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

rewriteDefine.c

/*-------------------------------------------------------------------------
 *
 * rewriteDefine.c
 *      routines for defining a rewrite rule
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/rewrite/rewriteDefine.c,v 1.138 2009/06/11 14:49:01 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/heapam.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_rewrite.h"
#include "catalog/storage.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "parser/parse_utilcmd.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rewriteSupport.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tqual.h"


static void checkRuleResultList(List *targetList, TupleDesc resultDesc,
                              bool isSelect);
static bool setRuleCheckAsUser_walker(Node *node, Oid *context);
static void setRuleCheckAsUser_Query(Query *qry, Oid userid);


/*
 * InsertRule -
 *      takes the arguments and inserts them as a row into the system
 *      relation "pg_rewrite"
 */
static Oid
InsertRule(char *rulname,
               int evtype,
               Oid eventrel_oid,
               AttrNumber evslot_index,
               bool evinstead,
               Node *event_qual,
               List *action,
               bool replace)
{
      char     *evqual = nodeToString(event_qual);
      char     *actiontree = nodeToString((Node *) action);
      int               i;
      Datum       values[Natts_pg_rewrite];
      bool        nulls[Natts_pg_rewrite];
      bool        replaces[Natts_pg_rewrite];
      NameData    rname;
      Relation    pg_rewrite_desc;
      HeapTuple   tup,
                        oldtup;
      Oid               rewriteObjectId;
      ObjectAddress myself,
                        referenced;
      bool        is_update = false;

      /*
       * Set up *nulls and *values arrays
       */
      MemSet(nulls, false, sizeof(nulls));

      i = 0;
      namestrcpy(&rname, rulname);
      values[i++] = NameGetDatum(&rname); /* rulename */
      values[i++] = ObjectIdGetDatum(eventrel_oid);         /* ev_class */
      values[i++] = Int16GetDatum(evslot_index);      /* ev_attr */
      values[i++] = CharGetDatum(evtype + '0'); /* ev_type */
      values[i++] = CharGetDatum(RULE_FIRES_ON_ORIGIN);     /* ev_enabled */
      values[i++] = BoolGetDatum(evinstead);          /* is_instead */
      values[i++] = CStringGetTextDatum(evqual);      /* ev_qual */
      values[i++] = CStringGetTextDatum(actiontree);        /* ev_action */

      /*
       * Ready to store new pg_rewrite tuple
       */
      pg_rewrite_desc = heap_open(RewriteRelationId, RowExclusiveLock);

      /*
       * Check to see if we are replacing an existing tuple
       */
      oldtup = SearchSysCache(RULERELNAME,
                                          ObjectIdGetDatum(eventrel_oid),
                                          PointerGetDatum(rulname),
                                          0, 0);

      if (HeapTupleIsValid(oldtup))
      {
            if (!replace)
                  ereport(ERROR,
                              (errcode(ERRCODE_DUPLICATE_OBJECT),
                               errmsg("rule \"%s\" for relation \"%s\" already exists",
                                          rulname, get_rel_name(eventrel_oid))));

            /*
             * When replacing, we don't need to replace every attribute
             */
            MemSet(replaces, false, sizeof(replaces));
            replaces[Anum_pg_rewrite_ev_attr - 1] = true;
            replaces[Anum_pg_rewrite_ev_type - 1] = true;
            replaces[Anum_pg_rewrite_is_instead - 1] = true;
            replaces[Anum_pg_rewrite_ev_qual - 1] = true;
            replaces[Anum_pg_rewrite_ev_action - 1] = true;

            tup = heap_modify_tuple(oldtup, RelationGetDescr(pg_rewrite_desc),
                                                values, nulls, replaces);

            simple_heap_update(pg_rewrite_desc, &tup->t_self, tup);

            ReleaseSysCache(oldtup);

            rewriteObjectId = HeapTupleGetOid(tup);
            is_update = true;
      }
      else
      {
            tup = heap_form_tuple(pg_rewrite_desc->rd_att, values, nulls);

            rewriteObjectId = simple_heap_insert(pg_rewrite_desc, tup);
      }

      /* Need to update indexes in either case */
      CatalogUpdateIndexes(pg_rewrite_desc, tup);

      heap_freetuple(tup);

      /* If replacing, get rid of old dependencies and make new ones */
      if (is_update)
            deleteDependencyRecordsFor(RewriteRelationId, rewriteObjectId);

      /*
       * Install dependency on rule's relation to ensure it will go away on
       * relation deletion.  If the rule is ON SELECT, make the dependency
       * implicit --- this prevents deleting a view's SELECT rule.  Other kinds
       * of rules can be AUTO.
       */
      myself.classId = RewriteRelationId;
      myself.objectId = rewriteObjectId;
      myself.objectSubId = 0;

      referenced.classId = RelationRelationId;
      referenced.objectId = eventrel_oid;
      referenced.objectSubId = 0;

      recordDependencyOn(&myself, &referenced,
                   (evtype == CMD_SELECT) ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO);

      /*
       * Also install dependencies on objects referenced in action and qual.
       */
      recordDependencyOnExpr(&myself, (Node *) action, NIL,
                                       DEPENDENCY_NORMAL);

      if (event_qual != NULL)
      {
            /* Find query containing OLD/NEW rtable entries */
            Query    *qry = (Query *) linitial(action);

            qry = getInsertSelectQuery(qry, NULL);
            recordDependencyOnExpr(&myself, event_qual, qry->rtable,
                                             DEPENDENCY_NORMAL);
      }

      heap_close(pg_rewrite_desc, RowExclusiveLock);

      return rewriteObjectId;
}

/*
 * DefineRule
 *          Execute a CREATE RULE command.
 */
void
DefineRule(RuleStmt *stmt, const char *queryString)
{
      List     *actions;
      Node     *whereClause;
      Oid               relId;

      /* Parse analysis ... */
      transformRuleStmt(stmt, queryString, &actions, &whereClause);

      /* ... find the relation ... */
      relId = RangeVarGetRelid(stmt->relation, false);

      /* ... and execute */
      DefineQueryRewrite(stmt->rulename,
                                 relId,
                                 whereClause,
                                 stmt->event,
                                 stmt->instead,
                                 stmt->replace,
                                 actions);
}


/*
 * DefineQueryRewrite
 *          Create a rule
 *
 * This is essentially the same as DefineRule() except that the rule's
 * action and qual have already been passed through parse analysis.
 */
void
DefineQueryRewrite(char *rulename,
                           Oid event_relid,
                           Node *event_qual,
                           CmdType event_type,
                           bool is_instead,
                           bool replace,
                           List *action)
{
      Relation    event_relation;
      Oid               ruleId;
      int               event_attno;
      ListCell   *l;
      Query    *query;
      bool        RelisBecomingView = false;

      /*
       * If we are installing an ON SELECT rule, we had better grab
       * AccessExclusiveLock to ensure no SELECTs are currently running on the
       * event relation.      For other types of rules, it might be sufficient to
       * grab ShareLock to lock out insert/update/delete actions.  But for now,
       * let's just grab AccessExclusiveLock all the time.
       */
      event_relation = heap_open(event_relid, AccessExclusiveLock);

      /*
       * Verify relation is of a type that rules can sensibly be applied to.
       */
      if (event_relation->rd_rel->relkind != RELKIND_RELATION &&
            event_relation->rd_rel->relkind != RELKIND_VIEW)
            ereport(ERROR,
                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                         errmsg("\"%s\" is not a table or view",
                                    RelationGetRelationName(event_relation))));

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

      /*
       * Check user has permission to apply rules to this relation.
       */
      if (!pg_class_ownercheck(event_relid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 RelationGetRelationName(event_relation));

      /*
       * No rule actions that modify OLD or NEW
       */
      foreach(l, action)
      {
            query = (Query *) lfirst(l);
            if (query->resultRelation == 0)
                  continue;
            /* Don't be fooled by INSERT/SELECT */
            if (query != getInsertSelectQuery(query, NULL))
                  continue;
            if (query->resultRelation == PRS2_OLD_VARNO)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("rule actions on OLD are not implemented"),
                               errhint("Use views or triggers instead.")));
            if (query->resultRelation == PRS2_NEW_VARNO)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("rule actions on NEW are not implemented"),
                               errhint("Use triggers instead.")));
      }

      if (event_type == CMD_SELECT)
      {
            /*
             * Rules ON SELECT are restricted to view definitions
             *
             * So there cannot be INSTEAD NOTHING, ...
             */
            if (list_length(action) == 0)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("INSTEAD NOTHING rules on SELECT are not implemented"),
                               errhint("Use views instead.")));

            /*
             * ... there cannot be multiple actions, ...
             */
            if (list_length(action) > 1)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("multiple actions for rules on SELECT are not implemented")));

            /*
             * ... the one action must be a SELECT, ...
             */
            query = (Query *) linitial(action);
            if (!is_instead ||
                  query->commandType != CMD_SELECT ||
                  query->utilityStmt != NULL ||
                  query->intoClause != NULL)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("rules on SELECT must have action INSTEAD SELECT")));

            /*
             * ... there can be no rule qual, ...
             */
            if (event_qual != NULL)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("event qualifications are not implemented for rules on SELECT")));

            /*
             * ... the targetlist of the SELECT action must exactly match the
             * event relation, ...
             */
            checkRuleResultList(query->targetList,
                                          RelationGetDescr(event_relation),
                                          true);

            /*
             * ... there must not be another ON SELECT rule already ...
             */
            if (!replace && event_relation->rd_rules != NULL)
            {
                  int               i;

                  for (i = 0; i < event_relation->rd_rules->numLocks; i++)
                  {
                        RewriteRule *rule;

                        rule = event_relation->rd_rules->rules[i];
                        if (rule->event == CMD_SELECT)
                              ereport(ERROR,
                                      (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                       errmsg("\"%s\" is already a view",
                                                  RelationGetRelationName(event_relation))));
                  }
            }

            /*
             * ... and finally the rule must be named _RETURN.
             */
            if (strcmp(rulename, ViewSelectRuleName) != 0)
            {
                  /*
                   * In versions before 7.3, the expected name was _RETviewname. For
                   * backwards compatibility with old pg_dump output, accept that
                   * and silently change it to _RETURN.  Since this is just a quick
                   * backwards-compatibility hack, limit the number of characters
                   * checked to a few less than NAMEDATALEN; this saves having to
                   * worry about where a multibyte character might have gotten
                   * truncated.
                   */
                  if (strncmp(rulename, "_RET", 4) != 0 ||
                        strncmp(rulename + 4, RelationGetRelationName(event_relation),
                                    NAMEDATALEN - 4 - 4) != 0)
                        ereport(ERROR,
                                    (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                                     errmsg("view rule for \"%s\" must be named \"%s\"",
                                                RelationGetRelationName(event_relation),
                                                ViewSelectRuleName)));
                  rulename = pstrdup(ViewSelectRuleName);
            }

            /*
             * Are we converting a relation to a view?
             *
             * If so, check that the relation is empty because the storage for the
             * relation is going to be deleted.  Also insist that the rel not have
             * any triggers, indexes, or child tables.      (Note: these tests are too
             * strict, because they will reject relations that once had such but
             * don't anymore.  But we don't really care, because this whole
             * business of converting relations to views is just a kluge to allow
             * loading ancient pg_dump files.)
             */
            if (event_relation->rd_rel->relkind != RELKIND_VIEW)
            {
                  HeapScanDesc scanDesc;

                  scanDesc = heap_beginscan(event_relation, SnapshotNow, 0, NULL);
                  if (heap_getnext(scanDesc, ForwardScanDirection) != NULL)
                        ereport(ERROR,
                                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                     errmsg("could not convert table \"%s\" to a view because it is not empty",
                                                RelationGetRelationName(event_relation))));
                  heap_endscan(scanDesc);

                  if (event_relation->rd_rel->relhastriggers)
                        ereport(ERROR,
                                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                     errmsg("could not convert table \"%s\" to a view because it has triggers",
                                                RelationGetRelationName(event_relation)),
                                     errhint("In particular, the table cannot be involved in any foreign key relationships.")));

                  if (event_relation->rd_rel->relhasindex)
                        ereport(ERROR,
                                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                     errmsg("could not convert table \"%s\" to a view because it has indexes",
                                                RelationGetRelationName(event_relation))));

                  if (event_relation->rd_rel->relhassubclass)
                        ereport(ERROR,
                                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                     errmsg("could not convert table \"%s\" to a view because it has child tables",
                                                RelationGetRelationName(event_relation))));

                  RelisBecomingView = true;
            }
      }
      else
      {
            /*
             * For non-SELECT rules, a RETURNING list can appear in at most one of
             * the actions ... and there can't be any RETURNING list at all in a
             * conditional or non-INSTEAD rule.  (Actually, there can be at most
             * one RETURNING list across all rules on the same event, but it seems
             * best to enforce that at rule expansion time.)  If there is a
             * RETURNING list, it must match the event relation.
             */
            bool        haveReturning = false;

            foreach(l, action)
            {
                  query = (Query *) lfirst(l);

                  if (!query->returningList)
                        continue;
                  if (haveReturning)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                          errmsg("cannot have multiple RETURNING lists in a rule")));
                  haveReturning = true;
                  if (event_qual != NULL)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("RETURNING lists are not supported in conditional rules")));
                  if (!is_instead)
                        ereport(ERROR,
                                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                     errmsg("RETURNING lists are not supported in non-INSTEAD rules")));
                  checkRuleResultList(query->returningList,
                                                RelationGetDescr(event_relation),
                                                false);
            }
      }

      /*
       * This rule is allowed - prepare to install it.
       */
      event_attno = -1;

      /* discard rule if it's null action and not INSTEAD; it's a no-op */
      if (action != NIL || is_instead)
      {
            ruleId = InsertRule(rulename,
                                          event_type,
                                          event_relid,
                                          event_attno,
                                          is_instead,
                                          event_qual,
                                          action,
                                          replace);

            /*
             * Set pg_class 'relhasrules' field TRUE for event relation. If
             * appropriate, also modify the 'relkind' field to show that the
             * relation is now a view.
             *
             * Important side effect: an SI notice is broadcast to force all
             * backends (including me!) to update relcache entries with the new
             * rule.
             */
            SetRelationRuleStatus(event_relid, true, RelisBecomingView);
      }

      /*
       * IF the relation is becoming a view, delete the storage files associated
       * with it.  NB: we had better have AccessExclusiveLock to do this ...
       *
       * XXX what about getting rid of its TOAST table?  For now, we don't.
       */
      if (RelisBecomingView)
            RelationDropStorage(event_relation);

      /* Close rel, but keep lock till commit... */
      heap_close(event_relation, NoLock);
}

/*
 * checkRuleResultList
 *          Verify that targetList produces output compatible with a tupledesc
 *
 * The targetList might be either a SELECT targetlist, or a RETURNING list;
 * isSelect tells which.  (This is mostly used for choosing error messages,
 * but also we don't enforce column name matching for RETURNING.)
 */
static void
checkRuleResultList(List *targetList, TupleDesc resultDesc, bool isSelect)
{
      ListCell   *tllist;
      int               i;

      i = 0;
      foreach(tllist, targetList)
      {
            TargetEntry *tle = (TargetEntry *) lfirst(tllist);
            int32       tletypmod;
            Form_pg_attribute attr;
            char     *attname;

            /* resjunk entries may be ignored */
            if (tle->resjunk)
                  continue;
            i++;
            if (i > resultDesc->natts)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                               isSelect ?
                           errmsg("SELECT rule's target list has too many entries") :
                               errmsg("RETURNING list has too many entries")));

            attr = resultDesc->attrs[i - 1];
            attname = NameStr(attr->attname);

            /*
             * Disallow dropped columns in the relation.  This won't happen in the
             * cases we actually care about (namely creating a view via CREATE
             * TABLE then CREATE RULE, or adding a RETURNING rule to a view).
             * Trying to cope with it is much more trouble than it's worth,
             * because we'd have to modify the rule to insert dummy NULLs at the
             * right positions.
             */
            if (attr->attisdropped)
                  ereport(ERROR,
                              (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                               errmsg("cannot convert relation containing dropped columns to view")));

            if (isSelect && strcmp(tle->resname, attname) != 0)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                               errmsg("SELECT rule's target entry %d has different column name from \"%s\"", i, attname)));

            if (attr->atttypid != exprType((Node *) tle->expr))
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                               isSelect ?
                               errmsg("SELECT rule's target entry %d has different type from column \"%s\"",
                                          i, attname) :
                               errmsg("RETURNING list's entry %d has different type from column \"%s\"",
                                          i, attname)));

            /*
             * Allow typmods to be different only if one of them is -1, ie,
             * "unspecified".  This is necessary for cases like "numeric", where
             * the table will have a filled-in default length but the select
             * rule's expression will probably have typmod = -1.
             */
            tletypmod = exprTypmod((Node *) tle->expr);
            if (attr->atttypmod != tletypmod &&
                  attr->atttypmod != -1 && tletypmod != -1)
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                               isSelect ?
                               errmsg("SELECT rule's target entry %d has different size from column \"%s\"",
                                          i, attname) :
                               errmsg("RETURNING list's entry %d has different size from column \"%s\"",
                                          i, attname)));
      }

      if (i != resultDesc->natts)
            ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         isSelect ?
                         errmsg("SELECT rule's target list has too few entries") :
                         errmsg("RETURNING list has too few entries")));
}

/*
 * setRuleCheckAsUser
 *          Recursively scan a query or expression tree and set the checkAsUser
 *          field to the given userid in all rtable entries.
 *
 * Note: for a view (ON SELECT rule), the checkAsUser field of the *OLD*
 * RTE entry will be overridden when the view rule is expanded, and the
 * checkAsUser field of the *NEW* entry is irrelevant because that entry's
 * requiredPerms bits will always be zero.      However, for other types of rules
 * it's important to set these fields to match the rule owner.  So we just set
 * them always.
 */
void
setRuleCheckAsUser(Node *node, Oid userid)
{
      (void) setRuleCheckAsUser_walker(node, &userid);
}

static bool
setRuleCheckAsUser_walker(Node *node, Oid *context)
{
      if (node == NULL)
            return false;
      if (IsA(node, Query))
      {
            setRuleCheckAsUser_Query((Query *) node, *context);
            return false;
      }
      return expression_tree_walker(node, setRuleCheckAsUser_walker,
                                                  (void *) context);
}

static void
setRuleCheckAsUser_Query(Query *qry, Oid userid)
{
      ListCell   *l;

      /* Set all the RTEs in this query node */
      foreach(l, qry->rtable)
      {
            RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);

            if (rte->rtekind == RTE_SUBQUERY)
            {
                  /* Recurse into subquery in FROM */
                  setRuleCheckAsUser_Query(rte->subquery, userid);
            }
            else
                  rte->checkAsUser = userid;
      }

      /* Recurse into subquery-in-WITH */
      foreach(l, qry->cteList)
      {
            CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);

            setRuleCheckAsUser_Query((Query *) cte->ctequery, userid);
      }

      /* If there are sublinks, search for them and process their RTEs */
      if (qry->hasSubLinks)
            query_tree_walker(qry, setRuleCheckAsUser_walker, (void *) &userid,
                                      QTW_IGNORE_RC_SUBQUERIES);
}


/*
 * Change the firing semantics of an existing rule.
 */
void
EnableDisableRule(Relation rel, const char *rulename,
                          char fires_when)
{
      Relation    pg_rewrite_desc;
      Oid               owningRel = RelationGetRelid(rel);
      Oid               eventRelationOid;
      HeapTuple   ruletup;
      bool        changed = false;

      /*
       * Find the rule tuple to change.
       */
      pg_rewrite_desc = heap_open(RewriteRelationId, RowExclusiveLock);
      ruletup = SearchSysCacheCopy(RULERELNAME,
                                                 ObjectIdGetDatum(owningRel),
                                                 PointerGetDatum(rulename),
                                                 0, 0);
      if (!HeapTupleIsValid(ruletup))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("rule \"%s\" for relation \"%s\" does not exist",
                                    rulename, get_rel_name(owningRel))));

      /*
       * Verify that the user has appropriate permissions.
       */
      eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_class;
      Assert(eventRelationOid == owningRel);
      if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
            aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
                                 get_rel_name(eventRelationOid));

      /*
       * Change ev_enabled if it is different from the desired new state.
       */
      if (DatumGetChar(((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_enabled) !=
            fires_when)
      {
            ((Form_pg_rewrite) GETSTRUCT(ruletup))->ev_enabled =
                  CharGetDatum(fires_when);
            simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup);

            /* keep system catalog indexes current */
            CatalogUpdateIndexes(pg_rewrite_desc, ruletup);

            changed = true;
      }

      heap_freetuple(ruletup);
      heap_close(pg_rewrite_desc, RowExclusiveLock);

      /*
       * If we changed anything, broadcast a SI inval message to force each
       * backend (including our own!) to rebuild relation's relcache entry.
       * Otherwise they will fail to apply the change promptly.
       */
      if (changed)
            CacheInvalidateRelcache(rel);
}


/*
 * Rename an existing rewrite rule.
 *
 * This is unused code at the moment.  Note that it lacks a permissions check.
 */
#ifdef NOT_USED
void
RenameRewriteRule(Oid owningRel, const char *oldName,
                          const char *newName)
{
      Relation    pg_rewrite_desc;
      HeapTuple   ruletup;

      pg_rewrite_desc = heap_open(RewriteRelationId, RowExclusiveLock);

      ruletup = SearchSysCacheCopy(RULERELNAME,
                                                 ObjectIdGetDatum(owningRel),
                                                 PointerGetDatum(oldName),
                                                 0, 0);
      if (!HeapTupleIsValid(ruletup))
            ereport(ERROR,
                        (errcode(ERRCODE_UNDEFINED_OBJECT),
                         errmsg("rule \"%s\" for relation \"%s\" does not exist",
                                    oldName, get_rel_name(owningRel))));

      /* should not already exist */
      if (IsDefinedRewriteRule(owningRel, newName))
            ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_OBJECT),
                         errmsg("rule \"%s\" for relation \"%s\" already exists",
                                    newName, get_rel_name(owningRel))));

      namestrcpy(&(((Form_pg_rewrite) GETSTRUCT(ruletup))->rulename), newName);

      simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup);

      /* keep system catalog indexes current */
      CatalogUpdateIndexes(pg_rewrite_desc, ruletup);

      heap_freetuple(ruletup);
      heap_close(pg_rewrite_desc, RowExclusiveLock);
}

#endif

Generated by  Doxygen 1.6.0   Back to index