid = tuple_class->relnamespace;
                        AclResult   aclresult;

                        /* Otherwise, must be owner of the existing object */
                        if (!pg_class_ownercheck(relationOid, GetUserId()))
                              aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                                   RelationGetRelationName(target_rel));

                        /* Must be able to become new owner */
                        check_is_member_of_role(GetUserId(), newOwnerId);

                        /* New owner must have CREATE privilege on namespace */
                        aclresult = pg_namespace_aclcheck(namespaceOid, newOwnerId,
                                                                          ACL_CREATE);
                        if (aclresult != ACLCHECK_OK)
                              aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
                                                   get_namespace_name(namespaceOid));
                  }
            }

            memset(repl_null, false, sizeof(repl_null));
            memset(repl_repl, false, sizeof(repl_repl));

            repl_repl[Anum_pg_class_relowner - 1] = true;
            repl_val[Anum_pg_class_relowner - 1] = ObjectIdGetDatum(newOwnerId);

            /*
             * Determine the modified ACL for the new owner.  This is only
             * necessary when the ACL is non-null.
             */
            aclDatum = SysCacheGetAttr(RELOID, tuple,
                                                   Anum_pg_class_relacl,
                                                   &isNull);
            if (!isNull)
            {
                  newAcl = aclnewowner(DatumGetAclP(aclDatum),
                                                 tuple_class->relowner, newOwnerId);
                  repl_repl[Anum_pg_class_relacl - 1] = true;
                  repl_val[Anum_pg_class_relacl - 1] = PointerGetDatum(newAcl);
            }

            newtuple = heap_modify_tuple(tuple, RelationGetDescr(class_rel), repl_val, repl_null, repl_repl);

            simple_heap_update(class_rel, &newtuple->t_self, newtuple);
            CatalogUpdateIndexes(class_rel, newtuple);

            heap_freetuple(newtuple);

            /*
             * Update owner dependency reference, if any.  A composite type has
             * none, because it's tracked for the pg_type entry instead of here;
             * indexes and TOAST tables don't have their own entries either.
             */
            if (tuple_class->relkind != RELKIND_COMPOSITE_TYPE &&
                  tuple_class->relkind != RELKIND_INDEX &&
                  tuple_class->relkind != RELKIND_TOASTVALUE)
                  changeDependencyOnOwner(RelationRelationId, relationOid,
                                                      newOwnerId);

            /*
             * Also change the ownership of the table's rowtype, if it has one
             */
            if (tuple_class->relkind != RELKIND_INDEX)
                  AlterTypeOwnerInternal(tuple_class->reltype, newOwnerId,
                                           tuple_class->relkind == RELKIND_COMPOSITE_TYPE);

            /*
             * If we are operating on a table, also change the ownership of any
             * indexes and sequences that belong to the table, as well as the
             * table's toast table (if it has one)
             */
            if (tuple_class->relkind == RELKIND_RELATION ||
                  tuple_class->relkind == RELKIND_TOASTVALUE)
            {
                  List     *index_oid_list;
                  ListCell   *i;

                  /* Find all the indexes belonging to this relation */
                  index_oid_list = RelationGetIndexList(target_rel);

                  /* For each index, recursively change its ownership */
                  foreach(i, index_oid_list)
                        ATExecChangeOwner(lfirst_oid(i), newOwnerId, true);

                  list_free(index_oid_list);
            }

            if (tuple_class->relkind == RELKIND_RELATION)
            {
                  /* If it has a toast table, recurse to change its ownership */
                  if (tuple_class->reltoastrelid != InvalidOid)
                        ATExecChangeOwner(tuple_class->reltoastrelid, newOwnerId,
                                                  true);

                  /* If it has dependent sequences, recurse to change them too */
                  change_owner_recurse_to_sequences(relationOid, newOwnerId);
            }
      }

      ReleaseSysCache(tuple);
      heap_close(class_rel, RowExclusiveLock);
      relation_close(target_rel, NoLock);
}

/*
 * change_owner_recurse_to_sequences
 *
 * Helper function for ATExecChangeOwner.  Examines pg_depend searching
 * for sequences that are dependent on serial columns, and changes their
 * ownership.
 */
static void
change_owner_recurse_to_sequences(Oid relationOid, Oid newOwnerId)
{
      Relation    depRel;
      SysScanDesc scan;
      ScanKeyData key[2];
      HeapTuple   tup;

      /*
       * SERIAL sequences are those having an auto dependency on one of the
       * table's columns (we don't care *which* column, exactly).
       */
      depRel = heap_open(DependRelationId, AccessShareLock);

      ScanKeyInit(&key[0],
                        Anum_pg_depend_refclassid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_refobjid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(relationOid));
      /* we leave refobjsubid unspecified */

      scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                                            SnapshotNow, 2, key);

      while (HeapTupleIsValid(tup = systable_getnext(scan)))
      {
            Form_pg_depend depForm = (Form_pg_depend) GETSTRUCT(tup);
            Relation    seqRel;

            /* skip dependencies other than auto dependencies on columns */
            if (depForm->refobjsubid == 0 ||
                  depForm->classid != RelationRelationId ||
                  depForm->objsubid != 0 ||
                  depForm->deptype != DEPENDENCY_AUTO)
                  continue;

            /* Use relation_open just in case it's an index */
            seqRel = relation_open(depForm->objid, AccessExclusiveLock);

            /* skip non-sequence relations */
            if (RelationGetForm(seqRel)->relkind != RELKIND_SEQUENCE)
            {
                  /* No need to keep the lock */
                  relation_close(seqRel, AccessExclusiveLock);
                  continue;
            }

            /* We don't need to close the sequence while we alter it. */
            ATExecChangeOwner(depForm->objid, newOwnerId, true);

            /* Now we can close it.  Keep the lock till end of transaction. */
            relation_close(seqRel, NoLock);
      }

      systable_endscan(scan);

      relation_close(depRel, AccessShareLock);
}

/*
 * ALTER TABLE CLUSTER ON
 *
 * The only thing we have to do is to change the indisclustered bits.
 */
static void
ATExecClusterOn(Relation rel, const char *indexName)
{
      Oid               indexOid;

      indexOid = get_relname_relid(indexName, rel->rd_rel->relnamespace);

      if (!OidIsValid(indexOid))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("index \"%s\" for table \"%s\" does not exist",
                                    indexName, RelationGetRelationName(rel))));

      /* Check index is valid to cluster on */
      check_index_is_clusterable(rel, indexOid, false);

      /* And do the work */
      mark_index_clustered(rel, indexOid);
}

/*
 * ALTER TABLE SET WITHOUT CLUSTER
 *
 * We have to find any indexes on the table that have indisclustered bit
 * set and turn it off.
 */
static void
ATExecDropCluster(Relation rel)
{
      mark_index_clustered(rel, InvalidOid);
}

/*
 * ALTER TABLE SET TABLESPACE
 */
static void
ATPrepSetTableSpace(AlteredTableInfo *tab, Relation rel, char *tablespacename)
{
      Oid               tablespaceId;
      AclResult   aclresult;

      /* Check that the tablespace exists */
      tablespaceId = get_tablespace_oid(tablespacename);
      if (!OidIsValid(tablespaceId))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("tablespace \"%s\" does not exist", tablespacename)));

      /* Check its permissions */
      aclresult = pg_tablespace_aclcheck(tablespaceId, GetUserId(), ACL_CREATE);
      if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_TABLESPACE, tablespacename);

      /* Save info for Phase 3 to do the real work */
      if (OidIsValid(tab->newTableSpace))
            ereport(ERROR,
                        (errcode(ERRCODE_SYNTAX_ERROR),
                         errmsg("cannot have multiple SET TABLESPACE subcommands")));
      tab->newTableSpace = tablespaceId;
}

/*
 * ALTER TABLE/INDEX SET (...) or RESET (...)
 */
static void
ATExecSetRelOptions(Relation rel, List *defList, bool isReset)
{
      Oid               relid;
      Relation    pgclass;
      HeapTuple   tuple;
      HeapTuple   newtuple;
      Datum       datum;
      bool        isnull;
      Datum       newOptions;
      Datum       repl_val[Natts_pg_class];
      bool        repl_null[Natts_pg_class];
      bool        repl_repl[Natts_pg_class];
      static char *validnsps[] = HEAP_RELOPT_NAMESPACES;

      if (defList == NIL)
            return;                             /* nothing to do */

      pgclass = heap_open(RelationRelationId, RowExclusiveLock);

      /* Get the old reloptions */
      relid = RelationGetRelid(rel);
      tuple = SearchSysCache(RELOID,
                                       ObjectIdGetDatum(relid),
                                       0, 0, 0);
      if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", relid);

      datum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_reloptions, &isnull);

      /* Generate new proposed reloptions (text array) */
      newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
                                                   defList, NULL, validnsps, false, isReset);

      /* Validate */
      switch (rel->rd_rel->relkind)
      {
            case RELKIND_RELATION:
            case RELKIND_TOASTVALUE:
                  (void) heap_reloptions(rel->rd_rel->relkind, newOptions, true);
                  break;
            case RELKIND_INDEX:
                  (void) index_reloptions(rel->rd_am->amoptions, newOptions, true);
                  break;
            default:
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is not a table, index, or TOAST table",
                                          RelationGetRelationName(rel))));
                  break;
      }

      /*
       * All we need do here is update the pg_class row; the new options will be
       * propagated into relcaches during post-commit cache inval.
       */
      memset(repl_val, 0, sizeof(repl_val));
      memset(repl_null, false, sizeof(repl_null));
      memset(repl_repl, false, sizeof(repl_repl));

      if (newOptions != (Datum) 0)
            repl_val[Anum_pg_class_reloptions - 1] = newOptions;
      else
            repl_null[Anum_pg_class_reloptions - 1] = true;

      repl_repl[Anum_pg_class_reloptions - 1] = true;

      newtuple = heap_modify_tuple(tuple, RelationGetDescr(pgclass),
                                                 repl_val, repl_null, repl_repl);

      simple_heap_update(pgclass, &newtuple->t_self, newtuple);

      CatalogUpdateIndexes(pgclass, newtuple);

      heap_freetuple(newtuple);

      ReleaseSysCache(tuple);

      /* repeat the whole exercise for the toast table, if there's one */
      if (OidIsValid(rel->rd_rel->reltoastrelid))
      {
            Relation    toastrel;
            Oid               toastid = rel->rd_rel->reltoastrelid;

            toastrel = heap_open(toastid, AccessExclusiveLock);

            /* Get the old reloptions */
            tuple = SearchSysCache(RELOID,
                                             ObjectIdGetDatum(toastid),
                                             0, 0, 0);
            if (!HeapTupleIsValid(tuple))
                  elog(ERROR, "cache lookup failed for relation %u", toastid);

            datum = SysCacheGetAttr(RELOID, tuple, Anum_pg_class_reloptions, &isnull);

            newOptions = transformRelOptions(isnull ? (Datum) 0 : datum,
                                                defList, "toast", validnsps, false, isReset);

            (void) heap_reloptions(RELKIND_TOASTVALUE, newOptions, true);

            memset(repl_val, 0, sizeof(repl_val));
            memset(repl_null, false, sizeof(repl_null));
            memset(repl_repl, false, sizeof(repl_repl));

            if (newOptions != (Datum) 0)
                  repl_val[Anum_pg_class_reloptions - 1] = newOptions;
            else
                  repl_null[Anum_pg_class_reloptions - 1] = true;

            repl_repl[Anum_pg_class_reloptions - 1] = true;

            newtuple = heap_modify_tuple(tuple, RelationGetDescr(pgclass),
                                                       repl_val, repl_null, repl_repl);

            simple_heap_update(pgclass, &newtuple->t_self, newtuple);

            CatalogUpdateIndexes(pgclass, newtuple);

            heap_freetuple(newtuple);

            ReleaseSysCache(tuple);

            heap_close(toastrel, NoLock);
      }

      heap_close(pgclass, RowExclusiveLock);
}

/*
 * Execute ALTER TABLE SET TABLESPACE for cases where there is no tuple
 * rewriting to be done, so we just want to copy the data as fast as possible.
 */
static void
ATExecSetTableSpace(Oid tableOid, Oid newTableSpace)
{
      Relation    rel;
      Oid               oldTableSpace;
      Oid               reltoastrelid;
      Oid               reltoastidxid;
      Oid               newrelfilenode;
      RelFileNode newrnode;
      SMgrRelation dstrel;
      Relation    pg_class;
      HeapTuple   tuple;
      Form_pg_class rd_rel;
      ForkNumber  forkNum;

      /*
       * Need lock here in case we are recursing to toast table or index
       */
      rel = relation_open(tableOid, AccessExclusiveLock);

      /*
       * We can never allow moving of shared or nailed-in-cache relations,
       * because we can't support changing their reltablespace values.
       */
      if (rel->rd_rel->relisshared || rel->rd_isnailed)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot move system relation \"%s\"",
                                    RelationGetRelationName(rel))));

      /* Can't move a non-shared relation into pg_global */
      if (newTableSpace == GLOBALTABLESPACE_OID)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("only shared relations can be placed in pg_global tablespace")));

      /*
       * Don't allow moving temp tables of other backends ... their local buffer
       * manager is not going to cope.
       */
      if (RELATION_IS_OTHER_TEMP(rel))
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot move temporary tables of other sessions")));

      /*
       * No work if no change in tablespace.
       */
      oldTableSpace = rel->rd_rel->reltablespace;
      if (newTableSpace == oldTableSpace ||
            (newTableSpace == MyDatabaseTableSpace && oldTableSpace == 0))
      {
            relation_close(rel, NoLock);
            return;
      }

      reltoastrelid = rel->rd_rel->reltoastrelid;
      reltoastidxid = rel->rd_rel->reltoastidxid;

      /* Get a modifiable copy of the relation's pg_class row */
      pg_class = heap_open(RelationRelationId, RowExclusiveLock);

      tuple = SearchSysCacheCopy(RELOID,
                                             ObjectIdGetDatum(tableOid),
                                             0, 0, 0);
      if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for relation %u", tableOid);
      rd_rel = (Form_pg_class) GETSTRUCT(tuple);

      /*
       * Since we copy the file directly without looking at the shared buffers,
       * we'd better first flush out any pages of the source relation that are
       * in shared buffers.  We assume no new changes will be made while we are
       * holding exclusive lock on the rel.
       */
      FlushRelationBuffers(rel);

      /*
       * Relfilenodes are not unique across tablespaces, so we need to allocate
       * a new one in the new tablespace.
       */
      newrelfilenode = GetNewRelFileNode(newTableSpace,
                                                         rel->rd_rel->relisshared,
                                                         NULL);

      /* Open old and new relation */
      newrnode = rel->rd_node;
      newrnode.relNode = newrelfilenode;
      newrnode.spcNode = newTableSpace;
      dstrel = smgropen(newrnode);

      RelationOpenSmgr(rel);

      /*
       * Create and copy all forks of the relation, and schedule unlinking of
       * old physical files.
       *
       * NOTE: any conflict in relfilenode value will be caught in
       * RelationCreateStorage().
       */
      RelationCreateStorage(newrnode, rel->rd_istemp);

      /* copy main fork */
      copy_relation_data(rel->rd_smgr, dstrel, MAIN_FORKNUM, rel->rd_istemp);

      /* copy those extra forks that exist */
      for (forkNum = MAIN_FORKNUM + 1; forkNum <= MAX_FORKNUM; forkNum++)
      {
            if (smgrexists(rel->rd_smgr, forkNum))
            {
                  smgrcreate(dstrel, forkNum, false);
                  copy_relation_data(rel->rd_smgr, dstrel, forkNum, rel->rd_istemp);
            }
      }

      /* drop old relation, and close new one */
      RelationDropStorage(rel);
      smgrclose(dstrel);

      /* update the pg_class row */
      rd_rel->reltablespace = (newTableSpace == MyDatabaseTableSpace) ? InvalidOid : newTableSpace;
      rd_rel->relfilenode = newrelfilenode;
      simple_heap_update(pg_class, &tuple->t_self, tuple);
      CatalogUpdateIndexes(pg_class, tuple);

      heap_freetuple(tuple);

      heap_close(pg_class, RowExclusiveLock);

      relation_close(rel, NoLock);

      /* Make sure the reltablespace change is visible */
      CommandCounterIncrement();

      /* Move associated toast relation and/or index, too */
      if (OidIsValid(reltoastrelid))
            ATExecSetTableSpace(reltoastrelid, newTableSpace);
      if (OidIsValid(reltoastidxid))
            ATExecSetTableSpace(reltoastidxid, newTableSpace);
}

/*
 * Copy data, block by block
 */
static void
copy_relation_data(SMgrRelation src, SMgrRelation dst,
                           ForkNumber forkNum, bool istemp)
{
      bool        use_wal;
      BlockNumber nblocks;
      BlockNumber blkno;
      char        buf[BLCKSZ];
      Page        page = (Page) buf;

      /*
       * We need to log the copied data in WAL iff WAL archiving is enabled AND
       * it's not a temp rel.
       */
      use_wal = XLogArchivingActive() && !istemp;

      nblocks = smgrnblocks(src, forkNum);

      for (blkno = 0; blkno < nblocks; blkno++)
      {
            smgrread(src, forkNum, blkno, buf);

            /* XLOG stuff */
            if (use_wal)
                  log_newpage(&dst->smgr_rnode, forkNum, blkno, page);

            /*
             * Now write the page.  We say isTemp = true even if it's not a temp
             * rel, because there's no need for smgr to schedule an fsync for this
             * write; we'll do it ourselves below.
             */
            smgrextend(dst, forkNum, blkno, buf, true);
      }

      /*
       * If the rel isn't temp, we must fsync it down to disk before it's safe
       * to commit the transaction.  (For a temp rel we don't care since the rel
       * will be uninteresting after a crash anyway.)
       *
       * It's obvious that we must do this when not WAL-logging the copy. It's
       * less obvious that we have to do it even if we did WAL-log the copied
       * pages. The reason is that since we're copying outside shared buffers, a
       * CHECKPOINT occurring during the copy has no way to flush the previously
       * written data to disk (indeed it won't know the new rel even exists).  A
       * crash later on would replay WAL from the checkpoint, therefore it
       * wouldn't replay our earlier WAL entries. If we do not fsync those pages
       * here, they might still not be on disk when the crash occurs.
       */
      if (!istemp)
            smgrimmedsync(dst, forkNum);
}

/*
 * ALTER TABLE ENABLE/DISABLE TRIGGER
 *
 * We just pass this off to trigger.c.
 */
static void
ATExecEnableDisableTrigger(Relation rel, char *trigname,
                                       char fires_when, bool skip_system)
{
      EnableDisableTrigger(rel, trigname, fires_when, skip_system);
}

/*
 * ALTER TABLE ENABLE/DISABLE RULE
 *
 * We just pass this off to rewriteDefine.c.
 */
static void
ATExecEnableDisableRule(Relation rel, char *trigname,
                                    char fires_when)
{
      EnableDisableRule(rel, trigname, fires_when);
}

/*
 * ALTER TABLE INHERIT
 *
 * Add a parent to the child's parents. This verifies that all the columns and
 * check constraints of the parent appear in the child and that they have the
 * same data types and expressions.
 */
static void
ATExecAddInherit(Relation child_rel, RangeVar *parent)
{
      Relation    parent_rel,
                        catalogRelation;
      SysScanDesc scan;
      ScanKeyData key;
      HeapTuple   inheritsTuple;
      int32       inhseqno;
      List     *children;

      /*
       * AccessShareLock on the parent is what's obtained during normal CREATE
       * TABLE ... INHERITS ..., so should be enough here.
       */
      parent_rel = heap_openrv(parent, AccessShareLock);

      /*
       * Must be owner of both parent and child -- child was checked by
       * ATSimplePermissions call in ATPrepCmd
       */
      ATSimplePermissions(parent_rel, false);

      /* Permanent rels cannot inherit from temporary ones */
      if (parent_rel->rd_istemp && !child_rel->rd_istemp)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("cannot inherit from temporary relation \"%s\"",
                                    RelationGetRelationName(parent_rel))));

      /*
       * Check for duplicates in the list of parents, and determine the highest
       * inhseqno already present; we'll use the next one for the new parent.
       * (Note: get RowExclusiveLock because we will write pg_inherits below.)
       *
       * Note: we do not reject the case where the child already inherits from
       * the parent indirectly; CREATE TABLE doesn't reject comparable cases.
       */
      catalogRelation = heap_open(InheritsRelationId, RowExclusiveLock);
      ScanKeyInit(&key,
                        Anum_pg_inherits_inhrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(child_rel)));
      scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
                                            true, SnapshotNow, 1, &key);

      /* inhseqno sequences start at 1 */
      inhseqno = 0;
      while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
      {
            Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inheritsTuple);

            if (inh->inhparent == RelationGetRelid(parent_rel))
                  ereport(ERROR,
                              (errcode(ERRCODE_DUPLICATE_TABLE),
                   errmsg("relation \"%s\" would be inherited from more than once",
                              RelationGetRelationName(parent_rel))));
            if (inh->inhseqno > inhseqno)
                  inhseqno = inh->inhseqno;
      }
      systable_endscan(scan);

      /*
       * Prevent circularity by seeing if proposed parent inherits from child.
       * (In particular, this disallows making a rel inherit from itself.)
       *
       * This is not completely bulletproof because of race conditions: in
       * multi-level inheritance trees, someone else could concurrently be
       * making another inheritance link that closes the loop but does not join
       * either of the rels we have locked.  Preventing that seems to require
       * exclusive locks on the entire inheritance tree, which is a cure worse
       * than the disease.  find_all_inheritors() will cope with circularity
       * anyway, so don't sweat it too much.
       *
       * We use weakest lock we can on child's children, namely AccessShareLock.
       */
      children = find_all_inheritors(RelationGetRelid(child_rel),
                                                   AccessShareLock);

      if (list_member_oid(children, RelationGetRelid(parent_rel)))
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_TABLE),
                         errmsg("circular inheritance not allowed"),
                         errdetail("\"%s\" is already a child of \"%s\".",
                                       parent->relname,
                                       RelationGetRelationName(child_rel))));

      /* If parent has OIDs then child must have OIDs */
      if (parent_rel->rd_rel->relhasoids && !child_rel->rd_rel->relhasoids)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("table \"%s\" without OIDs cannot inherit from table \"%s\" with OIDs",
                                    RelationGetRelationName(child_rel),
                                    RelationGetRelationName(parent_rel))));

      /* Match up the columns and bump attinhcount as needed */
      MergeAttributesIntoExisting(child_rel, parent_rel);

      /* Match up the constraints and bump coninhcount as needed */
      MergeConstraintsIntoExisting(child_rel, parent_rel);

      /*
       * OK, it looks valid.  Make the catalog entries that show inheritance.
       */
      StoreCatalogInheritance1(RelationGetRelid(child_rel),
                                           RelationGetRelid(parent_rel),
                                           inhseqno + 1,
                                           catalogRelation);

      /* Now we're done with pg_inherits */
      heap_close(catalogRelation, RowExclusiveLock);

      /* keep our lock on the parent relation until commit */
      heap_close(parent_rel, NoLock);
}

/*
 * Obtain the source-text form of the constraint expression for a check
 * constraint, given its pg_constraint tuple
 */
static char *
decompile_conbin(HeapTuple contup, TupleDesc tupdesc)
{
      Form_pg_constraint con;
      bool        isnull;
      Datum       attr;
      Datum       expr;

      con = (Form_pg_constraint) GETSTRUCT(contup);
      attr = heap_getattr(contup, Anum_pg_constraint_conbin, tupdesc, &isnull);
      if (isnull)
            elog(ERROR, "null conbin for constraint %u", HeapTupleGetOid(contup));

      expr = DirectFunctionCall2(pg_get_expr, attr,
                                             ObjectIdGetDatum(con->conrelid));
      return TextDatumGetCString(expr);
}

/*
 * Determine whether two check constraints are functionally equivalent
 *
 * The test we apply is to see whether they reverse-compile to the same
 * source string.  This insulates us from issues like whether attributes
 * have the same physical column numbers in parent and child relations.
 */
static bool
constraints_equivalent(HeapTuple a, HeapTuple b, TupleDesc tupleDesc)
{
      Form_pg_constraint acon = (Form_pg_constraint) GETSTRUCT(a);
      Form_pg_constraint bcon = (Form_pg_constraint) GETSTRUCT(b);

      if (acon->condeferrable != bcon->condeferrable ||
            acon->condeferred != bcon->condeferred ||
            strcmp(decompile_conbin(a, tupleDesc),
                     decompile_conbin(b, tupleDesc)) != 0)
            return false;
      else
            return true;
}

/*
 * Check columns in child table match up with columns in parent, and increment
 * their attinhcount.
 *
 * Called by ATExecAddInherit
 *
 * Currently all parent columns must be found in child. Missing columns are an
 * error.  One day we might consider creating new columns like CREATE TABLE
 * does.  However, that is widely unpopular --- in the common use case of
 * partitioned tables it's a foot-gun.
 *
 * The data type must match exactly. If the parent column is NOT NULL then
 * the child must be as well. Defaults are not compared, however.
 */
static void
MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
{
      Relation    attrrel;
      AttrNumber  parent_attno;
      int               parent_natts;
      TupleDesc   tupleDesc;
      TupleConstr *constr;
      HeapTuple   tuple;

      attrrel = heap_open(AttributeRelationId, RowExclusiveLock);

      tupleDesc = RelationGetDescr(parent_rel);
      parent_natts = tupleDesc->natts;
      constr = tupleDesc->constr;

      for (parent_attno = 1; parent_attno <= parent_natts; parent_attno++)
      {
            Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
            char     *attributeName = NameStr(attribute->attname);

            /* Ignore dropped columns in the parent. */
            if (attribute->attisdropped)
                  continue;

            /* Find same column in child (matching on column name). */
            tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel),
                                                              attributeName);
            if (HeapTupleIsValid(tuple))
            {
                  /* Check they are same type and typmod */
                  Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);

                  if (attribute->atttypid != childatt->atttypid ||
                        attribute->atttypmod != childatt->atttypmod)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                                     errmsg("child table \"%s\" has different type for column \"%s\"",
                                                RelationGetRelationName(child_rel),
                                                attributeName)));

                  if (attribute->attnotnull && !childatt->attnotnull)
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                        errmsg("column \"%s\" in child table must be marked NOT NULL",
                                 attributeName)));

                  /*
                   * OK, bump the child column's inheritance count.  (If we fail
                   * later on, this change will just roll back.)
                   */
                  childatt->attinhcount++;
                  simple_heap_update(attrrel, &tuple->t_self, tuple);
                  CatalogUpdateIndexes(attrrel, tuple);
                  heap_freetuple(tuple);
            }
            else
            {
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("child table is missing column \"%s\"",
                                          attributeName)));
            }
      }

      heap_close(attrrel, RowExclusiveLock);
}

/*
 * Check constraints in child table match up with constraints in parent,
 * and increment their coninhcount.
 *
 * Called by ATExecAddInherit
 *
 * Currently all constraints in parent must be present in the child. One day we
 * may consider adding new constraints like CREATE TABLE does. We may also want
 * to allow an optional flag on parent table constraints indicating they are
 * intended to ONLY apply to the master table, not to the children. That would
 * make it possible to ensure no records are mistakenly inserted into the
 * master in partitioned tables rather than the appropriate child.
 *
 * XXX This is O(N^2) which may be an issue with tables with hundreds of
 * constraints. As long as tables have more like 10 constraints it shouldn't be
 * a problem though. Even 100 constraints ought not be the end of the world.
 */
static void
MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
{
      Relation    catalog_relation;
      TupleDesc   tuple_desc;
      SysScanDesc parent_scan;
      ScanKeyData parent_key;
      HeapTuple   parent_tuple;

      catalog_relation = heap_open(ConstraintRelationId, RowExclusiveLock);
      tuple_desc = RelationGetDescr(catalog_relation);

      /* Outer loop scans through the parent's constraint definitions */
      ScanKeyInit(&parent_key,
                        Anum_pg_constraint_conrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(parent_rel)));
      parent_scan = systable_beginscan(catalog_relation, ConstraintRelidIndexId,
                                                       true, SnapshotNow, 1, &parent_key);

      while (HeapTupleIsValid(parent_tuple = systable_getnext(parent_scan)))
      {
            Form_pg_constraint parent_con = (Form_pg_constraint) GETSTRUCT(parent_tuple);
            SysScanDesc child_scan;
            ScanKeyData child_key;
            HeapTuple   child_tuple;
            bool        found = false;

            if (parent_con->contype != CONSTRAINT_CHECK)
                  continue;

            /* Search for a child constraint matching this one */
            ScanKeyInit(&child_key,
                              Anum_pg_constraint_conrelid,
                              BTEqualStrategyNumber, F_OIDEQ,
                              ObjectIdGetDatum(RelationGetRelid(child_rel)));
            child_scan = systable_beginscan(catalog_relation, ConstraintRelidIndexId,
                                                            true, SnapshotNow, 1, &child_key);

            while (HeapTupleIsValid(child_tuple = systable_getnext(child_scan)))
            {
                  Form_pg_constraint child_con = (Form_pg_constraint) GETSTRUCT(child_tuple);
                  HeapTuple   child_copy;

                  if (child_con->contype != CONSTRAINT_CHECK)
                        continue;

                  if (strcmp(NameStr(parent_con->conname),
                                 NameStr(child_con->conname)) != 0)
                        continue;

                  if (!constraints_equivalent(parent_tuple, child_tuple, tuple_desc))
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                                     errmsg("child table \"%s\" has different definition for check constraint \"%s\"",
                                                RelationGetRelationName(child_rel),
                                                NameStr(parent_con->conname))));

                  /*
                   * OK, bump the child constraint's inheritance count.  (If we fail
                   * later on, this change will just roll back.)
                   */
                  child_copy = heap_copytuple(child_tuple);
                  child_con = (Form_pg_constraint) GETSTRUCT(child_copy);
                  child_con->coninhcount++;
                  simple_heap_update(catalog_relation, &child_copy->t_self, child_copy);
                  CatalogUpdateIndexes(catalog_relation, child_copy);
                  heap_freetuple(child_copy);

                  found = true;
                  break;
            }

            systable_endscan(child_scan);

            if (!found)
                  ereport(ERROR,
                              (errcode(ERRCODE_DATATYPE_MISMATCH),
                               errmsg("child table is missing constraint \"%s\"",
                                          NameStr(parent_con->conname))));
      }

      systable_endscan(parent_scan);
      heap_close(catalog_relation, RowExclusiveLock);
}

/*
 * ALTER TABLE NO INHERIT
 *
 * Drop a parent from the child's parents. This just adjusts the attinhcount
 * and attislocal of the columns and removes the pg_inherit and pg_depend
 * entries.
 *
 * If attinhcount goes to 0 then attislocal gets set to true. If it goes back
 * up attislocal stays true, which means if a child is ever removed from a
 * parent then its columns will never be automatically dropped which may
 * surprise. But at least we'll never surprise by dropping columns someone
 * isn't expecting to be dropped which would actually mean data loss.
 *
 * coninhcount and conislocal for inherited constraints are adjusted in
 * exactly the same way.
 */
static void
ATExecDropInherit(Relation rel, RangeVar *parent)
{
      Relation    parent_rel;
      Relation    catalogRelation;
      SysScanDesc scan;
      ScanKeyData key[3];
      HeapTuple   inheritsTuple,
                        attributeTuple,
                        constraintTuple,
                        depTuple;
      List     *connames;
      bool        found = false;

      /*
       * AccessShareLock on the parent is probably enough, seeing that DROP
       * TABLE doesn't lock parent tables at all.  We need some lock since we'll
       * be inspecting the parent's schema.
       */
      parent_rel = heap_openrv(parent, AccessShareLock);

      /*
       * We don't bother to check ownership of the parent table --- ownership of
       * the child is presumed enough rights.
       */

      /*
       * Find and destroy the pg_inherits entry linking the two, or error out if
       * there is none.
       */
      catalogRelation = heap_open(InheritsRelationId, RowExclusiveLock);
      ScanKeyInit(&key[0],
                        Anum_pg_inherits_inhrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId,
                                            true, SnapshotNow, 1, key);

      while (HeapTupleIsValid(inheritsTuple = systable_getnext(scan)))
      {
            Oid               inhparent;

            inhparent = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhparent;
            if (inhparent == RelationGetRelid(parent_rel))
            {
                  simple_heap_delete(catalogRelation, &inheritsTuple->t_self);
                  found = true;
                  break;
            }
      }

      systable_endscan(scan);
      heap_close(catalogRelation, RowExclusiveLock);

      if (!found)
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_TABLE),
                         errmsg("relation \"%s\" is not a parent of relation \"%s\"",
                                    RelationGetRelationName(parent_rel),
                                    RelationGetRelationName(rel))));

      /*
       * Search through child columns looking for ones matching parent rel
       */
      catalogRelation = heap_open(AttributeRelationId, RowExclusiveLock);
      ScanKeyInit(&key[0],
                        Anum_pg_attribute_attrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      scan = systable_beginscan(catalogRelation, AttributeRelidNumIndexId,
                                            true, SnapshotNow, 1, key);
      while (HeapTupleIsValid(attributeTuple = systable_getnext(scan)))
      {
            Form_pg_attribute att = (Form_pg_attribute) GETSTRUCT(attributeTuple);

            /* Ignore if dropped or not inherited */
            if (att->attisdropped)
                  continue;
            if (att->attinhcount <= 0)
                  continue;

            if (SearchSysCacheExistsAttName(RelationGetRelid(parent_rel),
                                                            NameStr(att->attname)))
            {
                  /* Decrement inhcount and possibly set islocal to true */
                  HeapTuple   copyTuple = heap_copytuple(attributeTuple);
                  Form_pg_attribute copy_att = (Form_pg_attribute) GETSTRUCT(copyTuple);

                  copy_att->attinhcount--;
                  if (copy_att->attinhcount == 0)
                        copy_att->attislocal = true;

                  simple_heap_update(catalogRelation, &copyTuple->t_self, copyTuple);
                  CatalogUpdateIndexes(catalogRelation, copyTuple);
                  heap_freetuple(copyTuple);
            }
      }
      systable_endscan(scan);
      heap_close(catalogRelation, RowExclusiveLock);

      /*
       * Likewise, find inherited check constraints and disinherit them. To do
       * this, we first need a list of the names of the parent's check
       * constraints.  (We cheat a bit by only checking for name matches,
       * assuming that the expressions will match.)
       */
      catalogRelation = heap_open(ConstraintRelationId, RowExclusiveLock);
      ScanKeyInit(&key[0],
                        Anum_pg_constraint_conrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(parent_rel)));
      scan = systable_beginscan(catalogRelation, ConstraintRelidIndexId,
                                            true, SnapshotNow, 1, key);

      connames = NIL;

      while (HeapTupleIsValid(constraintTuple = systable_getnext(scan)))
      {
            Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(constraintTuple);

            if (con->contype == CONSTRAINT_CHECK)
                  connames = lappend(connames, pstrdup(NameStr(con->conname)));
      }

      systable_endscan(scan);

      /* Now scan the child's constraints */
      ScanKeyInit(&key[0],
                        Anum_pg_constraint_conrelid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      scan = systable_beginscan(catalogRelation, ConstraintRelidIndexId,
                                            true, SnapshotNow, 1, key);

      while (HeapTupleIsValid(constraintTuple = systable_getnext(scan)))
      {
            Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(constraintTuple);
            bool        match;
            ListCell   *lc;

            if (con->contype != CONSTRAINT_CHECK)
                  continue;

            match = false;
            foreach(lc, connames)
            {
                  if (strcmp(NameStr(con->conname), (char *) lfirst(lc)) == 0)
                  {
                        match = true;
                        break;
                  }
            }

            if (match)
            {
                  /* Decrement inhcount and possibly set islocal to true */
                  HeapTuple   copyTuple = heap_copytuple(constraintTuple);
                  Form_pg_constraint copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);

                  if (copy_con->coninhcount <= 0)           /* shouldn't happen */
                        elog(ERROR, "relation %u has non-inherited constraint \"%s\"",
                               RelationGetRelid(rel), NameStr(copy_con->conname));

                  copy_con->coninhcount--;
                  if (copy_con->coninhcount == 0)
                        copy_con->conislocal = true;

                  simple_heap_update(catalogRelation, &copyTuple->t_self, copyTuple);
                  CatalogUpdateIndexes(catalogRelation, copyTuple);
                  heap_freetuple(copyTuple);
            }
      }

      systable_endscan(scan);
      heap_close(catalogRelation, RowExclusiveLock);

      /*
       * Drop the dependency
       *
       * There's no convenient way to do this, so go trawling through pg_depend
       */
      catalogRelation = heap_open(DependRelationId, RowExclusiveLock);

      ScanKeyInit(&key[0],
                        Anum_pg_depend_classid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_objid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      ScanKeyInit(&key[2],
                        Anum_pg_depend_objsubid,
                        BTEqualStrategyNumber, F_INT4EQ,
                        Int32GetDatum(0));

      scan = systable_beginscan(catalogRelation, DependDependerIndexId, true,
                                            SnapshotNow, 3, key);

      while (HeapTupleIsValid(depTuple = systable_getnext(scan)))
      {
            Form_pg_depend dep = (Form_pg_depend) GETSTRUCT(depTuple);

            if (dep->refclassid == RelationRelationId &&
                  dep->refobjid == RelationGetRelid(parent_rel) &&
                  dep->refobjsubid == 0 &&
                  dep->deptype == DEPENDENCY_NORMAL)
                  simple_heap_delete(catalogRelation, &depTuple->t_self);
      }

      systable_endscan(scan);
      heap_close(catalogRelation, RowExclusiveLock);

      /* keep our lock on the parent relation until commit */
      heap_close(parent_rel, NoLock);
}


/*
 * Execute ALTER TABLE SET SCHEMA
 *
 * Note: caller must have checked ownership of the relation already
 */
void
AlterTableNamespace(RangeVar *relation, const char *newschema,
                              ObjectType stmttype)
{
      Relation    rel;
      Oid               relid;
      Oid               oldNspOid;
      Oid               nspOid;
      Relation    classRel;

      rel = relation_openrv(relation, AccessExclusiveLock);

      relid = RelationGetRelid(rel);
      oldNspOid = RelationGetNamespace(rel);

      /* Check relation type against type specified in the ALTER command */
      switch (stmttype)
      {
            case OBJECT_TABLE:

                  /*
                   * For mostly-historical reasons, we allow ALTER TABLE to apply to
                   * all relation types.
                   */
                  break;

            case OBJECT_SEQUENCE:
                  if (rel->rd_rel->relkind != RELKIND_SEQUENCE)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not a sequence",
                                                RelationGetRelationName(rel))));
                  break;

            case OBJECT_VIEW:
                  if (rel->rd_rel->relkind != RELKIND_VIEW)
                        ereport(ERROR,
                                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                     errmsg("\"%s\" is not a view",
                                                RelationGetRelationName(rel))));
                  break;

            default:
                  elog(ERROR, "unrecognized object type: %d", (int) stmttype);
      }

      /* Can we change the schema of this tuple? */
      switch (rel->rd_rel->relkind)
      {
            case RELKIND_RELATION:
            case RELKIND_VIEW:
                  /* ok to change schema */
                  break;
            case RELKIND_SEQUENCE:
                  {
                        /* if it's an owned sequence, disallow moving it by itself */
                        Oid               tableId;
                        int32       colId;

                        if (sequenceIsOwned(relid, &tableId, &colId))
                              ereport(ERROR,
                                          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                           errmsg("cannot move an owned sequence into another schema"),
                                errdetail("Sequence \"%s\" is linked to table \"%s\".",
                                                RelationGetRelationName(rel),
                                                get_rel_name(tableId))));
                  }
                  break;
            case RELKIND_COMPOSITE_TYPE:
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is a composite type",
                                          RelationGetRelationName(rel)),
                               errhint("Use ALTER TYPE instead.")));
                  break;
            case RELKIND_INDEX:
            case RELKIND_TOASTVALUE:
                  /* FALL THRU */
            default:
                  ereport(ERROR,
                              (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                               errmsg("\"%s\" is not a table, view, or sequence",
                                          RelationGetRelationName(rel))));
      }

      /* get schema OID and check its permissions */
      nspOid = LookupCreationNamespace(newschema);

      if (oldNspOid == nspOid)
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_TABLE),
                         errmsg("relation \"%s\" is already in schema \"%s\"",
                                    RelationGetRelationName(rel),
                                    newschema)));

      /* disallow renaming into or out of temp schemas */
      if (isAnyTempNamespace(nspOid) || isAnyTempNamespace(oldNspOid))
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                  errmsg("cannot move objects into or out of temporary schemas")));

      /* same for TOAST schema */
      if (nspOid == PG_TOAST_NAMESPACE || oldNspOid == PG_TOAST_NAMESPACE)
            ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("cannot move objects into or out of TOAST schema")));

      /* OK, modify the pg_class row and pg_depend entry */
      classRel = heap_open(RelationRelationId, RowExclusiveLock);

      AlterRelationNamespaceInternal(classRel, relid, oldNspOid, nspOid, true);

      /* Fix the table's rowtype too */
      AlterTypeNamespaceInternal(rel->rd_rel->reltype, nspOid, false, false);

      /* Fix other dependent stuff */
      if (rel->rd_rel->relkind == RELKIND_RELATION)
      {
            AlterIndexNamespaces(classRel, rel, oldNspOid, nspOid);
            AlterSeqNamespaces(classRel, rel, oldNspOid, nspOid, newschema);
            AlterConstraintNamespaces(relid, oldNspOid, nspOid, false);
      }

      heap_close(classRel, RowExclusiveLock);

      /* close rel, but keep lock until commit */
      relation_close(rel, NoLock);
}

/*
 * The guts of relocating a relation to another namespace: fix the pg_class
 * entry, and the pg_depend entry if any.  Caller must already have
 * opened and write-locked pg_class.
 */
void
AlterRelationNamespaceInternal(Relation classRel, Oid relOid,
                                             Oid oldNspOid, Oid newNspOid,
                                             bool hasDependEntry)
{
      HeapTuple   classTup;
      Form_pg_class classForm;

      classTup = SearchSysCacheCopy(RELOID,
                                                  ObjectIdGetDatum(relOid),
                                                  0, 0, 0);
      if (!HeapTupleIsValid(classTup))
            elog(ERROR, "cache lookup failed for relation %u", relOid);
      classForm = (Form_pg_class) GETSTRUCT(classTup);

      Assert(classForm->relnamespace == oldNspOid);

      /* check for duplicate name (more friendly than unique-index failure) */
      if (get_relname_relid(NameStr(classForm->relname),
                                      newNspOid) != InvalidOid)
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_TABLE),
                         errmsg("relation \"%s\" already exists in schema \"%s\"",
                                    NameStr(classForm->relname),
                                    get_namespace_name(newNspOid))));

      /* classTup is a copy, so OK to scribble on */
      classForm->relnamespace = newNspOid;

      simple_heap_update(classRel, &classTup->t_self, classTup);
      CatalogUpdateIndexes(classRel, classTup);

      /* Update dependency on schema if caller said so */
      if (hasDependEntry &&
            changeDependencyFor(RelationRelationId, relOid,
                                          NamespaceRelationId, oldNspOid, newNspOid) != 1)
            elog(ERROR, "failed to change schema dependency for relation \"%s\"",
                   NameStr(classForm->relname));

      heap_freetuple(classTup);
}

/*
 * Move all indexes for the specified relation to another namespace.
 *
 * Note: we assume adequate permission checking was done by the caller,
 * and that the caller has a suitable lock on the owning relation.
 */
static void
AlterIndexNamespaces(Relation classRel, Relation rel,
                               Oid oldNspOid, Oid newNspOid)
{
      List     *indexList;
      ListCell   *l;

      indexList = RelationGetIndexList(rel);

      foreach(l, indexList)
      {
            Oid               indexOid = lfirst_oid(l);

            /*
             * Note: currently, the index will not have its own dependency on the
             * namespace, so we don't need to do changeDependencyFor(). There's no
             * rowtype in pg_type, either.
             */
            AlterRelationNamespaceInternal(classRel, indexOid,
                                                         oldNspOid, newNspOid,
                                                         false);
      }

      list_free(indexList);
}

/*
 * Move all SERIAL-column sequences of the specified relation to another
 * namespace.
 *
 * Note: we assume adequate permission checking was done by the caller,
 * and that the caller has a suitable lock on the owning relation.
 */
static void
AlterSeqNamespaces(Relation classRel, Relation rel,
                           Oid oldNspOid, Oid newNspOid, const char *newNspName)
{
      Relation    depRel;
      SysScanDesc scan;
      ScanKeyData key[2];
      HeapTuple   tup;

      /*
       * SERIAL sequences are those having an auto dependency on one of the
       * table's columns (we don't care *which* column, exactly).
       */
      depRel = heap_open(DependRelationId, AccessShareLock);

      ScanKeyInit(&key[0],
                        Anum_pg_depend_refclassid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationRelationId));
      ScanKeyInit(&key[1],
                        Anum_pg_depend_refobjid,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(RelationGetRelid(rel)));
      /* we leave refobjsubid unspecified */

      scan = systable_beginscan(depRel, DependReferenceIndexId, true,
                                            SnapshotNow, 2, key);

      while (HeapTupleIsValid(tup = systable_getnext(scan)))
      {
            Form_pg_depend depForm = (Form_pg_depend) GETSTRUCT(tup);
            Relation    seqRel;

            /* skip dependencies other than auto dependencies on columns */
            if (depForm->refobjsubid == 0 ||
                  depForm->classid != RelationRelationId ||
                  depForm->objsubid != 0 ||
                  depForm->deptype != DEPENDENCY_AUTO)
                  continue;

            /* Use relation_open just in case it's an index */
            seqRel = relation_open(depForm->objid, AccessExclusiveLock);

            /* skip non-sequence relations */
            if (RelationGetForm(seqRel)->relkind != RELKIND_SEQUENCE)
            {
                  /* No need to keep the lock */
                  relation_close(seqRel, AccessExclusiveLock);
                  continue;
            }

            /* Fix the pg_class and pg_depend entries */
            AlterRelationNamespaceInternal(classRel, depForm->objid,
                                                         oldNspOid, newNspOid,
                                                         true);

            /*
             * Sequences have entries in pg_type. We need to be careful to move
             * them to the new namespace, too.
             */
            AlterTypeNamespaceInternal(RelationGetForm(seqRel)->reltype,
                                                   newNspOid, false, false);

            /* Now we can close it.  Keep the lock till end of transaction. */
            relation_close(seqRel, NoLock);
      }

      systable_endscan(scan);

      relation_close(depRel, AccessShareLock);
}


/*
 * This code supports
 *    CREATE TEMP TABLE ... ON COMMIT { DROP | PRESERVE ROWS | DELETE ROWS }
 *
 * Because we only support this for TEMP tables, it's sufficient to remember
 * the state in a backend-local data structure.
 */

/*
 * Register a newly-created relation's ON COMMIT action.
 */
void
register_on_commit_action(Oid relid, OnCommitAction action)
{
      OnCommitItem *oc;
      MemoryContext oldcxt;

      /*
       * We needn't bother registering the relation unless there is an ON COMMIT
       * action we need to take.
       */
      if (action == ONCOMMIT_NOOP || action == ONCOMMIT_PRESERVE_ROWS)
            return;

      oldcxt = MemoryContextSwitchTo(CacheMemoryContext);

      oc = (OnCommitItem *) palloc(sizeof(OnCommitItem));
      oc->relid = relid;
      oc->oncommit = action;
      oc->creating_subid = GetCurrentSubTransactionId();
      oc->deleting_subid = InvalidSubTransactionId;

      on_commits = lcons(oc, on_commits);

      MemoryContextSwitchTo(oldcxt);
}

/*
 * Unregister any ON COMMIT action when a relation is deleted.
 *
 * Actually, we only mark the OnCommitItem entry as to be deleted after commit.
 */
void
remove_on_commit_action(Oid relid)
{
      ListCell   *l;

      foreach(l, on_commits)
      {
            OnCommitItem *oc = (OnCommitItem *) lfirst(l);

            if (oc->relid == relid)
            {
                  oc->deleting_subid = GetCurrentSubTransactionId();
                  break;
            }
      }
}

/*
 * Perform ON COMMIT actions.
 *
 * This is invoked just before actually committing, since it's possible
 * to encounter errors.
 */
void
PreCommit_on_commit_actions(void)
{
      ListCell   *l;
      List     *oids_to_truncate = NIL;

      foreach(l, on_commits)
      {
            OnCommitItem *oc = (OnCommitItem *) lfirst(l);

            /* Ignore entry if already dropped in this xact */
            if (oc->deleting_subid != InvalidSubTransactionId)
                  continue;

            switch (oc->oncommit)
            {
                  case ONCOMMIT_NOOP:
                  case ONCOMMIT_PRESERVE_ROWS:
                        /* Do nothing (there shouldn't be such entries, actually) */
                        break;
                  case ONCOMMIT_DELETE_ROWS:
                        oids_to_truncate = lappend_oid(oids_to_truncate, oc->relid);
                        break;
                  case ONCOMMIT_DROP:
                        {
                              ObjectAddress object;

                              object.classId = RelationRelationId;
                              object.objectId = oc->relid;
                              object.objectSubId = 0;
                              performDeletion(&object, DROP_CASCADE);

                              /*
                               * Note that table deletion will call
                               * remove_on_commit_action, so the entry should get marked
                               * as deleted.
                               */
                              Assert(oc->deleting_subid != InvalidSubTransactionId);
                              break;
                        }
            }
      }
      if (oids_to_truncate != NIL)
      {
            heap_truncate(oids_to_truncate);
            CommandCounterIncrement();          /* XXX needed? */
      }
}

/*
 * Post-commit or post-abort cleanup for ON COMMIT management.
 *
 * All we do here is remove no-longer-needed OnCommitItem entries.
 *
 * During commit, remove entries that were deleted during this transaction;
 * during abort, remove those created during this transaction.
 */
void
AtEOXact_on_commit_actions(bool isCommit)
{
      ListCell   *cur_item;
      ListCell   *prev_item;

      prev_item = NULL;
      cur_item = list_head(on_commits);

      while (cur_item != NULL)
      {
            OnCommitItem *oc = (OnCommitItem *) lfirst(cur_item);

            if (isCommit ? oc->deleting_subid != InvalidSubTransactionId :
                  oc->creating_subid != InvalidSubTransactionId)
            {
                  /* cur_item must be removed */
                  on_commits = list_delete_cell(on_commits, cur_item, prev_item);
                  pfree(oc);
                  if (prev_item)
                        cur_item = lnext(prev_item);
                  else
                        cur_item = list_head(on_commits);
            }
            else
            {
                  /* cur_item must be preserved */
                  oc->creating_subid = InvalidSubTransactionId;
                  oc->deleting_subid = InvalidSubTransactionId;
                  prev_item = cur_item;
                  cur_item = lnext(prev_item);
            }
      }
}

/*
 * Post-subcommit or post-subabort cleanup for ON COMMIT management.
 *
 * During subabort, we can immediately remove entries created during this
 * subtransaction.      During subcommit, just relabel entries marked during
 * this subtransaction as being the parent's responsibility.
 */
void
AtEOSubXact_on_commit_actions(bool isCommit, SubTransactionId mySubid,
                                            SubTransactionId parentSubid)
{
      ListCell   *cur_item;
      ListCell   *prev_item;

      prev_item = NULL;
      cur_item = list_head(on_commits);

      while (cur_item != NULL)
      {
            OnCommitItem *oc = (OnCommitItem *) lfirst(cur_item);

            if (!isCommit && oc->creating_subid == mySubid)
            {
                  /* cur_item must be removed */
                  on_commits = list_delete_cell(on_commits, cur_item, prev_item);
                  pfree(oc);
                  if (prev_item)
                        cur_item = lnext(prev_item);
                  else
                        cur_item = list_head(on_commits);
            }
            else
            {
                  /* cur_item must be preserved */
                  if (oc->creating_subid == mySubid)
                        oc->creating_subid = parentSubid;
                  if (oc->deleting_subid == mySubid)
                        oc->deleting_subid = isCommit ? parentSubid : InvalidSubTransactionId;
                  prev_item = cur_item;
                  cur_item = lnext(prev_item);
            }
      }
}

Generated by  Doxygen 1.6.0   Back to index