src/backend/rewrite/rewriteRemove.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteRemove.c
   4  *        routines for removing rewrite rules
   5  *
   6  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/genam.h"
  18 #include "access/heapam.h"
  19 #include "access/sysattr.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 "utils/acl.h"
  26 #include "utils/fmgroids.h"
  27 #include "utils/inval.h"
  28 #include "utils/lsyscache.h"
  29 #include "utils/rel.h"
  30 #include "utils/syscache.h"
  31 #include "utils/tqual.h"
  32
  33
  34 /*
  35  * RemoveRewriteRule
  36  *
  37  * Delete a rule given its name.
  38  */
  39 void
  40 RemoveRewriteRule(Oid owningRel, const char *ruleName, DropBehavior behavior,
  41                                   bool missing_ok)
  42 {
  43         HeapTuple       tuple;
  44         Oid                     eventRelationOid;
  45         ObjectAddress object;
  46
  47         /*
  48          * Find the tuple for the target rule.
  49          */
  50         tuple = SearchSysCache(RULERELNAME,
  51                                                    ObjectIdGetDatum(owningRel),
  52                                                    PointerGetDatum(ruleName),
  53                                                    0, 0);
  54
  55         /*
  56          * complain if no rule with such name exists
  57          */
  58         if (!HeapTupleIsValid(tuple))
  59         {
  60                 if (!missing_ok)
  61                         ereport(ERROR,
  62                                         (errcode(ERRCODE_UNDEFINED_OBJECT),
  63                                          errmsg("rule \"%s\" for relation \"%s\" does not exist",
  64                                                         ruleName, get_rel_name(owningRel))));
  65                 else
  66                         ereport(NOTICE,
  67                                         (errmsg("rule \"%s\" for relation \"%s\" does not exist, skipping",
  68                                                         ruleName, get_rel_name(owningRel))));
  69                 return;
  70         }
  71
  72         /*
  73          * Verify user has appropriate permissions.
  74          */
  75         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
  76         Assert(eventRelationOid == owningRel);
  77         if (!pg_class_ownercheck(eventRelationOid, GetUserId()))
  78                 aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
  79                                            get_rel_name(eventRelationOid));
  80
  81         /*
  82          * Do the deletion
  83          */
  84         object.classId = RewriteRelationId;
  85         object.objectId = HeapTupleGetOid(tuple);
  86         object.objectSubId = 0;
  87
  88         ReleaseSysCache(tuple);
  89
  90         performDeletion(&object, behavior);
  91 }
  92
  93
  94 /*
  95  * Guts of rule deletion.
  96  */
  97 void
  98 RemoveRewriteRuleById(Oid ruleOid)
  99 {
 100         Relation        RewriteRelation;
 101         ScanKeyData skey[1];
 102         SysScanDesc rcscan;
 103         Relation        event_relation;
 104         HeapTuple       tuple;
 105         Oid                     eventRelationOid;
 106
 107         /*
 108          * Open the pg_rewrite relation.
 109          */
 110         RewriteRelation = heap_open(RewriteRelationId, RowExclusiveLock);
 111
 112         /*
 113          * Find the tuple for the target rule.
 114          */
 115         ScanKeyInit(&skey[0],
 116                                 ObjectIdAttributeNumber,
 117                                 BTEqualStrategyNumber, F_OIDEQ,
 118                                 ObjectIdGetDatum(ruleOid));
 119
 120         rcscan = systable_beginscan(RewriteRelation, RewriteOidIndexId, true,
 121                                                                 SnapshotNow, 1, skey);
 122
 123         tuple = systable_getnext(rcscan);
 124
 125         if (!HeapTupleIsValid(tuple))
 126                 elog(ERROR, "could not find tuple for rule %u", ruleOid);
 127
 128         /*
 129          * We had better grab AccessExclusiveLock to ensure that no queries
 130          * are going on that might depend on this rule.  (Note: a weaker lock
 131          * would suffice if it's not an ON SELECT rule.)
 132          */
 133         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
 134         event_relation = heap_open(eventRelationOid, AccessExclusiveLock);
 135
 136         /*
 137          * Now delete the pg_rewrite tuple for the rule
 138          */
 139         simple_heap_delete(RewriteRelation, &tuple->t_self);
 140
 141         systable_endscan(rcscan);
 142
 143         heap_close(RewriteRelation, RowExclusiveLock);
 144
 145         /*
 146          * Issue shared-inval notice to force all backends (including me!) to
 147          * update relcache entries with the new rule set.
 148          */
 149         CacheInvalidateRelcache(event_relation);
 150
 151         /* Close rel, but keep lock till commit... */
 152         heap_close(event_relation, NoLock);
 153 }