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665d1fad99
- Add PUBLICATION catalogs and DDL - Add SUBSCRIPTION catalog and DDL - Define logical replication protocol and output plugin - Add logical replication workers From: Petr Jelinek <petr@2ndquadrant.com> Reviewed-by: Steve Singer <steve@ssinger.info> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Erik Rijkers <er@xs4all.nl> Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
460 lines
14 KiB
C
460 lines
14 KiB
C
/*-------------------------------------------------------------------------
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*
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* catalog.c
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* routines concerned with catalog naming conventions and other
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* bits of hard-wired knowledge
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*
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*
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* Portions Copyright (c) 1996-2017, 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/catalog/catalog.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <fcntl.h>
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#include <unistd.h>
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#include "access/genam.h"
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#include "access/sysattr.h"
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#include "access/transam.h"
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#include "catalog/catalog.h"
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#include "catalog/indexing.h"
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#include "catalog/namespace.h"
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#include "catalog/pg_auth_members.h"
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#include "catalog/pg_authid.h"
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#include "catalog/pg_database.h"
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#include "catalog/pg_namespace.h"
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#include "catalog/pg_pltemplate.h"
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#include "catalog/pg_db_role_setting.h"
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#include "catalog/pg_replication_origin.h"
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#include "catalog/pg_shdepend.h"
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#include "catalog/pg_shdescription.h"
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#include "catalog/pg_shseclabel.h"
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#include "catalog/pg_subscription.h"
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#include "catalog/pg_tablespace.h"
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#include "catalog/toasting.h"
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#include "miscadmin.h"
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#include "storage/fd.h"
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#include "utils/fmgroids.h"
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#include "utils/rel.h"
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#include "utils/tqual.h"
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/*
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* IsSystemRelation
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* True iff the relation is either a system catalog or toast table.
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* By a system catalog, we mean one that created in the pg_catalog schema
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* during initdb. User-created relations in pg_catalog don't count as
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* system catalogs.
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*
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* NB: TOAST relations are considered system relations by this test
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* for compatibility with the old IsSystemRelationName function.
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* This is appropriate in many places but not all. Where it's not,
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* also check IsToastRelation or use IsCatalogRelation().
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*/
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bool
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IsSystemRelation(Relation relation)
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{
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return IsSystemClass(RelationGetRelid(relation), relation->rd_rel);
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}
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/*
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* IsSystemClass
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* Like the above, but takes a Form_pg_class as argument.
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* Used when we do not want to open the relation and have to
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* search pg_class directly.
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*/
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bool
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IsSystemClass(Oid relid, Form_pg_class reltuple)
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{
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return IsToastClass(reltuple) || IsCatalogClass(relid, reltuple);
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}
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/*
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* IsCatalogRelation
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* True iff the relation is a system catalog, or the toast table for
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* a system catalog. By a system catalog, we mean one that created
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* in the pg_catalog schema during initdb. As with IsSystemRelation(),
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* user-created relations in pg_catalog don't count as system catalogs.
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*
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* Note that IsSystemRelation() returns true for ALL toast relations,
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* but this function returns true only for toast relations of system
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* catalogs.
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*/
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bool
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IsCatalogRelation(Relation relation)
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{
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return IsCatalogClass(RelationGetRelid(relation), relation->rd_rel);
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}
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/*
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* IsCatalogClass
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* True iff the relation is a system catalog relation.
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*
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* Check IsCatalogRelation() for details.
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*/
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bool
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IsCatalogClass(Oid relid, Form_pg_class reltuple)
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{
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Oid relnamespace = reltuple->relnamespace;
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/*
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* Never consider relations outside pg_catalog/pg_toast to be catalog
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* relations.
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*/
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if (!IsSystemNamespace(relnamespace) && !IsToastNamespace(relnamespace))
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return false;
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/* ----
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* Check whether the oid was assigned during initdb, when creating the
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* initial template database. Minus the relations in information_schema
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* excluded above, these are integral part of the system.
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* We could instead check whether the relation is pinned in pg_depend, but
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* this is noticeably cheaper and doesn't require catalog access.
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*
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* This test is safe since even an oid wraparound will preserve this
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* property (c.f. GetNewObjectId()) and it has the advantage that it works
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* correctly even if a user decides to create a relation in the pg_catalog
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* namespace.
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* ----
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*/
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return relid < FirstNormalObjectId;
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}
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/*
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* IsToastRelation
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* True iff relation is a TOAST support relation (or index).
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*/
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bool
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IsToastRelation(Relation relation)
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{
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return IsToastNamespace(RelationGetNamespace(relation));
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}
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/*
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* IsToastClass
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* Like the above, but takes a Form_pg_class as argument.
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* Used when we do not want to open the relation and have to
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* search pg_class directly.
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*/
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bool
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IsToastClass(Form_pg_class reltuple)
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{
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Oid relnamespace = reltuple->relnamespace;
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return IsToastNamespace(relnamespace);
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}
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/*
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* IsSystemNamespace
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* True iff namespace is pg_catalog.
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*
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* NOTE: the reason this isn't a macro is to avoid having to include
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* catalog/pg_namespace.h in a lot of places.
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*/
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bool
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IsSystemNamespace(Oid namespaceId)
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{
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return namespaceId == PG_CATALOG_NAMESPACE;
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}
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/*
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* IsToastNamespace
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* True iff namespace is pg_toast or my temporary-toast-table namespace.
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*
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* Note: this will return false for temporary-toast-table namespaces belonging
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* to other backends. Those are treated the same as other backends' regular
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* temp table namespaces, and access is prevented where appropriate.
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*/
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bool
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IsToastNamespace(Oid namespaceId)
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{
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return (namespaceId == PG_TOAST_NAMESPACE) ||
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isTempToastNamespace(namespaceId);
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}
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/*
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* IsReservedName
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* True iff name starts with the pg_ prefix.
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*
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* For some classes of objects, the prefix pg_ is reserved for
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* system objects only. As of 8.0, this was only true for
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* schema and tablespace names. With 9.6, this is also true
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* for roles.
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*/
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bool
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IsReservedName(const char *name)
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{
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/* ugly coding for speed */
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return (name[0] == 'p' &&
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name[1] == 'g' &&
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name[2] == '_');
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}
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/*
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* IsSharedRelation
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* Given the OID of a relation, determine whether it's supposed to be
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* shared across an entire database cluster.
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*
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* In older releases, this had to be hard-wired so that we could compute the
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* locktag for a relation and lock it before examining its catalog entry.
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* Since we now have MVCC catalog access, the race conditions that made that
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* a hard requirement are gone, so we could look at relaxing this restriction.
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* However, if we scanned the pg_class entry to find relisshared, and only
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* then locked the relation, pg_class could get updated in the meantime,
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* forcing us to scan the relation again, which would definitely be complex
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* and might have undesirable performance consequences. Fortunately, the set
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* of shared relations is fairly static, so a hand-maintained list of their
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* OIDs isn't completely impractical.
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*/
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bool
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IsSharedRelation(Oid relationId)
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{
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/* These are the shared catalogs (look for BKI_SHARED_RELATION) */
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if (relationId == AuthIdRelationId ||
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relationId == AuthMemRelationId ||
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relationId == DatabaseRelationId ||
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relationId == PLTemplateRelationId ||
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relationId == SharedDescriptionRelationId ||
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relationId == SharedDependRelationId ||
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relationId == SharedSecLabelRelationId ||
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relationId == TableSpaceRelationId ||
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relationId == DbRoleSettingRelationId ||
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relationId == ReplicationOriginRelationId ||
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relationId == SubscriptionRelationId)
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return true;
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/* These are their indexes (see indexing.h) */
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if (relationId == AuthIdRolnameIndexId ||
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relationId == AuthIdOidIndexId ||
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relationId == AuthMemRoleMemIndexId ||
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relationId == AuthMemMemRoleIndexId ||
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relationId == DatabaseNameIndexId ||
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relationId == DatabaseOidIndexId ||
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relationId == PLTemplateNameIndexId ||
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relationId == SharedDescriptionObjIndexId ||
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relationId == SharedDependDependerIndexId ||
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relationId == SharedDependReferenceIndexId ||
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relationId == SharedSecLabelObjectIndexId ||
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relationId == TablespaceOidIndexId ||
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relationId == TablespaceNameIndexId ||
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relationId == DbRoleSettingDatidRolidIndexId ||
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relationId == ReplicationOriginIdentIndex ||
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relationId == ReplicationOriginNameIndex ||
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relationId == SubscriptionObjectIndexId ||
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relationId == SubscriptionNameIndexId)
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return true;
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/* These are their toast tables and toast indexes (see toasting.h) */
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if (relationId == PgShdescriptionToastTable ||
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relationId == PgShdescriptionToastIndex ||
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relationId == PgDbRoleSettingToastTable ||
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relationId == PgDbRoleSettingToastIndex ||
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relationId == PgShseclabelToastTable ||
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relationId == PgShseclabelToastIndex)
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return true;
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return false;
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}
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/*
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* GetNewOid
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* Generate a new OID that is unique within the given relation.
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*
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* Caller must have a suitable lock on the relation.
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*
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* Uniqueness is promised only if the relation has a unique index on OID.
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* This is true for all system catalogs that have OIDs, but might not be
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* true for user tables. Note that we are effectively assuming that the
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* table has a relatively small number of entries (much less than 2^32)
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* and there aren't very long runs of consecutive existing OIDs. Again,
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* this is reasonable for system catalogs but less so for user tables.
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*
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* Since the OID is not immediately inserted into the table, there is a
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* race condition here; but a problem could occur only if someone else
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* managed to cycle through 2^32 OIDs and generate the same OID before we
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* finish inserting our row. This seems unlikely to be a problem. Note
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* that if we had to *commit* the row to end the race condition, the risk
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* would be rather higher; therefore we use SnapshotDirty in the test,
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* so that we will see uncommitted rows.
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*/
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Oid
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GetNewOid(Relation relation)
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{
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Oid oidIndex;
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/* If relation doesn't have OIDs at all, caller is confused */
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Assert(relation->rd_rel->relhasoids);
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/* In bootstrap mode, we don't have any indexes to use */
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if (IsBootstrapProcessingMode())
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return GetNewObjectId();
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/* The relcache will cache the identity of the OID index for us */
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oidIndex = RelationGetOidIndex(relation);
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/* If no OID index, just hand back the next OID counter value */
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if (!OidIsValid(oidIndex))
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{
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/*
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* System catalogs that have OIDs should *always* have a unique OID
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* index; we should only take this path for user tables. Give a
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* warning if it looks like somebody forgot an index.
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*/
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if (IsSystemRelation(relation))
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elog(WARNING, "generating possibly-non-unique OID for \"%s\"",
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RelationGetRelationName(relation));
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return GetNewObjectId();
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}
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/* Otherwise, use the index to find a nonconflicting OID */
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return GetNewOidWithIndex(relation, oidIndex, ObjectIdAttributeNumber);
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}
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/*
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* GetNewOidWithIndex
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* Guts of GetNewOid: use the supplied index
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*
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* This is exported separately because there are cases where we want to use
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* an index that will not be recognized by RelationGetOidIndex: TOAST tables
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* have indexes that are usable, but have multiple columns and are on
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* ordinary columns rather than a true OID column. This code will work
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* anyway, so long as the OID is the index's first column. The caller must
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* pass in the actual heap attnum of the OID column, however.
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*
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* Caller must have a suitable lock on the relation.
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*/
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Oid
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GetNewOidWithIndex(Relation relation, Oid indexId, AttrNumber oidcolumn)
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{
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Oid newOid;
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SnapshotData SnapshotDirty;
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SysScanDesc scan;
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ScanKeyData key;
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bool collides;
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InitDirtySnapshot(SnapshotDirty);
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/* Generate new OIDs until we find one not in the table */
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do
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{
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CHECK_FOR_INTERRUPTS();
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newOid = GetNewObjectId();
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ScanKeyInit(&key,
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oidcolumn,
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BTEqualStrategyNumber, F_OIDEQ,
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ObjectIdGetDatum(newOid));
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/* see notes above about using SnapshotDirty */
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scan = systable_beginscan(relation, indexId, true,
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&SnapshotDirty, 1, &key);
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collides = HeapTupleIsValid(systable_getnext(scan));
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systable_endscan(scan);
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} while (collides);
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return newOid;
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}
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/*
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* GetNewRelFileNode
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* Generate a new relfilenode number that is unique within the
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* database of the given tablespace.
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*
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* If the relfilenode will also be used as the relation's OID, pass the
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* opened pg_class catalog, and this routine will guarantee that the result
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* is also an unused OID within pg_class. If the result is to be used only
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* as a relfilenode for an existing relation, pass NULL for pg_class.
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*
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* As with GetNewOid, there is some theoretical risk of a race condition,
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* but it doesn't seem worth worrying about.
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*
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* Note: we don't support using this in bootstrap mode. All relations
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* created by bootstrap have preassigned OIDs, so there's no need.
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*/
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Oid
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GetNewRelFileNode(Oid reltablespace, Relation pg_class, char relpersistence)
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{
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RelFileNodeBackend rnode;
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char *rpath;
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int fd;
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bool collides;
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BackendId backend;
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switch (relpersistence)
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{
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case RELPERSISTENCE_TEMP:
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backend = BackendIdForTempRelations();
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break;
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case RELPERSISTENCE_UNLOGGED:
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case RELPERSISTENCE_PERMANENT:
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backend = InvalidBackendId;
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break;
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default:
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elog(ERROR, "invalid relpersistence: %c", relpersistence);
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return InvalidOid; /* placate compiler */
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}
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/* This logic should match RelationInitPhysicalAddr */
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rnode.node.spcNode = reltablespace ? reltablespace : MyDatabaseTableSpace;
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rnode.node.dbNode = (rnode.node.spcNode == GLOBALTABLESPACE_OID) ? InvalidOid : MyDatabaseId;
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/*
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* The relpath will vary based on the backend ID, so we must initialize
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* that properly here to make sure that any collisions based on filename
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* are properly detected.
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*/
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rnode.backend = backend;
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do
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{
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CHECK_FOR_INTERRUPTS();
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/* Generate the OID */
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if (pg_class)
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rnode.node.relNode = GetNewOid(pg_class);
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else
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rnode.node.relNode = GetNewObjectId();
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/* Check for existing file of same name */
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rpath = relpath(rnode, MAIN_FORKNUM);
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fd = BasicOpenFile(rpath, O_RDONLY | PG_BINARY, 0);
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if (fd >= 0)
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{
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/* definite collision */
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close(fd);
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collides = true;
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}
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else
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{
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/*
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* Here we have a little bit of a dilemma: if errno is something
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* other than ENOENT, should we declare a collision and loop? In
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* particular one might think this advisable for, say, EPERM.
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* However there really shouldn't be any unreadable files in a
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* tablespace directory, and if the EPERM is actually complaining
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* that we can't read the directory itself, we'd be in an infinite
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* loop. In practice it seems best to go ahead regardless of the
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* errno. If there is a colliding file we will get an smgr
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* failure when we attempt to create the new relation file.
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*/
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collides = false;
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}
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pfree(rpath);
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} while (collides);
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return rnode.node.relNode;
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}
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