From cafcc3ad0ed324993211b0dce09362aad3165146 Mon Sep 17 00:00:00 2001 From: Noah Misch Date: Tue, 24 Sep 2024 15:25:18 -0700 Subject: For inplace update durability, make heap_update() callers wait. The previous commit fixed some ways of losing an inplace update. It remained possible to lose one when a backend working toward a heap_update() copied a tuple into memory just before inplace update of that tuple. In catalogs eligible for inplace update, use LOCKTAG_TUPLE to govern admission to the steps of copying an old tuple, modifying it, and issuing heap_update(). This includes MERGE commands. To avoid changing most of the pg_class DDL, don't require LOCKTAG_TUPLE when holding a relation lock sufficient to exclude inplace updaters. Back-patch to v12 (all supported versions). In v13 and v12, "UPDATE pg_class" or "UPDATE pg_database" can still lose an inplace update. The v14+ UPDATE fix needs commit 86dc90056dfdbd9d1b891718d2e5614e3e432f35, and it wasn't worth reimplementing that fix without such infrastructure. Reviewed by Nitin Motiani and (in earlier versions) Heikki Linnakangas. Discussion: https://postgr.es/m/20231027214946.79.nmisch@google.com --- src/backend/executor/execReplication.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'src/backend/executor/execReplication.c') diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c index 72ce9fa1a29..050bab302dd 100644 --- a/src/backend/executor/execReplication.c +++ b/src/backend/executor/execReplication.c @@ -19,6 +19,7 @@ #include "access/tableam.h" #include "access/transam.h" #include "access/xact.h" +#include "catalog/catalog.h" #include "commands/trigger.h" #include "executor/executor.h" #include "executor/nodeModifyTable.h" @@ -471,8 +472,12 @@ ExecSimpleRelationUpdate(EState *estate, EPQState *epqstate, Relation rel = resultRelInfo->ri_RelationDesc; ItemPointer tid = &(searchslot->tts_tid); - /* For now we support only tables. */ + /* + * We support only non-system tables, with + * check_publication_add_relation() accountable. + */ Assert(rel->rd_rel->relkind == RELKIND_RELATION); + Assert(!IsCatalogRelation(rel)); CheckCmdReplicaIdentity(rel, CMD_UPDATE); -- cgit v1.2.3