granicus.if.org Git - postgresql/blob - src/backend/rewrite/rewriteRemove.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteRemove.c
   4  *        routines for removing rewrite rules
   5  *
   6  * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        src/backend/rewrite/rewriteRemove.c
  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/namespace.h"
  23 #include "catalog/pg_rewrite.h"
  24 #include "miscadmin.h"
  25 #include "rewrite/rewriteRemove.h"
  26 #include "utils/acl.h"
  27 #include "utils/fmgroids.h"
  28 #include "utils/inval.h"
  29 #include "utils/lsyscache.h"
  30 #include "utils/syscache.h"
  31 #include "utils/tqual.h"
  32
  33 /*
  34  * Guts of rule deletion.
  35  */
  36 void
  37 RemoveRewriteRuleById(Oid ruleOid)
  38 {
  39         Relation        RewriteRelation;
  40         ScanKeyData skey[1];
  41         SysScanDesc rcscan;
  42         Relation        event_relation;
  43         HeapTuple       tuple;
  44         Oid                     eventRelationOid;
  45
  46         /*
  47          * Open the pg_rewrite relation.
  48          */
  49         RewriteRelation = heap_open(RewriteRelationId, RowExclusiveLock);
  50
  51         /*
  52          * Find the tuple for the target rule.
  53          */
  54         ScanKeyInit(&skey[0],
  55                                 ObjectIdAttributeNumber,
  56                                 BTEqualStrategyNumber, F_OIDEQ,
  57                                 ObjectIdGetDatum(ruleOid));
  58
  59         rcscan = systable_beginscan(RewriteRelation, RewriteOidIndexId, true,
  60                                                                 SnapshotNow, 1, skey);
  61
  62         tuple = systable_getnext(rcscan);
  63
  64         if (!HeapTupleIsValid(tuple))
  65                 elog(ERROR, "could not find tuple for rule %u", ruleOid);
  66
  67         /*
  68          * We had better grab AccessExclusiveLock to ensure that no queries are
  69          * going on that might depend on this rule.  (Note: a weaker lock would
  70          * suffice if it's not an ON SELECT rule.)
  71          */
  72         eventRelationOid = ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class;
  73         event_relation = heap_open(eventRelationOid, AccessExclusiveLock);
  74
  75         /*
  76          * Now delete the pg_rewrite tuple for the rule
  77          */
  78         simple_heap_delete(RewriteRelation, &tuple->t_self);
  79
  80         systable_endscan(rcscan);
  81
  82         heap_close(RewriteRelation, RowExclusiveLock);
  83
  84         /*
  85          * Issue shared-inval notice to force all backends (including me!) to
  86          * update relcache entries with the new rule set.
  87          */
  88         CacheInvalidateRelcache(event_relation);
  89
  90         /* Close rel, but keep lock till commit... */
  91         heap_close(event_relation, NoLock);
  92 }