src/backend/rewrite/rewriteRemove.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteRemove.c
   4  *        routines for removing rewrite rules
   5  *
   6  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteRemove.c,v 1.52 2002/07/20 05:16:58 momjian Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/genam.h"
  18 #include "access/heapam.h"
  19 #include "catalog/catname.h"
  20 #include "catalog/dependency.h"
  21 #include "catalog/indexing.h"
  22 #include "catalog/pg_rewrite.h"
  23 #include "miscadmin.h"
  24 #include "rewrite/rewriteRemove.h"
  25 #include "rewrite/rewriteSupport.h"
  26 #include "utils/acl.h"
  27 #include "utils/fmgroids.h"
  28 #include "utils/lsyscache.h"
  29 #include "utils/syscache.h"
  30
  31
  32 /*
  33  * RemoveRewriteRule
  34  *
  35  * Delete a rule given its name.
  36  */
  37 void
  38 RemoveRewriteRule(Oid owningRel, const char *ruleName, DropBehavior behavior)
  39 {
  40         HeapTuple       tuple;
  41         Oid                     eventRelationOid;
  42         AclResult       aclresult;
  43         ObjectAddress object;
  44
  45         /*
  46          * Find the tuple for the target rule.
  47          */
  48         tuple = SearchSysCache(RULERELNAME,
  49                                                    ObjectIdGetDatum(owningRel),
  50                                                    PointerGetDatum(ruleName),
  51                                                    0, 0);
  52
  53         /*
  54          * complain if no rule with such name exists
  55          */
  56         if (!HeapTupleIsValid(tuple))
  57                 elog(ERROR, "Rule \"%s\" not found", ruleName);
  58
  59         /*
  60          * Verify user has appropriate permissions.
  61          */
  62         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
  63         Assert(eventRelationOid == owningRel);
  64         aclresult = pg_class_aclcheck(eventRelationOid, GetUserId(), ACL_RULE);
  65         if (aclresult != ACLCHECK_OK)
  66                 aclcheck_error(aclresult, get_rel_name(eventRelationOid));
  67
  68         /*
  69          * Do the deletion
  70          */
  71         object.classId = get_system_catalog_relid(RewriteRelationName);
  72         object.objectId = HeapTupleGetOid(tuple);
  73         object.objectSubId = 0;
  74
  75         ReleaseSysCache(tuple);
  76
  77         performDeletion(&object, behavior);
  78 }
  79
  80
  81 /*
  82  * Guts of rule deletion.
  83  */
  84 void
  85 RemoveRewriteRuleById(Oid ruleOid)
  86 {
  87         Relation        RewriteRelation;
  88         ScanKeyData             skey[1];
  89         SysScanDesc             rcscan;
  90         Relation        event_relation;
  91         HeapTuple       tuple;
  92         Oid                     eventRelationOid;
  93         bool            hasMoreRules;
  94
  95         /*
  96          * Open the pg_rewrite relation.
  97          */
  98         RewriteRelation = heap_openr(RewriteRelationName, RowExclusiveLock);
  99
 100         /*
 101          * Find the tuple for the target rule.
 102          */
 103         ScanKeyEntryInitialize(&skey[0], 0x0,
 104                                                    ObjectIdAttributeNumber, F_OIDEQ,
 105                                                    ObjectIdGetDatum(ruleOid));
 106
 107         rcscan = systable_beginscan(RewriteRelation, RewriteOidIndex, true,
 108                                                                 SnapshotNow, 1, skey);
 109
 110         tuple = systable_getnext(rcscan);
 111
 112         if (!HeapTupleIsValid(tuple))
 113                 elog(ERROR, "RemoveRewriteRuleById: Rule %u does not exist",
 114                          ruleOid);
 115
 116         /*
 117          * We had better grab AccessExclusiveLock so that we know no other
 118          * rule additions/deletions are going on for this relation.  Else we
 119          * cannot set relhasrules correctly.  Besides, we don't want to be
 120          * changing the ruleset while queries are executing on the rel.
 121          */
 122         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
 123         event_relation = heap_open(eventRelationOid, AccessExclusiveLock);
 124
 125         hasMoreRules = event_relation->rd_rules != NULL &&
 126                 event_relation->rd_rules->numLocks > 1;
 127
 128         /*
 129          * Now delete the pg_rewrite tuple for the rule
 130          */
 131         simple_heap_delete(RewriteRelation, &tuple->t_self);
 132
 133         systable_endscan(rcscan);
 134
 135         heap_close(RewriteRelation, RowExclusiveLock);
 136
 137         /*
 138          * Set pg_class 'relhasrules' field correctly for event relation.
 139          *
 140          * Important side effect: an SI notice is broadcast to force all backends
 141          * (including me!) to update relcache entries with the new rule set.
 142          * Therefore, must do this even if relhasrules is still true!
 143          */
 144         SetRelationRuleStatus(eventRelationOid, hasMoreRules, false);
 145
 146         /* Close rel, but keep lock till commit... */
 147         heap_close(event_relation, NoLock);
 148 }