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/*-------------------------------------------------------------------------
*
* rewriteSupport.c
*
*
* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/rewrite/rewriteSupport.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "catalog/indexing.h"
#include "catalog/pg_rewrite.h"
#include "rewrite/rewriteSupport.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/tqual.h"
/*
* Is there a rule by the given name?
*/
bool
IsDefinedRewriteRule(Oid owningRel, const char *ruleName)
{
return SearchSysCacheExists2(RULERELNAME,
ObjectIdGetDatum(owningRel),
PointerGetDatum(ruleName));
}
/*
* SetRelationRuleStatus
* Set the value of the relation's relhasrules field in pg_class;
* if the relation is becoming a view, also adjust its relkind.
*
* NOTE: caller must be holding an appropriate lock on the relation.
*
* NOTE: an important side-effect of this operation is that an SI invalidation
* message is sent out to all backends --- including me --- causing relcache
* entries to be flushed or updated with the new set of rules for the table.
* This must happen even if we find that no change is needed in the pg_class
* row.
*/
void
SetRelationRuleStatus(Oid relationId, bool relHasRules,
bool relIsBecomingView)
{
Relation relationRelation;
HeapTuple tuple;
Form_pg_class classForm;
/*
* Find the tuple to update in pg_class, using syscache for the lookup.
*/
relationRelation = heap_open(RelationRelationId, RowExclusiveLock);
tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relationId));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for relation %u", relationId);
classForm = (Form_pg_class) GETSTRUCT(tuple);
if (classForm->relhasrules != relHasRules ||
(relIsBecomingView && classForm->relkind != RELKIND_VIEW))
{
/* Do the update */
classForm->relhasrules = relHasRules;
if (relIsBecomingView)
classForm->relkind = RELKIND_VIEW;
simple_heap_update(relationRelation, &tuple->t_self, tuple);
/* Keep the catalog indexes up to date */
CatalogUpdateIndexes(relationRelation, tuple);
}
else
{
/* no need to change tuple, but force relcache rebuild anyway */
CacheInvalidateRelcacheByTuple(tuple);
}
heap_freetuple(tuple);
heap_close(relationRelation, RowExclusiveLock);
}
/*
* Find rule oid.
*
* If missing_ok is false, throw an error if rule name not found. If
* true, just return InvalidOid.
*/
Oid
get_rewrite_oid(Oid relid, const char *rulename, bool missing_ok)
{
HeapTuple tuple;
Oid ruleoid;
/* Find the rule's pg_rewrite tuple, get its OID */
tuple = SearchSysCache2(RULERELNAME,
ObjectIdGetDatum(relid),
PointerGetDatum(rulename));
if (!HeapTupleIsValid(tuple))
{
if (missing_ok)
return InvalidOid;
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("rule \"%s\" for relation \"%s\" does not exist",
rulename, get_rel_name(relid))));
}
Assert(relid == ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class);
ruleoid = HeapTupleGetOid(tuple);
ReleaseSysCache(tuple);
return ruleoid;
}
/*
* Find rule oid, given only a rule name but no rel OID.
*
* If there's more than one, it's an error. If there aren't any, that's an
* error, too. In general, this should be avoided - it is provided to support
* syntax that is compatible with pre-7.3 versions of PG, where rule names
* were unique across the entire database.
*/
Oid
get_rewrite_oid_without_relid(const char *rulename,
Oid *reloid, bool missing_ok)
{
Relation RewriteRelation;
HeapScanDesc scanDesc;
ScanKeyData scanKeyData;
HeapTuple htup;
Oid ruleoid;
/* Search pg_rewrite for such a rule */
ScanKeyInit(&scanKeyData,
Anum_pg_rewrite_rulename,
BTEqualStrategyNumber, F_NAMEEQ,
CStringGetDatum(rulename));
RewriteRelation = heap_open(RewriteRelationId, AccessShareLock);
scanDesc = heap_beginscan(RewriteRelation, SnapshotNow, 1, &scanKeyData);
htup = heap_getnext(scanDesc, ForwardScanDirection);
if (!HeapTupleIsValid(htup))
{
if (!missing_ok)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("rule \"%s\" does not exist", rulename)));
ruleoid = InvalidOid;
}
else
{
ruleoid = HeapTupleGetOid(htup);
if (reloid != NULL)
*reloid = ((Form_pg_rewrite) GETSTRUCT(htup))->ev_class;
htup = heap_getnext(scanDesc, ForwardScanDirection);
if (HeapTupleIsValid(htup))
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("there are multiple rules named \"%s\"", rulename),
errhint("Specify a relation name as well as a rule name.")));
}
heap_endscan(scanDesc);
heap_close(RewriteRelation, AccessShareLock);
return ruleoid;
}
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