1996-07-09 08:22:35 +02:00
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/*-------------------------------------------------------------------------
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*
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1999-02-14 00:22:53 +01:00
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* rewriteSupport.c
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1997-09-07 07:04:48 +02:00
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*
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1996-07-09 08:22:35 +02:00
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*
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2014-01-07 22:05:30 +01:00
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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2000-01-26 06:58:53 +01:00
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* Portions Copyright (c) 1994, Regents of the University of California
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1996-07-09 08:22:35 +02:00
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*
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*
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* IDENTIFICATION
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2010-09-20 22:08:53 +02:00
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* src/backend/rewrite/rewriteSupport.c
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1996-07-09 08:22:35 +02:00
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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1998-04-27 06:08:07 +02:00
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#include "access/heapam.h"
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2012-08-30 22:15:44 +02:00
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#include "access/htup_details.h"
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1998-04-27 06:08:07 +02:00
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#include "catalog/indexing.h"
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2010-08-05 17:25:36 +02:00
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#include "catalog/pg_rewrite.h"
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1999-07-16 07:00:38 +02:00
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#include "rewrite/rewriteSupport.h"
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2010-08-05 17:25:36 +02:00
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#include "utils/fmgroids.h"
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2002-07-12 20:43:19 +02:00
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#include "utils/inval.h"
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2010-08-05 17:25:36 +02:00
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#include "utils/lsyscache.h"
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#include "utils/rel.h"
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1999-07-16 05:14:30 +02:00
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#include "utils/syscache.h"
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2010-08-05 17:25:36 +02:00
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#include "utils/tqual.h"
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1998-04-27 06:08:07 +02:00
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2001-08-12 23:35:19 +02:00
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/*
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* Is there a rule by the given name?
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*/
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2000-11-16 23:30:52 +01:00
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bool
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2002-04-18 22:01:11 +02:00
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IsDefinedRewriteRule(Oid owningRel, const char *ruleName)
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1996-07-09 08:22:35 +02:00
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{
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2010-02-14 19:42:19 +01:00
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return SearchSysCacheExists2(RULERELNAME,
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ObjectIdGetDatum(owningRel),
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PointerGetDatum(ruleName));
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1996-07-09 08:22:35 +02:00
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}
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2001-08-12 23:35:19 +02:00
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2000-06-30 09:04:23 +02:00
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/*
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2000-09-29 20:21:41 +02:00
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* SetRelationRuleStatus
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2013-03-04 01:05:47 +01:00
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* Set the value of the relation's relhasrules field in pg_class.
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2000-06-30 09:04:23 +02:00
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*
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2000-09-29 20:21:41 +02:00
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* NOTE: caller must be holding an appropriate lock on the relation.
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2000-06-30 09:04:23 +02:00
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*
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* NOTE: an important side-effect of this operation is that an SI invalidation
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* message is sent out to all backends --- including me --- causing relcache
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* entries to be flushed or updated with the new set of rules for the table.
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2002-07-12 20:43:19 +02:00
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* This must happen even if we find that no change is needed in the pg_class
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* row.
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2000-06-30 09:04:23 +02:00
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*/
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void
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2013-03-04 01:05:47 +01:00
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SetRelationRuleStatus(Oid relationId, bool relHasRules)
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1996-07-09 08:22:35 +02:00
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{
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1997-09-08 04:41:22 +02:00
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Relation relationRelation;
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HeapTuple tuple;
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2002-07-12 20:43:19 +02:00
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Form_pg_class classForm;
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1997-09-07 07:04:48 +02:00
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/*
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2005-10-15 04:49:52 +02:00
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* Find the tuple to update in pg_class, using syscache for the lookup.
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1997-09-07 07:04:48 +02:00
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*/
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2005-04-14 22:03:27 +02:00
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relationRelation = heap_open(RelationRelationId, RowExclusiveLock);
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2010-02-14 19:42:19 +01:00
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tuple = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relationId));
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2000-11-16 23:30:52 +01:00
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if (!HeapTupleIsValid(tuple))
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2003-07-25 02:01:09 +02:00
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elog(ERROR, "cache lookup failed for relation %u", relationId);
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2002-07-12 20:43:19 +02:00
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classForm = (Form_pg_class) GETSTRUCT(tuple);
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1997-09-07 07:04:48 +02:00
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2013-03-04 01:05:47 +01:00
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if (classForm->relhasrules != relHasRules)
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2002-07-12 20:43:19 +02:00
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{
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/* Do the update */
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classForm->relhasrules = relHasRules;
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2000-09-29 20:21:41 +02:00
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2002-07-12 20:43:19 +02:00
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simple_heap_update(relationRelation, &tuple->t_self, tuple);
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1997-09-07 07:04:48 +02:00
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2002-08-05 05:29:17 +02:00
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/* Keep the catalog indexes up to date */
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CatalogUpdateIndexes(relationRelation, tuple);
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2002-07-12 20:43:19 +02:00
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}
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else
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{
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/* no need to change tuple, but force relcache rebuild anyway */
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2004-02-10 02:55:27 +01:00
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CacheInvalidateRelcacheByTuple(tuple);
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2002-07-12 20:43:19 +02:00
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}
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1997-09-07 07:04:48 +02:00
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1999-12-16 23:20:03 +01:00
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heap_freetuple(tuple);
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1999-09-18 21:08:25 +02:00
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heap_close(relationRelation, RowExclusiveLock);
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1996-07-09 08:22:35 +02:00
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}
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2010-08-05 17:25:36 +02:00
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/*
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* Find rule oid.
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*
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* If missing_ok is false, throw an error if rule name not found. If
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* true, just return InvalidOid.
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*/
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Oid
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get_rewrite_oid(Oid relid, const char *rulename, bool missing_ok)
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{
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HeapTuple tuple;
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Oid ruleoid;
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/* Find the rule's pg_rewrite tuple, get its OID */
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tuple = SearchSysCache2(RULERELNAME,
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ObjectIdGetDatum(relid),
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PointerGetDatum(rulename));
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if (!HeapTupleIsValid(tuple))
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{
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if (missing_ok)
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return InvalidOid;
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ereport(ERROR,
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(errcode(ERRCODE_UNDEFINED_OBJECT),
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errmsg("rule \"%s\" for relation \"%s\" does not exist",
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rulename, get_rel_name(relid))));
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}
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Assert(relid == ((Form_pg_rewrite) GETSTRUCT(tuple))->ev_class);
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ruleoid = HeapTupleGetOid(tuple);
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ReleaseSysCache(tuple);
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return ruleoid;
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}
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/*
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* Find rule oid, given only a rule name but no rel OID.
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*
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* If there's more than one, it's an error. If there aren't any, that's an
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2014-05-06 18:12:18 +02:00
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* error, too. In general, this should be avoided - it is provided to support
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2010-08-05 17:25:36 +02:00
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* syntax that is compatible with pre-7.3 versions of PG, where rule names
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* were unique across the entire database.
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*/
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Oid
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2011-06-28 03:17:25 +02:00
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get_rewrite_oid_without_relid(const char *rulename,
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Oid *reloid, bool missing_ok)
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2010-08-05 17:25:36 +02:00
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{
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Relation RewriteRelation;
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HeapScanDesc scanDesc;
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ScanKeyData scanKeyData;
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HeapTuple htup;
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Oid ruleoid;
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/* Search pg_rewrite for such a rule */
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ScanKeyInit(&scanKeyData,
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Anum_pg_rewrite_rulename,
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BTEqualStrategyNumber, F_NAMEEQ,
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CStringGetDatum(rulename));
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RewriteRelation = heap_open(RewriteRelationId, AccessShareLock);
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Use an MVCC snapshot, rather than SnapshotNow, for catalog scans.
SnapshotNow scans have the undesirable property that, in the face of
concurrent updates, the scan can fail to see either the old or the new
versions of the row. In many cases, we work around this by requiring
DDL operations to hold AccessExclusiveLock on the object being
modified; in some cases, the existing locking is inadequate and random
failures occur as a result. This commit doesn't change anything
related to locking, but will hopefully pave the way to allowing lock
strength reductions in the future.
The major issue has held us back from making this change in the past
is that taking an MVCC snapshot is significantly more expensive than
using a static special snapshot such as SnapshotNow. However, testing
of various worst-case scenarios reveals that this problem is not
severe except under fairly extreme workloads. To mitigate those
problems, we avoid retaking the MVCC snapshot for each new scan;
instead, we take a new snapshot only when invalidation messages have
been processed. The catcache machinery already requires that
invalidation messages be sent before releasing the related heavyweight
lock; else other backends might rely on locally-cached data rather
than scanning the catalog at all. Thus, making snapshot reuse
dependent on the same guarantees shouldn't break anything that wasn't
already subtly broken.
Patch by me. Review by Michael Paquier and Andres Freund.
2013-07-02 15:47:01 +02:00
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scanDesc = heap_beginscan_catalog(RewriteRelation, 1, &scanKeyData);
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2010-08-05 17:25:36 +02:00
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htup = heap_getnext(scanDesc, ForwardScanDirection);
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if (!HeapTupleIsValid(htup))
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2011-06-28 03:17:25 +02:00
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{
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if (!missing_ok)
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ereport(ERROR,
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(errcode(ERRCODE_UNDEFINED_OBJECT),
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errmsg("rule \"%s\" does not exist", rulename)));
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ruleoid = InvalidOid;
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}
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else
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{
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ruleoid = HeapTupleGetOid(htup);
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if (reloid != NULL)
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*reloid = ((Form_pg_rewrite) GETSTRUCT(htup))->ev_class;
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htup = heap_getnext(scanDesc, ForwardScanDirection);
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if (HeapTupleIsValid(htup))
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ereport(ERROR,
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(errcode(ERRCODE_DUPLICATE_OBJECT),
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2012-06-10 21:20:04 +02:00
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errmsg("there are multiple rules named \"%s\"", rulename),
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errhint("Specify a relation name as well as a rule name.")));
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2011-06-28 03:17:25 +02:00
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}
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2010-08-05 17:25:36 +02:00
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heap_endscan(scanDesc);
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heap_close(RewriteRelation, AccessShareLock);
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return ruleoid;
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}
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