src/backend/rewrite/rewriteSupport.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * rewriteSupport.c
   4  *
   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/heapam.h"
  18 #include "catalog/indexing.h"
  19 #include "catalog/pg_class.h"
  20 #include "rewrite/rewriteSupport.h"
  21 #include "utils/inval.h"
  22 #include "utils/syscache.h"
  23
  24
  25 /*
  26  * Is there a rule by the given name?
  27  */
  28 bool
  29 IsDefinedRewriteRule(Oid owningRel, const char *ruleName)
  30 {
  31         return SearchSysCacheExists(RULERELNAME,
  32                                                                 ObjectIdGetDatum(owningRel),
  33                                                                 PointerGetDatum(ruleName),
  34                                                                 0, 0);
  35 }
  36
  37
  38 /*
  39  * SetRelationRuleStatus
  40  *              Set the value of the relation's relhasrules field in pg_class;
  41  *              if the relation is becoming a view, also adjust its relkind.
  42  *
  43  * NOTE: caller must be holding an appropriate lock on the relation.
  44  *
  45  * NOTE: an important side-effect of this operation is that an SI invalidation
  46  * message is sent out to all backends --- including me --- causing relcache
  47  * entries to be flushed or updated with the new set of rules for the table.
  48  * This must happen even if we find that no change is needed in the pg_class
  49  * row.
  50  */
  51 void
  52 SetRelationRuleStatus(Oid relationId, bool relHasRules,
  53                                           bool relIsBecomingView)
  54 {
  55         Relation        relationRelation;
  56         HeapTuple       tuple;
  57         Form_pg_class classForm;
  58
  59         /*
  60          * Find the tuple to update in pg_class, using syscache for the lookup.
  61          */
  62         relationRelation = heap_open(RelationRelationId, RowExclusiveLock);
  63         tuple = SearchSysCacheCopy(RELOID,
  64                                                            ObjectIdGetDatum(relationId),
  65                                                            0, 0, 0);
  66         if (!HeapTupleIsValid(tuple))
  67                 elog(ERROR, "cache lookup failed for relation %u", relationId);
  68         classForm = (Form_pg_class) GETSTRUCT(tuple);
  69
  70         if (classForm->relhasrules != relHasRules ||
  71                 (relIsBecomingView && classForm->relkind != RELKIND_VIEW))
  72         {
  73                 /* Do the update */
  74                 classForm->relhasrules = relHasRules;
  75                 if (relIsBecomingView)
  76                         classForm->relkind = RELKIND_VIEW;
  77
  78                 simple_heap_update(relationRelation, &tuple->t_self, tuple);
  79
  80                 /* Keep the catalog indexes up to date */
  81                 CatalogUpdateIndexes(relationRelation, tuple);
  82         }
  83         else
  84         {
  85                 /* no need to change tuple, but force relcache rebuild anyway */
  86                 CacheInvalidateRelcacheByTuple(tuple);
  87         }
  88
  89         heap_freetuple(tuple);
  90         heap_close(relationRelation, RowExclusiveLock);
  91 }