src/backend/rewrite/rewriteRemove.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteRemove.c
   4  *        routines for removing rewrite rules
   5  *
   6  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL: pgsql/src/backend/rewrite/rewriteRemove.c,v 1.68 2006/10/04 00:29:56 momjian Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/genam.h"
  18 #include "access/heapam.h"
  19 #include "catalog/dependency.h"
  20 #include "catalog/indexing.h"
  21 #include "catalog/pg_rewrite.h"
  22 #include "miscadmin.h"
  23 #include "rewrite/rewriteRemove.h"
  24 #include "rewrite/rewriteSupport.h"
  25 #include "utils/acl.h"
  26 #include "utils/fmgroids.h"
  27 #include "utils/lsyscache.h"
  28 #include "utils/syscache.h"
  29
  30
  31 /*
  32  * RemoveRewriteRule
  33  *
  34  * Delete a rule given its name.
  35  */
  36 void
  37 RemoveRewriteRule(Oid owningRel, const char *ruleName, DropBehavior behavior,
  38                                   bool missing_ok)
  39 {
  40         HeapTuple       tuple;
  41         Oid                     eventRelationOid;
  42         ObjectAddress object;
  43
  44         /*
  45          * Find the tuple for the target rule.
  46          */
  47         tuple = SearchSysCache(RULERELNAME,
  48                                                    ObjectIdGetDatum(owningRel),
  49                                                    PointerGetDatum(ruleName),
  50                                                    0, 0);
  51
  52         /*
  53          * complain if no rule with such name exists
  54          */
  55         if (!HeapTupleIsValid(tuple))
  56         {
  57                 if (!missing_ok)
  58                         ereport(ERROR,
  59                                         (errcode(ERRCODE_UNDEFINED_OBJECT),
  60                                          errmsg("rule \"%s\" for relation \"%s\" does not exist",
  61                                                         ruleName, get_rel_name(owningRel))));
  62                 else
  63                         ereport(NOTICE,
  64                                         (errmsg("rule \"%s\" for relation \"%s\" does not exist, skipping",
  65                                                         ruleName, get_rel_name(owningRel))));
  66                 return;
  67         }
  68
  69         /*
  70          * Verify user has appropriate permissions.
  71          */
  72         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
  73         Assert(eventRelationOid == owningRel);
  74         if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
  75                 aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
  76                                            get_rel_name(eventRelationOid));
  77
  78         /*
  79          * Do the deletion
  80          */
  81         object.classId = RewriteRelationId;
  82         object.objectId = HeapTupleGetOid(tuple);
  83         object.objectSubId = 0;
  84
  85         ReleaseSysCache(tuple);
  86
  87         performDeletion(&object, behavior);
  88 }
  89
  90
  91 /*
  92  * Guts of rule deletion.
  93  */
  94 void
  95 RemoveRewriteRuleById(Oid ruleOid)
  96 {
  97         Relation        RewriteRelation;
  98         ScanKeyData skey[1];
  99         SysScanDesc rcscan;
 100         Relation        event_relation;
 101         HeapTuple       tuple;
 102         Oid                     eventRelationOid;
 103         bool            hasMoreRules;
 104
 105         /*
 106          * Open the pg_rewrite relation.
 107          */
 108         RewriteRelation = heap_open(RewriteRelationId, RowExclusiveLock);
 109
 110         /*
 111          * Find the tuple for the target rule.
 112          */
 113         ScanKeyInit(&skey[0],
 114                                 ObjectIdAttributeNumber,
 115                                 BTEqualStrategyNumber, F_OIDEQ,
 116                                 ObjectIdGetDatum(ruleOid));
 117
 118         rcscan = systable_beginscan(RewriteRelation, RewriteOidIndexId, true,
 119                                                                 SnapshotNow, 1, skey);
 120
 121         tuple = systable_getnext(rcscan);
 122
 123         if (!HeapTupleIsValid(tuple))
 124                 elog(ERROR, "could not find tuple for rule %u", ruleOid);
 125
 126         /*
 127          * We had better grab AccessExclusiveLock so that we know no other rule
 128          * additions/deletions are going on for this relation.  Else we cannot set
 129          * relhasrules correctly.  Besides, we don't want to be changing the
 130          * ruleset while queries are executing on the rel.
 131          */
 132         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
 133         event_relation = heap_open(eventRelationOid, AccessExclusiveLock);
 134
 135         hasMoreRules = event_relation->rd_rules != NULL &&
 136                 event_relation->rd_rules->numLocks > 1;
 137
 138         /*
 139          * Now delete the pg_rewrite tuple for the rule
 140          */
 141         simple_heap_delete(RewriteRelation, &tuple->t_self);
 142
 143         systable_endscan(rcscan);
 144
 145         heap_close(RewriteRelation, RowExclusiveLock);
 146
 147         /*
 148          * Set pg_class 'relhasrules' field correctly for event relation.
 149          *
 150          * Important side effect: an SI notice is broadcast to force all backends
 151          * (including me!) to update relcache entries with the new rule set.
 152          * Therefore, must do this even if relhasrules is still true!
 153          */
 154         SetRelationRuleStatus(eventRelationOid, hasMoreRules, false);
 155
 156         /* Close rel, but keep lock till commit... */
 157         heap_close(event_relation, NoLock);
 158 }