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rewriteRemove.c

/*-------------------------------------------------------------------------
 *
 * rewriteRemove.c
 *      routines for removing rewrite rules
 *
 * 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/rewriteRemove.c,v 1.78 2009/06/11 14:49:01 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/heapam.h"
#include "access/sysattr.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/pg_rewrite.h"
#include "miscadmin.h"
#include "rewrite/rewriteRemove.h"
#include "utils/acl.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tqual.h"


/*
 * RemoveRewriteRule
 *
 * Delete a rule given its name.
 */
void
RemoveRewriteRule(Oid owningRel, const char *ruleName, DropBehavior behavior,
                          bool missing_ok)
{
      HeapTuple   tuple;
      Oid               eventRelationOid;
      ObjectAddress object;

      /*
       * Find the tuple for the target rule.
       */
      tuple = SearchSysCache(RULERELNAME,
                                       ObjectIdGetDatum(owningRel),
                                       PointerGetDatum(ruleName),
                                       0, 0);

      /*
       * complain if no rule with such name exists
       */
      if (!HeapTupleIsValid(tuple))
      {
            if (!missing_ok)
                  ereport(ERROR,
                              (errcode(ERRCODE_UNDEFINED_OBJECT),
                               errmsg("rule \"%s\" for relation \"%s\" does not exist",
                                          ruleName, get_rel_name(owningRel))));
            else
                  ereport(NOTICE,
                              (errmsg("rule \"%s\" for relation \"%s\" does not exist, skipping",
                                          ruleName, get_rel_name(owningRel))));
            return;
      }

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

      /*
       * Do the deletion
       */
      object.classId = RewriteRelationId;
      object.objectId = HeapTupleGetOid(tuple);
      object.objectSubId = 0;

      ReleaseSysCache(tuple);

      performDeletion(&object, behavior);
}


/*
 * Guts of rule deletion.
 */
void
RemoveRewriteRuleById(Oid ruleOid)
{
      Relation    RewriteRelation;
      ScanKeyData skey[1];
      SysScanDesc rcscan;
      Relation    event_relation;
      HeapTuple   tuple;
      Oid               eventRelationOid;

      /*
       * Open the pg_rewrite relation.
       */
      RewriteRelation = heap_open(RewriteRelationId, RowExclusiveLock);

      /*
       * Find the tuple for the target rule.
       */
      ScanKeyInit(&skey[0],
                        ObjectIdAttributeNumber,
                        BTEqualStrategyNumber, F_OIDEQ,
                        ObjectIdGetDatum(ruleOid));

      rcscan = systable_beginscan(RewriteRelation, RewriteOidIndexId, true,
                                                SnapshotNow, 1, skey);

      tuple = systable_getnext(rcscan);

      if (!HeapTupleIsValid(tuple))
            elog(ERROR, "could not find tuple for rule %u", ruleOid);

      /*
       * We had better grab AccessExclusiveLock to ensure that no queries are
       * going on that might depend on this rule.  (Note: a weaker lock would
       * suffice if it's not an ON SELECT rule.)
       */
      eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
      event_relation = heap_open(eventRelationOid, AccessExclusiveLock);

      /*
       * Now delete the pg_rewrite tuple for the rule
       */
      simple_heap_delete(RewriteRelation, &tuple->t_self);

      systable_endscan(rcscan);

      heap_close(RewriteRelation, RowExclusiveLock);

      /*
       * Issue shared-inval notice to force all backends (including me!) to
       * update relcache entries with the new rule set.
       */
      CacheInvalidateRelcache(event_relation);

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

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