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Commit4b21acf

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Introduce access/{table.h, relation.h}, for generic functions from heapam.h.
access/heapam contains functions that are very storage specific (sayheap_insert() and a lot of lower level functions), and fairly genericinfrastructure like relation_open(), heap_open() etc. In the upcomingpluggable storage work we're introducing a layer between tableaccesses in general and heapam, to allow for different storagemethods. For a bit cleaner separation it thus seems advantageous tomove generic functions like the aforementioned to their own headers.access/relation.h will contain relation_open() etc, and access/table.hwill contain table_open() (formerly known as heap_open()). I've decidedfor table.h not to include relation.h, but we might change that at alater stage.relation.h already exists in another directory, but the otherplausible name (rel.h) also conflicts. It'd be nice if there were anon-conflicting name, but nobody came up with a suggestion. It'spossible that the appropriate way to address the naming conflict wouldbe to rename nodes/relation.h, which isn't particularly well named.To avoid breaking a lot of extensions that just use heap_open() etc,table.h has macros mapping the old names to the new ones, and heapam.hincludes relation, table.h. That also allows to keep thebulk renaming of existing callers in a separate commit.Author: Andres FreundDiscussion:https://postgr.es/m/20190111000539.xbv7s6w7ilcvm7dp@alap3.anarazel.de
1 parentf1ad067 commit4b21acf

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9 files changed

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‎src/backend/access/Makefile‎

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@@ -9,6 +9,6 @@ top_builddir = ../../..
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include$(top_builddir)/src/Makefile.global
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SUBDIRS = brin common gin gist hash heap index nbtree rmgrdesc spgist\
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tablesample transam
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tabletablesample transam
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include$(top_srcdir)/src/backend/common.mk

‎src/backend/access/common/Makefile‎

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include$(top_builddir)/src/Makefile.global
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OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o\
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reloptions.o scankey.o session.o tupconvert.o tupdesc.o
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relation.oreloptions.o scankey.o session.o tupconvert.o tupdesc.o
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include$(top_srcdir)/src/backend/common.mk
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/*-------------------------------------------------------------------------
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*
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* relation.c
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* Generic relation related routines.
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*
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* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* src/backend/access/common/relation.c
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*
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* NOTES
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* This file contains relation_ routines that implement access to relations
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* (tables, indexes, etc). Support that's specific to subtypes of relations
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* should go into their respective files, not here.
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*
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*-------------------------------------------------------------------------
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*/
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#include"postgres.h"
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#include"access/relation.h"
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#include"access/xact.h"
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#include"catalog/namespace.h"
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#include"miscadmin.h"
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#include"pgstat.h"
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#include"storage/lmgr.h"
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#include"utils/inval.h"
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#include"utils/syscache.h"
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/* ----------------
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*relation_open - open any relation by relation OID
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*
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*If lockmode is not "NoLock", the specified kind of lock is
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*obtained on the relation. (Generally, NoLock should only be
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*used if the caller knows it has some appropriate lock on the
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*relation already.)
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*
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*An error is raised if the relation does not exist.
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*
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*NB: a "relation" is anything with a pg_class entry. The caller is
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*expected to check whether the relkind is something it can handle.
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* ----------------
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*/
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Relation
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relation_open(OidrelationId,LOCKMODElockmode)
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{
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Relationr;
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Assert(lockmode >=NoLock&&lockmode<MAX_LOCKMODES);
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/* Get the lock before trying to open the relcache entry */
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if (lockmode!=NoLock)
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LockRelationOid(relationId,lockmode);
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/* The relcache does all the real work... */
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r=RelationIdGetRelation(relationId);
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if (!RelationIsValid(r))
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elog(ERROR,"could not open relation with OID %u",relationId);
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/*
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* If we didn't get the lock ourselves, assert that caller holds one,
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* except in bootstrap mode where no locks are used.
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*/
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Assert(lockmode!=NoLock||
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IsBootstrapProcessingMode()||
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CheckRelationLockedByMe(r,AccessShareLock, true));
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/* Make note that we've accessed a temporary relation */
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if (RelationUsesLocalBuffers(r))
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MyXactFlags |=XACT_FLAGS_ACCESSEDTEMPREL;
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pgstat_initstats(r);
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returnr;
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}
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/* ----------------
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*try_relation_open - open any relation by relation OID
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*
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*Same as relation_open, except return NULL instead of failing
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*if the relation does not exist.
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* ----------------
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*/
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Relation
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try_relation_open(OidrelationId,LOCKMODElockmode)
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{
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Relationr;
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Assert(lockmode >=NoLock&&lockmode<MAX_LOCKMODES);
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/* Get the lock first */
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if (lockmode!=NoLock)
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LockRelationOid(relationId,lockmode);
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/*
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* Now that we have the lock, probe to see if the relation really exists
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* or not.
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*/
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if (!SearchSysCacheExists1(RELOID,ObjectIdGetDatum(relationId)))
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{
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/* Release useless lock */
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if (lockmode!=NoLock)
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UnlockRelationOid(relationId,lockmode);
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returnNULL;
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}
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/* Should be safe to do a relcache load */
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r=RelationIdGetRelation(relationId);
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if (!RelationIsValid(r))
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elog(ERROR,"could not open relation with OID %u",relationId);
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/* If we didn't get the lock ourselves, assert that caller holds one */
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Assert(lockmode!=NoLock||
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CheckRelationLockedByMe(r,AccessShareLock, true));
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/* Make note that we've accessed a temporary relation */
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if (RelationUsesLocalBuffers(r))
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MyXactFlags |=XACT_FLAGS_ACCESSEDTEMPREL;
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pgstat_initstats(r);
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returnr;
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}
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/* ----------------
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*relation_openrv - open any relation specified by a RangeVar
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*
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*Same as relation_open, but the relation is specified by a RangeVar.
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* ----------------
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*/
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Relation
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relation_openrv(constRangeVar*relation,LOCKMODElockmode)
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{
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OidrelOid;
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/*
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* Check for shared-cache-inval messages before trying to open the
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* relation. This is needed even if we already hold a lock on the
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* relation, because GRANT/REVOKE are executed without taking any lock on
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* the target relation, and we want to be sure we see current ACL
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* information. We can skip this if asked for NoLock, on the assumption
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* that such a call is not the first one in the current command, and so we
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* should be reasonably up-to-date already. (XXX this all could stand to
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* be redesigned, but for the moment we'll keep doing this like it's been
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* done historically.)
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*/
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if (lockmode!=NoLock)
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AcceptInvalidationMessages();
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/* Look up and lock the appropriate relation using namespace search */
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relOid=RangeVarGetRelid(relation,lockmode, false);
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/* Let relation_open do the rest */
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returnrelation_open(relOid,NoLock);
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}
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/* ----------------
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*relation_openrv_extended - open any relation specified by a RangeVar
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*
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*Same as relation_openrv, but with an additional missing_ok argument
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*allowing a NULL return rather than an error if the relation is not
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*found. (Note that some other causes, such as permissions problems,
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*will still result in an ereport.)
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* ----------------
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*/
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Relation
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relation_openrv_extended(constRangeVar*relation,LOCKMODElockmode,
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boolmissing_ok)
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{
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OidrelOid;
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/*
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* Check for shared-cache-inval messages before trying to open the
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* relation. See comments in relation_openrv().
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*/
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if (lockmode!=NoLock)
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AcceptInvalidationMessages();
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/* Look up and lock the appropriate relation using namespace search */
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relOid=RangeVarGetRelid(relation,lockmode,missing_ok);
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/* Return NULL on not-found */
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if (!OidIsValid(relOid))
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returnNULL;
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/* Let relation_open do the rest */
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returnrelation_open(relOid,NoLock);
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}
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/* ----------------
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*relation_close - close any relation
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*
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*If lockmode is not "NoLock", we then release the specified lock.
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*
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*Note that it is often sensible to hold a lock beyond relation_close;
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*in that case, the lock is released automatically at xact end.
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* ----------------
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*/
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void
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relation_close(Relationrelation,LOCKMODElockmode)
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{
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LockRelIdrelid=relation->rd_lockInfo.lockRelId;
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Assert(lockmode >=NoLock&&lockmode<MAX_LOCKMODES);
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/* The relcache does the real work... */
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RelationClose(relation);
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if (lockmode!=NoLock)
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UnlockRelationId(&relid,lockmode);
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}

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