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Sourcecode: postgresql-8.4 version File versions

parse_utilcmd.c

/*-------------------------------------------------------------------------
 *
 * parse_utilcmd.c
 *      Perform parse analysis work for various utility commands
 *
 * Formerly we did this work during parse_analyze() in analyze.c.  However
 * that is fairly unsafe in the presence of querytree caching, since any
 * database state that we depend on in making the transformations might be
 * obsolete by the time the utility command is executed; and utility commands
 * have no infrastructure for holding locks or rechecking plan validity.
 * Hence these functions are now called at the start of execution of their
 * respective utility commands.
 *
 * NOTE: in general we must avoid scribbling on the passed-in raw parse
 * tree, since it might be in a plan cache.  The simplest solution is
 * a quick copyObject() call before manipulating the query tree.
 *
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *    $PostgreSQL: pgsql/src/backend/parser/parse_utilcmd.c,v 2.21 2009/06/11 14:49:00 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/reloptions.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/namespace.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/tablecmds.h"
#include "commands/tablespace.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
#include "parser/gramparse.h"
#include "parser/parse_clause.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "parser/parse_type.h"
#include "parser/parse_utilcmd.h"
#include "rewrite/rewriteManip.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/relcache.h"
#include "utils/syscache.h"


/* State shared by transformCreateStmt and its subroutines */
typedef struct
{
      const char *stmtType;         /* "CREATE TABLE" or "ALTER TABLE" */
      RangeVar   *relation;         /* relation to create */
      Relation    rel;              /* opened/locked rel, if ALTER */
      List     *inhRelations; /* relations to inherit from */
      bool        isalter;          /* true if altering existing table */
      bool        hasoids;          /* does relation have an OID column? */
      List     *columns;            /* ColumnDef items */
      List     *ckconstraints;      /* CHECK constraints */
      List     *fkconstraints;      /* FOREIGN KEY constraints */
      List     *ixconstraints;      /* index-creating constraints */
      List     *inh_indexes;  /* cloned indexes from INCLUDING INDEXES */
      List     *blist;              /* "before list" of things to do before
                                                 * creating the table */
      List     *alist;              /* "after list" of things to do after creating
                                                 * the table */
      IndexStmt  *pkey;             /* PRIMARY KEY index, if any */
} CreateStmtContext;

/* State shared by transformCreateSchemaStmt and its subroutines */
typedef struct
{
      const char *stmtType;         /* "CREATE SCHEMA" or "ALTER SCHEMA" */
      char     *schemaname;         /* name of schema */
      char     *authid;             /* owner of schema */
      List     *sequences;          /* CREATE SEQUENCE items */
      List     *tables;             /* CREATE TABLE items */
      List     *views;              /* CREATE VIEW items */
      List     *indexes;            /* CREATE INDEX items */
      List     *triggers;           /* CREATE TRIGGER items */
      List     *grants;             /* GRANT items */
} CreateSchemaStmtContext;


static void transformColumnDefinition(ParseState *pstate,
                                      CreateStmtContext *cxt,
                                      ColumnDef *column);
static void transformTableConstraint(ParseState *pstate,
                                     CreateStmtContext *cxt,
                                     Constraint *constraint);
static void transformInhRelation(ParseState *pstate, CreateStmtContext *cxt,
                               InhRelation *inhrelation);
static IndexStmt *generateClonedIndexStmt(CreateStmtContext *cxt,
                                    Relation parent_index, AttrNumber *attmap);
static List *get_opclass(Oid opclass, Oid actual_datatype);
static void transformIndexConstraints(ParseState *pstate,
                                      CreateStmtContext *cxt);
static IndexStmt *transformIndexConstraint(Constraint *constraint,
                                     CreateStmtContext *cxt);
static void transformFKConstraints(ParseState *pstate,
                                 CreateStmtContext *cxt,
                                 bool skipValidation,
                                 bool isAddConstraint);
static void transformConstraintAttrs(List *constraintList);
static void transformColumnType(ParseState *pstate, ColumnDef *column);
static void setSchemaName(char *context_schema, char **stmt_schema_name);


/*
 * transformCreateStmt -
 *      parse analysis for CREATE TABLE
 *
 * Returns a List of utility commands to be done in sequence.  One of these
 * will be the transformed CreateStmt, but there may be additional actions
 * to be done before and after the actual DefineRelation() call.
 *
 * SQL92 allows constraints to be scattered all over, so thumb through
 * the columns and collect all constraints into one place.
 * If there are any implied indices (e.g. UNIQUE or PRIMARY KEY)
 * then expand those into multiple IndexStmt blocks.
 *      - thomas 1997-12-02
 */
List *
transformCreateStmt(CreateStmt *stmt, const char *queryString)
{
      ParseState *pstate;
      CreateStmtContext cxt;
      List     *result;
      List     *save_alist;
      ListCell   *elements;

      /*
       * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
       * overkill, but easy.)
       */
      stmt = (CreateStmt *) copyObject(stmt);

      /*
       * If the target relation name isn't schema-qualified, make it so.  This
       * prevents some corner cases in which added-on rewritten commands might
       * think they should apply to other relations that have the same name and
       * are earlier in the search path.  "istemp" is equivalent to a
       * specification of pg_temp, so no need for anything extra in that case.
       */
      if (stmt->relation->schemaname == NULL && !stmt->relation->istemp)
      {
            Oid               namespaceid = RangeVarGetCreationNamespace(stmt->relation);

            stmt->relation->schemaname = get_namespace_name(namespaceid);
      }

      /* Set up pstate */
      pstate = make_parsestate(NULL);
      pstate->p_sourcetext = queryString;

      cxt.stmtType = "CREATE TABLE";
      cxt.relation = stmt->relation;
      cxt.rel = NULL;
      cxt.inhRelations = stmt->inhRelations;
      cxt.isalter = false;
      cxt.columns = NIL;
      cxt.ckconstraints = NIL;
      cxt.fkconstraints = NIL;
      cxt.ixconstraints = NIL;
      cxt.inh_indexes = NIL;
      cxt.blist = NIL;
      cxt.alist = NIL;
      cxt.pkey = NULL;
      cxt.hasoids = interpretOidsOption(stmt->options);

      /*
       * Run through each primary element in the table creation clause. Separate
       * column defs from constraints, and do preliminary analysis.
       */
      foreach(elements, stmt->tableElts)
      {
            Node     *element = lfirst(elements);

            switch (nodeTag(element))
            {
                  case T_ColumnDef:
                        transformColumnDefinition(pstate, &cxt,
                                                              (ColumnDef *) element);
                        break;

                  case T_Constraint:
                        transformTableConstraint(pstate, &cxt,
                                                             (Constraint *) element);
                        break;

                  case T_FkConstraint:
                        /* No pre-transformation needed */
                        cxt.fkconstraints = lappend(cxt.fkconstraints, element);
                        break;

                  case T_InhRelation:
                        transformInhRelation(pstate, &cxt,
                                                       (InhRelation *) element);
                        break;

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

      /*
       * transformIndexConstraints wants cxt.alist to contain only index
       * statements, so transfer anything we already have into save_alist.
       */
      save_alist = cxt.alist;
      cxt.alist = NIL;

      Assert(stmt->constraints == NIL);

      /*
       * Postprocess constraints that give rise to index definitions.
       */
      transformIndexConstraints(pstate, &cxt);

      /*
       * Postprocess foreign-key constraints.
       */
      transformFKConstraints(pstate, &cxt, true, false);

      /*
       * Output results.
       */
      stmt->tableElts = cxt.columns;
      stmt->constraints = cxt.ckconstraints;

      result = lappend(cxt.blist, stmt);
      result = list_concat(result, cxt.alist);
      result = list_concat(result, save_alist);

      return result;
}

/*
 * transformColumnDefinition -
 *          transform a single ColumnDef within CREATE TABLE
 *          Also used in ALTER TABLE ADD COLUMN
 */
static void
transformColumnDefinition(ParseState *pstate, CreateStmtContext *cxt,
                                      ColumnDef *column)
{
      bool        is_serial;
      bool        saw_nullable;
      bool        saw_default;
      Constraint *constraint;
      ListCell   *clist;

      cxt->columns = lappend(cxt->columns, column);

      /* Check for SERIAL pseudo-types */
      is_serial = false;
      if (list_length(column->typename->names) == 1 &&
            !column->typename->pct_type)
      {
            char     *typname = strVal(linitial(column->typename->names));

            if (strcmp(typname, "serial") == 0 ||
                  strcmp(typname, "serial4") == 0)
            {
                  is_serial = true;
                  column->typename->names = NIL;
                  column->typename->typeid = INT4OID;
            }
            else if (strcmp(typname, "bigserial") == 0 ||
                         strcmp(typname, "serial8") == 0)
            {
                  is_serial = true;
                  column->typename->names = NIL;
                  column->typename->typeid = INT8OID;
            }

            /*
             * We have to reject "serial[]" explicitly, because once we've set
             * typeid, LookupTypeName won't notice arrayBounds.  We don't need any
             * special coding for serial(typmod) though.
             */
            if (is_serial && column->typename->arrayBounds != NIL)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("array of serial is not implemented")));
      }

      /* Do necessary work on the column type declaration */
      transformColumnType(pstate, column);

      /* Special actions for SERIAL pseudo-types */
      if (is_serial)
      {
            Oid               snamespaceid;
            char     *snamespace;
            char     *sname;
            char     *qstring;
            A_Const    *snamenode;
            TypeCast   *castnode;
            FuncCall   *funccallnode;
            CreateSeqStmt *seqstmt;
            AlterSeqStmt *altseqstmt;
            List     *attnamelist;

            /*
             * Determine namespace and name to use for the sequence.
             *
             * Although we use ChooseRelationName, it's not guaranteed that the
             * selected sequence name won't conflict; given sufficiently long
             * field names, two different serial columns in the same table could
             * be assigned the same sequence name, and we'd not notice since we
             * aren't creating the sequence quite yet.  In practice this seems
             * quite unlikely to be a problem, especially since few people would
             * need two serial columns in one table.
             */
            if (cxt->rel)
                  snamespaceid = RelationGetNamespace(cxt->rel);
            else
                  snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
            snamespace = get_namespace_name(snamespaceid);
            sname = ChooseRelationName(cxt->relation->relname,
                                                   column->colname,
                                                   "seq",
                                                   snamespaceid);

            ereport(NOTICE,
                        (errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
                                    cxt->stmtType, sname,
                                    cxt->relation->relname, column->colname)));

            /*
             * Build a CREATE SEQUENCE command to create the sequence object, and
             * add it to the list of things to be done before this CREATE/ALTER
             * TABLE.
             */
            seqstmt = makeNode(CreateSeqStmt);
            seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
            seqstmt->options = NIL;

            cxt->blist = lappend(cxt->blist, seqstmt);

            /*
             * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
             * as owned by this column, and add it to the list of things to be
             * done after this CREATE/ALTER TABLE.
             */
            altseqstmt = makeNode(AlterSeqStmt);
            altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
            attnamelist = list_make3(makeString(snamespace),
                                                 makeString(cxt->relation->relname),
                                                 makeString(column->colname));
            altseqstmt->options = list_make1(makeDefElem("owned_by",
                                                                               (Node *) attnamelist));

            cxt->alist = lappend(cxt->alist, altseqstmt);

            /*
             * Create appropriate constraints for SERIAL.  We do this in full,
             * rather than shortcutting, so that we will detect any conflicting
             * constraints the user wrote (like a different DEFAULT).
             *
             * Create an expression tree representing the function call
             * nextval('sequencename').  We cannot reduce the raw tree to cooked
             * form until after the sequence is created, but there's no need to do
             * so.
             */
            qstring = quote_qualified_identifier(snamespace, sname);
            snamenode = makeNode(A_Const);
            snamenode->val.type = T_String;
            snamenode->val.val.str = qstring;
            snamenode->location = -1;
            castnode = makeNode(TypeCast);
            castnode->typename = SystemTypeName("regclass");
            castnode->arg = (Node *) snamenode;
            castnode->location = -1;
            funccallnode = makeNode(FuncCall);
            funccallnode->funcname = SystemFuncName("nextval");
            funccallnode->args = list_make1(castnode);
            funccallnode->agg_star = false;
            funccallnode->agg_distinct = false;
            funccallnode->func_variadic = false;
            funccallnode->over = NULL;
            funccallnode->location = -1;

            constraint = makeNode(Constraint);
            constraint->contype = CONSTR_DEFAULT;
            constraint->raw_expr = (Node *) funccallnode;
            constraint->cooked_expr = NULL;
            constraint->keys = NIL;
            column->constraints = lappend(column->constraints, constraint);

            constraint = makeNode(Constraint);
            constraint->contype = CONSTR_NOTNULL;
            column->constraints = lappend(column->constraints, constraint);
      }

      /* Process column constraints, if any... */
      transformConstraintAttrs(column->constraints);

      saw_nullable = false;
      saw_default = false;

      foreach(clist, column->constraints)
      {
            constraint = lfirst(clist);

            /*
             * If this column constraint is a FOREIGN KEY constraint, then we fill
             * in the current attribute's name and throw it into the list of FK
             * constraints to be processed later.
             */
            if (IsA(constraint, FkConstraint))
            {
                  FkConstraint *fkconstraint = (FkConstraint *) constraint;

                  fkconstraint->fk_attrs = list_make1(makeString(column->colname));
                  cxt->fkconstraints = lappend(cxt->fkconstraints, fkconstraint);
                  continue;
            }

            Assert(IsA(constraint, Constraint));

            switch (constraint->contype)
            {
                  case CONSTR_NULL:
                        if (saw_nullable && column->is_not_null)
                              ereport(ERROR,
                                          (errcode(ERRCODE_SYNTAX_ERROR),
                                           errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                                  column->colname, cxt->relation->relname)));
                        column->is_not_null = FALSE;
                        saw_nullable = true;
                        break;

                  case CONSTR_NOTNULL:
                        if (saw_nullable && !column->is_not_null)
                              ereport(ERROR,
                                          (errcode(ERRCODE_SYNTAX_ERROR),
                                           errmsg("conflicting NULL/NOT NULL declarations for column \"%s\" of table \"%s\"",
                                                  column->colname, cxt->relation->relname)));
                        column->is_not_null = TRUE;
                        saw_nullable = true;
                        break;

                  case CONSTR_DEFAULT:
                        if (saw_default)
                              ereport(ERROR,
                                          (errcode(ERRCODE_SYNTAX_ERROR),
                                           errmsg("multiple default values specified for column \"%s\" of table \"%s\"",
                                                  column->colname, cxt->relation->relname)));
                        column->raw_default = constraint->raw_expr;
                        Assert(constraint->cooked_expr == NULL);
                        saw_default = true;
                        break;

                  case CONSTR_PRIMARY:
                  case CONSTR_UNIQUE:
                        if (constraint->keys == NIL)
                              constraint->keys = list_make1(makeString(column->colname));
                        cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
                        break;

                  case CONSTR_CHECK:
                        cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
                        break;

                  case CONSTR_ATTR_DEFERRABLE:
                  case CONSTR_ATTR_NOT_DEFERRABLE:
                  case CONSTR_ATTR_DEFERRED:
                  case CONSTR_ATTR_IMMEDIATE:
                        /* transformConstraintAttrs took care of these */
                        break;

                  default:
                        elog(ERROR, "unrecognized constraint type: %d",
                               constraint->contype);
                        break;
            }
      }
}

/*
 * transformTableConstraint
 *          transform a Constraint node within CREATE TABLE or ALTER TABLE
 */
static void
transformTableConstraint(ParseState *pstate, CreateStmtContext *cxt,
                                     Constraint *constraint)
{
      switch (constraint->contype)
      {
            case CONSTR_PRIMARY:
            case CONSTR_UNIQUE:
                  cxt->ixconstraints = lappend(cxt->ixconstraints, constraint);
                  break;

            case CONSTR_CHECK:
                  cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
                  break;

            case CONSTR_NULL:
            case CONSTR_NOTNULL:
            case CONSTR_DEFAULT:
            case CONSTR_ATTR_DEFERRABLE:
            case CONSTR_ATTR_NOT_DEFERRABLE:
            case CONSTR_ATTR_DEFERRED:
            case CONSTR_ATTR_IMMEDIATE:
                  elog(ERROR, "invalid context for constraint type %d",
                         constraint->contype);
                  break;

            default:
                  elog(ERROR, "unrecognized constraint type: %d",
                         constraint->contype);
                  break;
      }
}

/*
 * transformInhRelation
 *
 * Change the LIKE <subtable> portion of a CREATE TABLE statement into
 * column definitions which recreate the user defined column portions of
 * <subtable>.
 */
static void
transformInhRelation(ParseState *pstate, CreateStmtContext *cxt,
                               InhRelation *inhRelation)
{
      AttrNumber  parent_attno;
      Relation    relation;
      TupleDesc   tupleDesc;
      TupleConstr *constr;
      AclResult   aclresult;
      bool        including_defaults = false;
      bool        including_constraints = false;
      bool        including_indexes = false;
      ListCell   *elem;

      relation = parserOpenTable(pstate, inhRelation->relation, AccessShareLock);

      if (relation->rd_rel->relkind != RELKIND_RELATION)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("inherited relation \"%s\" is not a table",
                                    inhRelation->relation->relname)));

      /*
       * Check for SELECT privilages
       */
      aclresult = pg_class_aclcheck(RelationGetRelid(relation), GetUserId(),
                                                  ACL_SELECT);
      if (aclresult != ACLCHECK_OK)
            aclcheck_error(aclresult, ACL_KIND_CLASS,
                                 RelationGetRelationName(relation));

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

      foreach(elem, inhRelation->options)
      {
            int               option = lfirst_int(elem);

            switch (option)
            {
                  case CREATE_TABLE_LIKE_INCLUDING_DEFAULTS:
                        including_defaults = true;
                        break;
                  case CREATE_TABLE_LIKE_EXCLUDING_DEFAULTS:
                        including_defaults = false;
                        break;
                  case CREATE_TABLE_LIKE_INCLUDING_CONSTRAINTS:
                        including_constraints = true;
                        break;
                  case CREATE_TABLE_LIKE_EXCLUDING_CONSTRAINTS:
                        including_constraints = false;
                        break;
                  case CREATE_TABLE_LIKE_INCLUDING_INDEXES:
                        including_indexes = true;
                        break;
                  case CREATE_TABLE_LIKE_EXCLUDING_INDEXES:
                        including_indexes = false;
                        break;
                  default:
                        elog(ERROR, "unrecognized CREATE TABLE LIKE option: %d",
                               option);
            }
      }

      /*
       * Insert the copied attributes into the cxt for the new table definition.
       */
      for (parent_attno = 1; parent_attno <= tupleDesc->natts;
             parent_attno++)
      {
            Form_pg_attribute attribute = tupleDesc->attrs[parent_attno - 1];
            char     *attributeName = NameStr(attribute->attname);
            ColumnDef  *def;

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

            /*
             * Create a new column, which is marked as NOT inherited.
             *
             * For constraints, ONLY the NOT NULL constraint is inherited by the
             * new column definition per SQL99.
             */
            def = makeNode(ColumnDef);
            def->colname = pstrdup(attributeName);
            def->typename = makeTypeNameFromOid(attribute->atttypid,
                                                                  attribute->atttypmod);
            def->inhcount = 0;
            def->is_local = true;
            def->is_not_null = attribute->attnotnull;
            def->raw_default = NULL;
            def->cooked_default = NULL;
            def->constraints = NIL;

            /*
             * Add to column list
             */
            cxt->columns = lappend(cxt->columns, def);

            /*
             * Copy default, if present and the default has been requested
             */
            if (attribute->atthasdef && including_defaults)
            {
                  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.
                   */

                  def->cooked_default = pstrdup(this_default);
            }
      }

      /*
       * Copy CHECK constraints if requested, being careful to adjust attribute
       * numbers
       */
      if (including_constraints && tupleDesc->constr)
      {
            AttrNumber *attmap = varattnos_map_schema(tupleDesc, cxt->columns);
            int               ccnum;

            for (ccnum = 0; ccnum < tupleDesc->constr->num_check; ccnum++)
            {
                  char     *ccname = tupleDesc->constr->check[ccnum].ccname;
                  char     *ccbin = tupleDesc->constr->check[ccnum].ccbin;
                  Node     *ccbin_node = stringToNode(ccbin);
                  Constraint *n = makeNode(Constraint);

                  change_varattnos_of_a_node(ccbin_node, attmap);

                  n->contype = CONSTR_CHECK;
                  n->name = pstrdup(ccname);
                  n->raw_expr = NULL;
                  n->cooked_expr = nodeToString(ccbin_node);
                  n->indexspace = NULL;
                  cxt->ckconstraints = lappend(cxt->ckconstraints, (Node *) n);
            }
      }

      /*
       * Likewise, copy indexes if requested
       */
      if (including_indexes && relation->rd_rel->relhasindex)
      {
            AttrNumber *attmap = varattnos_map_schema(tupleDesc, cxt->columns);
            List     *parent_indexes;
            ListCell   *l;

            parent_indexes = RelationGetIndexList(relation);

            foreach(l, parent_indexes)
            {
                  Oid               parent_index_oid = lfirst_oid(l);
                  Relation    parent_index;
                  IndexStmt  *index_stmt;

                  parent_index = index_open(parent_index_oid, AccessShareLock);

                  /* Build CREATE INDEX statement to recreate the parent_index */
                  index_stmt = generateClonedIndexStmt(cxt, parent_index, attmap);

                  /* Save it in the inh_indexes list for the time being */
                  cxt->inh_indexes = lappend(cxt->inh_indexes, index_stmt);

                  index_close(parent_index, AccessShareLock);
            }
      }

      /*
       * 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);
}

/*
 * Generate an IndexStmt node using information from an already existing index
 * "source_idx".  Attribute numbers should be adjusted according to attmap.
 */
static IndexStmt *
generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
                                    AttrNumber *attmap)
{
      Oid               source_relid = RelationGetRelid(source_idx);
      HeapTuple   ht_idxrel;
      HeapTuple   ht_idx;
      Form_pg_class idxrelrec;
      Form_pg_index idxrec;
      Form_pg_am  amrec;
      oidvector  *indclass;
      IndexStmt  *index;
      List     *indexprs;
      ListCell   *indexpr_item;
      Oid               indrelid;
      int               keyno;
      Oid               keycoltype;
      Datum       datum;
      bool        isnull;

      /*
       * Fetch pg_class tuple of source index.  We can't use the copy in the
       * relcache entry because it doesn't include optional fields.
       */
      ht_idxrel = SearchSysCache(RELOID,
                                             ObjectIdGetDatum(source_relid),
                                             0, 0, 0);
      if (!HeapTupleIsValid(ht_idxrel))
            elog(ERROR, "cache lookup failed for relation %u", source_relid);
      idxrelrec = (Form_pg_class) GETSTRUCT(ht_idxrel);

      /* Fetch pg_index tuple for source index from relcache entry */
      ht_idx = source_idx->rd_indextuple;
      idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
      indrelid = idxrec->indrelid;

      /* Fetch pg_am tuple for source index from relcache entry */
      amrec = source_idx->rd_am;

      /* Must get indclass the hard way, since it's not stored in relcache */
      datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                                          Anum_pg_index_indclass, &isnull);
      Assert(!isnull);
      indclass = (oidvector *) DatumGetPointer(datum);

      /* Begin building the IndexStmt */
      index = makeNode(IndexStmt);
      index->relation = cxt->relation;
      index->accessMethod = pstrdup(NameStr(amrec->amname));
      if (OidIsValid(idxrelrec->reltablespace))
            index->tableSpace = get_tablespace_name(idxrelrec->reltablespace);
      else
            index->tableSpace = NULL;
      index->unique = idxrec->indisunique;
      index->primary = idxrec->indisprimary;
      index->concurrent = false;

      /*
       * We don't try to preserve the name of the source index; instead, just
       * let DefineIndex() choose a reasonable name.
       */
      index->idxname = NULL;

      /*
       * If the index is marked PRIMARY, it's certainly from a constraint; else,
       * if it's not marked UNIQUE, it certainly isn't; else, we have to search
       * pg_depend to see if there's an associated unique constraint.
       */
      if (index->primary)
            index->isconstraint = true;
      else if (!index->unique)
            index->isconstraint = false;
      else
            index->isconstraint = OidIsValid(get_index_constraint(source_relid));

      /* Get the index expressions, if any */
      datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                                          Anum_pg_index_indexprs, &isnull);
      if (!isnull)
      {
            char     *exprsString;

            exprsString = TextDatumGetCString(datum);
            indexprs = (List *) stringToNode(exprsString);
      }
      else
            indexprs = NIL;

      /* Build the list of IndexElem */
      index->indexParams = NIL;

      indexpr_item = list_head(indexprs);
      for (keyno = 0; keyno < idxrec->indnatts; keyno++)
      {
            IndexElem  *iparam;
            AttrNumber  attnum = idxrec->indkey.values[keyno];
            int16       opt = source_idx->rd_indoption[keyno];

            iparam = makeNode(IndexElem);

            if (AttributeNumberIsValid(attnum))
            {
                  /* Simple index column */
                  char     *attname;

                  attname = get_relid_attribute_name(indrelid, attnum);
                  keycoltype = get_atttype(indrelid, attnum);

                  iparam->name = attname;
                  iparam->expr = NULL;
            }
            else
            {
                  /* Expressional index */
                  Node     *indexkey;

                  if (indexpr_item == NULL)
                        elog(ERROR, "too few entries in indexprs list");
                  indexkey = (Node *) lfirst(indexpr_item);
                  indexpr_item = lnext(indexpr_item);

                  /* OK to modify indexkey since we are working on a private copy */
                  change_varattnos_of_a_node(indexkey, attmap);

                  iparam->name = NULL;
                  iparam->expr = indexkey;

                  keycoltype = exprType(indexkey);
            }

            /* Add the operator class name, if non-default */
            iparam->opclass = get_opclass(indclass->values[keyno], keycoltype);

            iparam->ordering = SORTBY_DEFAULT;
            iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;

            /* Adjust options if necessary */
            if (amrec->amcanorder)
            {
                  /*
                   * If it supports sort ordering, copy DESC and NULLS opts. Don't
                   * set non-default settings unnecessarily, though, so as to
                   * improve the chance of recognizing equivalence to constraint
                   * indexes.
                   */
                  if (opt & INDOPTION_DESC)
                  {
                        iparam->ordering = SORTBY_DESC;
                        if ((opt & INDOPTION_NULLS_FIRST) == 0)
                              iparam->nulls_ordering = SORTBY_NULLS_LAST;
                  }
                  else
                  {
                        if (opt & INDOPTION_NULLS_FIRST)
                              iparam->nulls_ordering = SORTBY_NULLS_FIRST;
                  }
            }

            index->indexParams = lappend(index->indexParams, iparam);
      }

      /* Copy reloptions if any */
      datum = SysCacheGetAttr(RELOID, ht_idxrel,
                                          Anum_pg_class_reloptions, &isnull);
      if (!isnull)
            index->options = untransformRelOptions(datum);

      /* If it's a partial index, decompile and append the predicate */
      datum = SysCacheGetAttr(INDEXRELID, ht_idx,
                                          Anum_pg_index_indpred, &isnull);
      if (!isnull)
      {
            char     *pred_str;

            /* Convert text string to node tree */
            pred_str = TextDatumGetCString(datum);
            index->whereClause = (Node *) stringToNode(pred_str);
            /* Adjust attribute numbers */
            change_varattnos_of_a_node(index->whereClause, attmap);
      }

      /* Clean up */
      ReleaseSysCache(ht_idxrel);

      return index;
}

/*
 * get_opclass                - fetch name of an index operator class
 *
 * If the opclass is the default for the given actual_datatype, then
 * the return value is NIL.
 */
static List *
get_opclass(Oid opclass, Oid actual_datatype)
{
      HeapTuple   ht_opc;
      Form_pg_opclass opc_rec;
      List     *result = NIL;

      ht_opc = SearchSysCache(CLAOID,
                                          ObjectIdGetDatum(opclass),
                                          0, 0, 0);
      if (!HeapTupleIsValid(ht_opc))
            elog(ERROR, "cache lookup failed for opclass %u", opclass);
      opc_rec = (Form_pg_opclass) GETSTRUCT(ht_opc);

      if (GetDefaultOpClass(actual_datatype, opc_rec->opcmethod) != opclass)
      {
            /* For simplicity, we always schema-qualify the name */
            char     *nsp_name = get_namespace_name(opc_rec->opcnamespace);
            char     *opc_name = pstrdup(NameStr(opc_rec->opcname));

            result = list_make2(makeString(nsp_name), makeString(opc_name));
      }

      ReleaseSysCache(ht_opc);
      return result;
}


/*
 * transformIndexConstraints
 *          Handle UNIQUE and PRIMARY KEY constraints, which create indexes.
 *          We also merge in any index definitions arising from
 *          LIKE ... INCLUDING INDEXES.
 */
static void
transformIndexConstraints(ParseState *pstate, CreateStmtContext *cxt)
{
      IndexStmt  *index;
      List     *indexlist = NIL;
      ListCell   *lc;

      /*
       * Run through the constraints that need to generate an index. For PRIMARY
       * KEY, mark each column as NOT NULL and create an index. For UNIQUE,
       * create an index as for PRIMARY KEY, but do not insist on NOT NULL.
       */
      foreach(lc, cxt->ixconstraints)
      {
            Constraint *constraint = (Constraint *) lfirst(lc);

            Assert(IsA(constraint, Constraint));
            Assert(constraint->contype == CONSTR_PRIMARY ||
                     constraint->contype == CONSTR_UNIQUE);

            index = transformIndexConstraint(constraint, cxt);

            indexlist = lappend(indexlist, index);
      }

      /* Add in any indexes defined by LIKE ... INCLUDING INDEXES */
      foreach(lc, cxt->inh_indexes)
      {
            index = (IndexStmt *) lfirst(lc);

            if (index->primary)
            {
                  if (cxt->pkey != NULL)
                        ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                                     errmsg("multiple primary keys for table \"%s\" are not allowed",
                                                cxt->relation->relname)));
                  cxt->pkey = index;
            }

            indexlist = lappend(indexlist, index);
      }

      /*
       * Scan the index list and remove any redundant index specifications. This
       * can happen if, for instance, the user writes UNIQUE PRIMARY KEY. A
       * strict reading of SQL92 would suggest raising an error instead, but
       * that strikes me as too anal-retentive. - tgl 2001-02-14
       *
       * XXX in ALTER TABLE case, it'd be nice to look for duplicate
       * pre-existing indexes, too.
       */
      Assert(cxt->alist == NIL);
      if (cxt->pkey != NULL)
      {
            /* Make sure we keep the PKEY index in preference to others... */
            cxt->alist = list_make1(cxt->pkey);
      }

      foreach(lc, indexlist)
      {
            bool        keep = true;
            ListCell   *k;

            index = lfirst(lc);

            /* if it's pkey, it's already in cxt->alist */
            if (index == cxt->pkey)
                  continue;

            foreach(k, cxt->alist)
            {
                  IndexStmt  *priorindex = lfirst(k);

                  if (equal(index->indexParams, priorindex->indexParams) &&
                        equal(index->whereClause, priorindex->whereClause) &&
                        strcmp(index->accessMethod, priorindex->accessMethod) == 0)
                  {
                        priorindex->unique |= index->unique;

                        /*
                         * If the prior index is as yet unnamed, and this one is
                         * named, then transfer the name to the prior index. This
                         * ensures that if we have named and unnamed constraints,
                         * we'll use (at least one of) the names for the index.
                         */
                        if (priorindex->idxname == NULL)
                              priorindex->idxname = index->idxname;
                        keep = false;
                        break;
                  }
            }

            if (keep)
                  cxt->alist = lappend(cxt->alist, index);
      }
}

/*
 * transformIndexConstraint
 *          Transform one UNIQUE or PRIMARY KEY constraint for
 *          transformIndexConstraints.
 */
static IndexStmt *
transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
{
      IndexStmt  *index;
      ListCell   *keys;
      IndexElem  *iparam;

      index = makeNode(IndexStmt);

      index->unique = true;
      index->primary = (constraint->contype == CONSTR_PRIMARY);
      if (index->primary)
      {
            if (cxt->pkey != NULL)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                   errmsg("multiple primary keys for table \"%s\" are not allowed",
                              cxt->relation->relname)));
            cxt->pkey = index;

            /*
             * In ALTER TABLE case, a primary index might already exist, but
             * DefineIndex will check for it.
             */
      }
      index->isconstraint = true;

      if (constraint->name != NULL)
            index->idxname = pstrdup(constraint->name);
      else
            index->idxname = NULL;  /* DefineIndex will choose name */

      index->relation = cxt->relation;
      index->accessMethod = DEFAULT_INDEX_TYPE;
      index->options = constraint->options;
      index->tableSpace = constraint->indexspace;
      index->indexParams = NIL;
      index->whereClause = NULL;
      index->concurrent = false;

      /*
       * Make sure referenced keys exist.  If we are making a PRIMARY KEY index,
       * also make sure they are NOT NULL, if possible. (Although we could leave
       * it to DefineIndex to mark the columns NOT NULL, it's more efficient to
       * get it right the first time.)
       */
      foreach(keys, constraint->keys)
      {
            char     *key = strVal(lfirst(keys));
            bool        found = false;
            ColumnDef  *column = NULL;
            ListCell   *columns;

            foreach(columns, cxt->columns)
            {
                  column = (ColumnDef *) lfirst(columns);
                  Assert(IsA(column, ColumnDef));
                  if (strcmp(column->colname, key) == 0)
                  {
                        found = true;
                        break;
                  }
            }
            if (found)
            {
                  /* found column in the new table; force it to be NOT NULL */
                  if (constraint->contype == CONSTR_PRIMARY)
                        column->is_not_null = TRUE;
            }
            else if (SystemAttributeByName(key, cxt->hasoids) != NULL)
            {
                  /*
                   * column will be a system column in the new table, so accept it.
                   * System columns can't ever be null, so no need to worry about
                   * PRIMARY/NOT NULL constraint.
                   */
                  found = true;
            }
            else if (cxt->inhRelations)
            {
                  /* try inherited tables */
                  ListCell   *inher;

                  foreach(inher, cxt->inhRelations)
                  {
                        RangeVar   *inh = (RangeVar *) lfirst(inher);
                        Relation    rel;
                        int               count;

                        Assert(IsA(inh, RangeVar));
                        rel = heap_openrv(inh, AccessShareLock);
                        if (rel->rd_rel->relkind != RELKIND_RELATION)
                              ereport(ERROR,
                                          (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                                       errmsg("inherited relation \"%s\" is not a table",
                                                  inh->relname)));
                        for (count = 0; count < rel->rd_att->natts; count++)
                        {
                              Form_pg_attribute inhattr = rel->rd_att->attrs[count];
                              char     *inhname = NameStr(inhattr->attname);

                              if (inhattr->attisdropped)
                                    continue;
                              if (strcmp(key, inhname) == 0)
                              {
                                    found = true;

                                    /*
                                     * We currently have no easy way to force an inherited
                                     * column to be NOT NULL at creation, if its parent
                                     * wasn't so already. We leave it to DefineIndex to
                                     * fix things up in this case.
                                     */
                                    break;
                              }
                        }
                        heap_close(rel, NoLock);
                        if (found)
                              break;
                  }
            }

            /*
             * In the ALTER TABLE case, don't complain about index keys not
             * created in the command; they may well exist already. DefineIndex
             * will complain about them if not, and will also take care of marking
             * them NOT NULL.
             */
            if (!found && !cxt->isalter)
                  ereport(ERROR,
                              (errcode(ERRCODE_UNDEFINED_COLUMN),
                               errmsg("column \"%s\" named in key does not exist",
                                          key)));

            /* Check for PRIMARY KEY(foo, foo) */
            foreach(columns, index->indexParams)
            {
                  iparam = (IndexElem *) lfirst(columns);
                  if (iparam->name && strcmp(key, iparam->name) == 0)
                  {
                        if (index->primary)
                              ereport(ERROR,
                                          (errcode(ERRCODE_DUPLICATE_COLUMN),
                                           errmsg("column \"%s\" appears twice in primary key constraint",
                                                      key)));
                        else
                              ereport(ERROR,
                                          (errcode(ERRCODE_DUPLICATE_COLUMN),
                              errmsg("column \"%s\" appears twice in unique constraint",
                                       key)));
                  }
            }

            /* OK, add it to the index definition */
            iparam = makeNode(IndexElem);
            iparam->name = pstrdup(key);
            iparam->expr = NULL;
            iparam->opclass = NIL;
            iparam->ordering = SORTBY_DEFAULT;
            iparam->nulls_ordering = SORTBY_NULLS_DEFAULT;
            index->indexParams = lappend(index->indexParams, iparam);
      }

      return index;
}

/*
 * transformFKConstraints
 *          handle FOREIGN KEY constraints
 */
static void
transformFKConstraints(ParseState *pstate, CreateStmtContext *cxt,
                                 bool skipValidation, bool isAddConstraint)
{
      ListCell   *fkclist;

      if (cxt->fkconstraints == NIL)
            return;

      /*
       * If CREATE TABLE or adding a column with NULL default, we can safely
       * skip validation of the constraint.
       */
      if (skipValidation)
      {
            foreach(fkclist, cxt->fkconstraints)
            {
                  FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);

                  fkconstraint->skip_validation = true;
            }
      }

      /*
       * For CREATE TABLE or ALTER TABLE ADD COLUMN, gin up an ALTER TABLE ADD
       * CONSTRAINT command to execute after the basic command is complete. (If
       * called from ADD CONSTRAINT, that routine will add the FK constraints to
       * its own subcommand list.)
       *
       * Note: the ADD CONSTRAINT command must also execute after any index
       * creation commands.  Thus, this should run after
       * transformIndexConstraints, so that the CREATE INDEX commands are
       * already in cxt->alist.
       */
      if (!isAddConstraint)
      {
            AlterTableStmt *alterstmt = makeNode(AlterTableStmt);

            alterstmt->relation = cxt->relation;
            alterstmt->cmds = NIL;
            alterstmt->relkind = OBJECT_TABLE;

            foreach(fkclist, cxt->fkconstraints)
            {
                  FkConstraint *fkconstraint = (FkConstraint *) lfirst(fkclist);
                  AlterTableCmd *altercmd = makeNode(AlterTableCmd);

                  altercmd->subtype = AT_ProcessedConstraint;
                  altercmd->name = NULL;
                  altercmd->def = (Node *) fkconstraint;
                  alterstmt->cmds = lappend(alterstmt->cmds, altercmd);
            }

            cxt->alist = lappend(cxt->alist, alterstmt);
      }
}

/*
 * transformIndexStmt - parse analysis for CREATE INDEX
 *
 * Note: this is a no-op for an index not using either index expressions or
 * a predicate expression.    There are several code paths that create indexes
 * without bothering to call this, because they know they don't have any
 * such expressions to deal with.
 */
IndexStmt *
transformIndexStmt(IndexStmt *stmt, const char *queryString)
{
      Relation    rel;
      ParseState *pstate;
      RangeTblEntry *rte;
      ListCell   *l;

      /*
       * We must not scribble on the passed-in IndexStmt, so copy it.  (This is
       * overkill, but easy.)
       */
      stmt = (IndexStmt *) copyObject(stmt);

      /*
       * Open the parent table with appropriate locking.    We must do this
       * because addRangeTableEntry() would acquire only AccessShareLock,
       * leaving DefineIndex() needing to do a lock upgrade with consequent risk
       * of deadlock.  Make sure this stays in sync with the type of lock
       * DefineIndex() wants.
       */
      rel = heap_openrv(stmt->relation,
                          (stmt->concurrent ? ShareUpdateExclusiveLock : ShareLock));

      /* Set up pstate */
      pstate = make_parsestate(NULL);
      pstate->p_sourcetext = queryString;

      /*
       * Put the parent table into the rtable so that the expressions can refer
       * to its fields without qualification.
       */
      rte = addRangeTableEntry(pstate, stmt->relation, NULL, false, true);

      /* no to join list, yes to namespaces */
      addRTEtoQuery(pstate, rte, false, true, true);

      /* take care of the where clause */
      if (stmt->whereClause)
            stmt->whereClause = transformWhereClause(pstate,
                                                                         stmt->whereClause,
                                                                         "WHERE");

      /* take care of any index expressions */
      foreach(l, stmt->indexParams)
      {
            IndexElem  *ielem = (IndexElem *) lfirst(l);

            if (ielem->expr)
            {
                  ielem->expr = transformExpr(pstate, ielem->expr);

                  /*
                   * We check only that the result type is legitimate; this is for
                   * consistency with what transformWhereClause() checks for the
                   * predicate.  DefineIndex() will make more checks.
                   */
                  if (expression_returns_set(ielem->expr))
                        ereport(ERROR,
                                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                                     errmsg("index expression cannot return a set")));
            }
      }

      /*
       * Check that only the base rel is mentioned.
       */
      if (list_length(pstate->p_rtable) != 1)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
                         errmsg("index expressions and predicates can refer only to the table being indexed")));

      free_parsestate(pstate);

      /* Close relation, but keep the lock */
      heap_close(rel, NoLock);

      return stmt;
}


/*
 * transformRuleStmt -
 *      transform a CREATE RULE Statement. The action is a list of parse
 *      trees which is transformed into a list of query trees, and we also
 *      transform the WHERE clause if any.
 *
 * actions and whereClause are output parameters that receive the
 * transformed results.
 *
 * Note that we must not scribble on the passed-in RuleStmt, so we do
 * copyObject() on the actions and WHERE clause.
 */
void
transformRuleStmt(RuleStmt *stmt, const char *queryString,
                          List **actions, Node **whereClause)
{
      Relation    rel;
      ParseState *pstate;
      RangeTblEntry *oldrte;
      RangeTblEntry *newrte;

      /*
       * To avoid deadlock, make sure the first thing we do is grab
       * AccessExclusiveLock on the target relation.  This will be needed by
       * DefineQueryRewrite(), and we don't want to grab a lesser lock
       * beforehand.
       */
      rel = heap_openrv(stmt->relation, AccessExclusiveLock);

      /* Set up pstate */
      pstate = make_parsestate(NULL);
      pstate->p_sourcetext = queryString;

      /*
       * NOTE: 'OLD' must always have a varno equal to 1 and 'NEW' equal to 2.
       * Set up their RTEs in the main pstate for use in parsing the rule
       * qualification.
       */
      oldrte = addRangeTableEntryForRelation(pstate, rel,
                                                               makeAlias("*OLD*", NIL),
                                                               false, false);
      newrte = addRangeTableEntryForRelation(pstate, rel,
                                                               makeAlias("*NEW*", NIL),
                                                               false, false);
      /* Must override addRangeTableEntry's default access-check flags */
      oldrte->requiredPerms = 0;
      newrte->requiredPerms = 0;

      /*
       * They must be in the namespace too for lookup purposes, but only add the
       * one(s) that are relevant for the current kind of rule.  In an UPDATE
       * rule, quals must refer to OLD.field or NEW.field to be unambiguous, but
       * there's no need to be so picky for INSERT & DELETE.  We do not add them
       * to the joinlist.
       */
      switch (stmt->event)
      {
            case CMD_SELECT:
                  addRTEtoQuery(pstate, oldrte, false, true, true);
                  break;
            case CMD_UPDATE:
                  addRTEtoQuery(pstate, oldrte, false, true, true);
                  addRTEtoQuery(pstate, newrte, false, true, true);
                  break;
            case CMD_INSERT:
                  addRTEtoQuery(pstate, newrte, false, true, true);
                  break;
            case CMD_DELETE:
                  addRTEtoQuery(pstate, oldrte, false, true, true);
                  break;
            default:
                  elog(ERROR, "unrecognized event type: %d",
                         (int) stmt->event);
                  break;
      }

      /* take care of the where clause */
      *whereClause = transformWhereClause(pstate,
                                                        (Node *) copyObject(stmt->whereClause),
                                                            "WHERE");

      if (list_length(pstate->p_rtable) != 2)         /* naughty, naughty... */
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("rule WHERE condition cannot contain references to other relations")));

      /* aggregates not allowed (but subselects are okay) */
      if (pstate->p_hasAggs)
            ereport(ERROR,
                        (errcode(ERRCODE_GROUPING_ERROR),
               errmsg("cannot use aggregate function in rule WHERE condition")));
      if (pstate->p_hasWindowFuncs)
            ereport(ERROR,
                        (errcode(ERRCODE_WINDOWING_ERROR),
                    errmsg("cannot use window function in rule WHERE condition")));

      /*
       * 'instead nothing' rules with a qualification need a query rangetable so
       * the rewrite handler can add the negated rule qualification to the
       * original query. We create a query with the new command type CMD_NOTHING
       * here that is treated specially by the rewrite system.
       */
      if (stmt->actions == NIL)
      {
            Query    *nothing_qry = makeNode(Query);

            nothing_qry->commandType = CMD_NOTHING;
            nothing_qry->rtable = pstate->p_rtable;
            nothing_qry->jointree = makeFromExpr(NIL, NULL);            /* no join wanted */

            *actions = list_make1(nothing_qry);
      }
      else
      {
            ListCell   *l;
            List     *newactions = NIL;

            /*
             * transform each statement, like parse_sub_analyze()
             */
            foreach(l, stmt->actions)
            {
                  Node     *action = (Node *) lfirst(l);
                  ParseState *sub_pstate = make_parsestate(NULL);
                  Query    *sub_qry,
                                 *top_subqry;
                  bool        has_old,
                                    has_new;

                  /*
                   * Since outer ParseState isn't parent of inner, have to pass down
                   * the query text by hand.
                   */
                  sub_pstate->p_sourcetext = queryString;

                  /*
                   * Set up OLD/NEW in the rtable for this statement.  The entries
                   * are added only to relnamespace, not varnamespace, because we
                   * don't want them to be referred to by unqualified field names
                   * nor "*" in the rule actions.  We decide later whether to put
                   * them in the joinlist.
                   */
                  oldrte = addRangeTableEntryForRelation(sub_pstate, rel,
                                                                           makeAlias("*OLD*", NIL),
                                                                           false, false);
                  newrte = addRangeTableEntryForRelation(sub_pstate, rel,
                                                                           makeAlias("*NEW*", NIL),
                                                                           false, false);
                  oldrte->requiredPerms = 0;
                  newrte->requiredPerms = 0;
                  addRTEtoQuery(sub_pstate, oldrte, false, true, false);
                  addRTEtoQuery(sub_pstate, newrte, false, true, false);

                  /* Transform the rule action statement */
                  top_subqry = transformStmt(sub_pstate,
                                                         (Node *) copyObject(action));

                  /*
                   * We cannot support utility-statement actions (eg NOTIFY) with
                   * nonempty rule WHERE conditions, because there's no way to make
                   * the utility action execute conditionally.
                   */
                  if (top_subqry->commandType == CMD_UTILITY &&
                        *whereClause != NULL)
                        ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                     errmsg("rules with WHERE conditions can only have SELECT, INSERT, UPDATE, or DELETE actions")));

                  /*
                   * If the action is INSERT...SELECT, OLD/NEW have been pushed down
                   * into the SELECT, and that's what we need to look at. (Ugly
                   * kluge ... try to fix this when we redesign querytrees.)
                   */
                  sub_qry = getInsertSelectQuery(top_subqry, NULL);

                  /*
                   * If the sub_qry is a setop, we cannot attach any qualifications
                   * to it, because the planner won't notice them.  This could
                   * perhaps be relaxed someday, but for now, we may as well reject
                   * such a rule immediately.
                   */
                  if (sub_qry->setOperations != NULL && *whereClause != NULL)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));

                  /*
                   * Validate action's use of OLD/NEW, qual too
                   */
                  has_old =
                        rangeTableEntry_used((Node *) sub_qry, PRS2_OLD_VARNO, 0) ||
                        rangeTableEntry_used(*whereClause, PRS2_OLD_VARNO, 0);
                  has_new =
                        rangeTableEntry_used((Node *) sub_qry, PRS2_NEW_VARNO, 0) ||
                        rangeTableEntry_used(*whereClause, PRS2_NEW_VARNO, 0);

                  switch (stmt->event)
                  {
                        case CMD_SELECT:
                              if (has_old)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                                 errmsg("ON SELECT rule cannot use OLD")));
                              if (has_new)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                                 errmsg("ON SELECT rule cannot use NEW")));
                              break;
                        case CMD_UPDATE:
                              /* both are OK */
                              break;
                        case CMD_INSERT:
                              if (has_old)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                                 errmsg("ON INSERT rule cannot use OLD")));
                              break;
                        case CMD_DELETE:
                              if (has_new)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                                 errmsg("ON DELETE rule cannot use NEW")));
                              break;
                        default:
                              elog(ERROR, "unrecognized event type: %d",
                                     (int) stmt->event);
                              break;
                  }

                  /*
                   * For efficiency's sake, add OLD to the rule action's jointree
                   * only if it was actually referenced in the statement or qual.
                   *
                   * For INSERT, NEW is not really a relation (only a reference to
                   * the to-be-inserted tuple) and should never be added to the
                   * jointree.
                   *
                   * For UPDATE, we treat NEW as being another kind of reference to
                   * OLD, because it represents references to *transformed* tuples
                   * of the existing relation.  It would be wrong to enter NEW
                   * separately in the jointree, since that would cause a double
                   * join of the updated relation.  It's also wrong to fail to make
                   * a jointree entry if only NEW and not OLD is mentioned.
                   */
                  if (has_old || (has_new && stmt->event == CMD_UPDATE))
                  {
                        /*
                         * If sub_qry is a setop, manipulating its jointree will do no
                         * good at all, because the jointree is dummy. (This should be
                         * a can't-happen case because of prior tests.)
                         */
                        if (sub_qry->setOperations != NULL)
                              ereport(ERROR,
                                          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                           errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
                        /* hack so we can use addRTEtoQuery() */
                        sub_pstate->p_rtable = sub_qry->rtable;
                        sub_pstate->p_joinlist = sub_qry->jointree->fromlist;
                        addRTEtoQuery(sub_pstate, oldrte, true, false, false);
                        sub_qry->jointree->fromlist = sub_pstate->p_joinlist;
                  }

                  newactions = lappend(newactions, top_subqry);

                  free_parsestate(sub_pstate);
            }

            *actions = newactions;
      }

      free_parsestate(pstate);

      /* Close relation, but keep the exclusive lock */
      heap_close(rel, NoLock);
}


/*
 * transformAlterTableStmt -
 *          parse analysis for ALTER TABLE
 *
 * Returns a List of utility commands to be done in sequence.  One of these
 * will be the transformed AlterTableStmt, but there may be additional actions
 * to be done before and after the actual AlterTable() call.
 */
List *
transformAlterTableStmt(AlterTableStmt *stmt, const char *queryString)
{
      Relation    rel;
      ParseState *pstate;
      CreateStmtContext cxt;
      List     *result;
      List     *save_alist;
      ListCell   *lcmd,
                     *l;
      List     *newcmds = NIL;
      bool        skipValidation = true;
      AlterTableCmd *newcmd;

      /*
       * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
       * is overkill, but easy.)
       */
      stmt = (AlterTableStmt *) copyObject(stmt);

      /*
       * Acquire exclusive lock on the target relation, which will be held until
       * end of transaction.  This ensures any decisions we make here based on
       * the state of the relation will still be good at execution. We must get
       * exclusive lock now because execution will; taking a lower grade lock
       * now and trying to upgrade later risks deadlock.
       */
      rel = relation_openrv(stmt->relation, AccessExclusiveLock);

      /* Set up pstate */
      pstate = make_parsestate(NULL);
      pstate->p_sourcetext = queryString;

      cxt.stmtType = "ALTER TABLE";
      cxt.relation = stmt->relation;
      cxt.rel = rel;
      cxt.inhRelations = NIL;
      cxt.isalter = true;
      cxt.hasoids = false;          /* need not be right */
      cxt.columns = NIL;
      cxt.ckconstraints = NIL;
      cxt.fkconstraints = NIL;
      cxt.ixconstraints = NIL;
      cxt.inh_indexes = NIL;
      cxt.blist = NIL;
      cxt.alist = NIL;
      cxt.pkey = NULL;

      /*
       * The only subtypes that currently require parse transformation handling
       * are ADD COLUMN and ADD CONSTRAINT.  These largely re-use code from
       * CREATE TABLE.
       */
      foreach(lcmd, stmt->cmds)
      {
            AlterTableCmd *cmd = (AlterTableCmd *) lfirst(lcmd);

            switch (cmd->subtype)
            {
                  case AT_AddColumn:
                  case AT_AddColumnToView:
                        {
                              ColumnDef  *def = (ColumnDef *) cmd->def;

                              Assert(IsA(def, ColumnDef));
                              transformColumnDefinition(pstate, &cxt, def);

                              /*
                               * If the column has a non-null default, we can't skip
                               * validation of foreign keys.
                               */
                              if (def->raw_default != NULL)
                                    skipValidation = false;

                              /*
                               * All constraints are processed in other ways. Remove the
                               * original list
                               */
                              def->constraints = NIL;

                              newcmds = lappend(newcmds, cmd);
                              break;
                        }
                  case AT_AddConstraint:

                        /*
                         * The original AddConstraint cmd node doesn't go to newcmds
                         */
                        if (IsA(cmd->def, Constraint))
                              transformTableConstraint(pstate, &cxt,
                                                                   (Constraint *) cmd->def);
                        else if (IsA(cmd->def, FkConstraint))
                        {
                              cxt.fkconstraints = lappend(cxt.fkconstraints, cmd->def);
                              skipValidation = false;
                        }
                        else
                              elog(ERROR, "unrecognized node type: %d",
                                     (int) nodeTag(cmd->def));
                        break;

                  case AT_ProcessedConstraint:

                        /*
                         * Already-transformed ADD CONSTRAINT, so just make it look
                         * like the standard case.
                         */
                        cmd->subtype = AT_AddConstraint;
                        newcmds = lappend(newcmds, cmd);
                        break;

                  default:
                        newcmds = lappend(newcmds, cmd);
                        break;
            }
      }

      /*
       * transformIndexConstraints wants cxt.alist to contain only index
       * statements, so transfer anything we already have into save_alist
       * immediately.
       */
      save_alist = cxt.alist;
      cxt.alist = NIL;

      /* Postprocess index and FK constraints */
      transformIndexConstraints(pstate, &cxt);

      transformFKConstraints(pstate, &cxt, skipValidation, true);

      /*
       * Push any index-creation commands into the ALTER, so that they can be
       * scheduled nicely by tablecmds.c.  Note that tablecmds.c assumes that
       * the IndexStmt attached to an AT_AddIndex subcommand has already been
       * through transformIndexStmt.
       */
      foreach(l, cxt.alist)
      {
            Node     *idxstmt = (Node *) lfirst(l);

            Assert(IsA(idxstmt, IndexStmt));
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = AT_AddIndex;
            newcmd->def = (Node *) transformIndexStmt((IndexStmt *) idxstmt,
                                                                          queryString);
            newcmds = lappend(newcmds, newcmd);
      }
      cxt.alist = NIL;

      /* Append any CHECK or FK constraints to the commands list */
      foreach(l, cxt.ckconstraints)
      {
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = AT_AddConstraint;
            newcmd->def = (Node *) lfirst(l);
            newcmds = lappend(newcmds, newcmd);
      }
      foreach(l, cxt.fkconstraints)
      {
            newcmd = makeNode(AlterTableCmd);
            newcmd->subtype = AT_AddConstraint;
            newcmd->def = (Node *) lfirst(l);
            newcmds = lappend(newcmds, newcmd);
      }

      /* Close rel but keep lock */
      relation_close(rel, NoLock);

      /*
       * Output results.
       */
      stmt->cmds = newcmds;

      result = lappend(cxt.blist, stmt);
      result = list_concat(result, cxt.alist);
      result = list_concat(result, save_alist);

      return result;
}


/*
 * Preprocess a list of column constraint clauses
 * to attach constraint attributes to their primary constraint nodes
 * and detect inconsistent/misplaced constraint attributes.
 *
 * NOTE: currently, attributes are only supported for FOREIGN KEY primary
 * constraints, but someday they ought to be supported for other constraints.
 */
static void
transformConstraintAttrs(List *constraintList)
{
      Node     *lastprimarynode = NULL;
      bool        saw_deferrability = false;
      bool        saw_initially = false;
      ListCell   *clist;

      foreach(clist, constraintList)
      {
            Node     *node = lfirst(clist);

            if (!IsA(node, Constraint))
            {
                  lastprimarynode = node;
                  /* reset flags for new primary node */
                  saw_deferrability = false;
                  saw_initially = false;
            }
            else
            {
                  Constraint *con = (Constraint *) node;

                  switch (con->contype)
                  {
                        case CONSTR_ATTR_DEFERRABLE:
                              if (lastprimarynode == NULL ||
                                    !IsA(lastprimarynode, FkConstraint))
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("misplaced DEFERRABLE clause")));
                              if (saw_deferrability)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
                              saw_deferrability = true;
                              ((FkConstraint *) lastprimarynode)->deferrable = true;
                              break;
                        case CONSTR_ATTR_NOT_DEFERRABLE:
                              if (lastprimarynode == NULL ||
                                    !IsA(lastprimarynode, FkConstraint))
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("misplaced NOT DEFERRABLE clause")));
                              if (saw_deferrability)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("multiple DEFERRABLE/NOT DEFERRABLE clauses not allowed")));
                              saw_deferrability = true;
                              ((FkConstraint *) lastprimarynode)->deferrable = false;
                              if (saw_initially &&
                                    ((FkConstraint *) lastprimarynode)->initdeferred)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
                              break;
                        case CONSTR_ATTR_DEFERRED:
                              if (lastprimarynode == NULL ||
                                    !IsA(lastprimarynode, FkConstraint))
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                           errmsg("misplaced INITIALLY DEFERRED clause")));
                              if (saw_initially)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
                              saw_initially = true;
                              ((FkConstraint *) lastprimarynode)->initdeferred = true;

                              /*
                               * If only INITIALLY DEFERRED appears, assume DEFERRABLE
                               */
                              if (!saw_deferrability)
                                    ((FkConstraint *) lastprimarynode)->deferrable = true;
                              else if (!((FkConstraint *) lastprimarynode)->deferrable)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE")));
                              break;
                        case CONSTR_ATTR_IMMEDIATE:
                              if (lastprimarynode == NULL ||
                                    !IsA(lastprimarynode, FkConstraint))
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                          errmsg("misplaced INITIALLY IMMEDIATE clause")));
                              if (saw_initially)
                                    ereport(ERROR,
                                                (errcode(ERRCODE_SYNTAX_ERROR),
                                                 errmsg("multiple INITIALLY IMMEDIATE/DEFERRED clauses not allowed")));
                              saw_initially = true;
                              ((FkConstraint *) lastprimarynode)->initdeferred = false;
                              break;
                        default:
                              /* Otherwise it's not an attribute */
                              lastprimarynode = node;
                              /* reset flags for new primary node */
                              saw_deferrability = false;
                              saw_initially = false;
                              break;
                  }
            }
      }
}

/*
 * Special handling of type definition for a column
 */
static void
transformColumnType(ParseState *pstate, ColumnDef *column)
{
      /*
       * All we really need to do here is verify that the type is valid.
       */
      Type        ctype = typenameType(pstate, column->typename, NULL);

      ReleaseSysCache(ctype);
}


/*
 * transformCreateSchemaStmt -
 *      analyzes the CREATE SCHEMA statement
 *
 * Split the schema element list into individual commands and place
 * them in the result list in an order such that there are no forward
 * references (e.g. GRANT to a table created later in the list). Note
 * that the logic we use for determining forward references is
 * presently quite incomplete.
 *
 * SQL92 also allows constraints to make forward references, so thumb through
 * the table columns and move forward references to a posterior alter-table
 * command.
 *
 * The result is a list of parse nodes that still need to be analyzed ---
 * but we can't analyze the later commands until we've executed the earlier
 * ones, because of possible inter-object references.
 *
 * Note: this breaks the rules a little bit by modifying schema-name fields
 * within passed-in structs.  However, the transformation would be the same
 * if done over, so it should be all right to scribble on the input to this
 * extent.
 */
List *
transformCreateSchemaStmt(CreateSchemaStmt *stmt)
{
      CreateSchemaStmtContext cxt;
      List     *result;
      ListCell   *elements;

      cxt.stmtType = "CREATE SCHEMA";
      cxt.schemaname = stmt->schemaname;
      cxt.authid = stmt->authid;
      cxt.sequences = NIL;
      cxt.tables = NIL;
      cxt.views = NIL;
      cxt.indexes = NIL;
      cxt.triggers = NIL;
      cxt.grants = NIL;

      /*
       * Run through each schema element in the schema element list. Separate
       * statements by type, and do preliminary analysis.
       */
      foreach(elements, stmt->schemaElts)
      {
            Node     *element = lfirst(elements);

            switch (nodeTag(element))
            {
                  case T_CreateSeqStmt:
                        {
                              CreateSeqStmt *elp = (CreateSeqStmt *) element;

                              setSchemaName(cxt.schemaname, &elp->sequence->schemaname);
                              cxt.sequences = lappend(cxt.sequences, element);
                        }
                        break;

                  case T_CreateStmt:
                        {
                              CreateStmt *elp = (CreateStmt *) element;

                              setSchemaName(cxt.schemaname, &elp->relation->schemaname);

                              /*
                               * XXX todo: deal with constraints
                               */
                              cxt.tables = lappend(cxt.tables, element);
                        }
                        break;

                  case T_ViewStmt:
                        {
                              ViewStmt   *elp = (ViewStmt *) element;

                              setSchemaName(cxt.schemaname, &elp->view->schemaname);

                              /*
                               * XXX todo: deal with references between views
                               */
                              cxt.views = lappend(cxt.views, element);
                        }
                        break;

                  case T_IndexStmt:
                        {
                              IndexStmt  *elp = (IndexStmt *) element;

                              setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                              cxt.indexes = lappend(cxt.indexes, element);
                        }
                        break;

                  case T_CreateTrigStmt:
                        {
                              CreateTrigStmt *elp = (CreateTrigStmt *) element;

                              setSchemaName(cxt.schemaname, &elp->relation->schemaname);
                              cxt.triggers = lappend(cxt.triggers, element);
                        }
                        break;

                  case T_GrantStmt:
                        cxt.grants = lappend(cxt.grants, element);
                        break;

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

      result = NIL;
      result = list_concat(result, cxt.sequences);
      result = list_concat(result, cxt.tables);
      result = list_concat(result, cxt.views);
      result = list_concat(result, cxt.indexes);
      result = list_concat(result, cxt.triggers);
      result = list_concat(result, cxt.grants);

      return result;
}

/*
 * setSchemaName
 *          Set or check schema name in an element of a CREATE SCHEMA command
 */
static void
setSchemaName(char *context_schema, char **stmt_schema_name)
{
      if (*stmt_schema_name == NULL)
            *stmt_schema_name = context_schema;
      else if (strcmp(context_schema, *stmt_schema_name) != 0)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_SCHEMA_DEFINITION),
                         errmsg("CREATE specifies a schema (%s) "
                                    "different from the one being created (%s)",
                                    *stmt_schema_name, context_schema)));
}

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