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| author | Noah Misch <noah@leadboat.com> | 2024-09-24 15:25:18 -0700 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2024-09-24 15:25:18 -0700 |
| commit | aac2c9b4fde889d13f859c233c2523345e72d32b (patch) | |
| tree | 65d5e1b73059d4c423dee459bcf58bc0c47b8a9a /src/backend/utils/cache/relcache.c | |
| parent | a07e03fd8fa7daf4d1356f7cb501ffe784ea6257 (diff) | |
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
Diffstat (limited to 'src/backend/utils/cache/relcache.c')
| -rw-r--r-- | src/backend/utils/cache/relcache.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c index 5b6b7b809c0..c326f687eb4 100644 --- a/src/backend/utils/cache/relcache.c +++ b/src/backend/utils/cache/relcache.c @@ -3768,6 +3768,7 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) { RelFileNumber newrelfilenumber; Relation pg_class; + ItemPointerData otid; HeapTuple tuple; Form_pg_class classform; MultiXactId minmulti = InvalidMultiXactId; @@ -3810,11 +3811,12 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) */ pg_class = table_open(RelationRelationId, RowExclusiveLock); - tuple = SearchSysCacheCopy1(RELOID, - ObjectIdGetDatum(RelationGetRelid(relation))); + tuple = SearchSysCacheLockedCopy1(RELOID, + ObjectIdGetDatum(RelationGetRelid(relation))); if (!HeapTupleIsValid(tuple)) elog(ERROR, "could not find tuple for relation %u", RelationGetRelid(relation)); + otid = tuple->t_self; classform = (Form_pg_class) GETSTRUCT(tuple); /* @@ -3934,9 +3936,10 @@ RelationSetNewRelfilenumber(Relation relation, char persistence) classform->relminmxid = minmulti; classform->relpersistence = persistence; - CatalogTupleUpdate(pg_class, &tuple->t_self, tuple); + CatalogTupleUpdate(pg_class, &otid, tuple); } + UnlockTuple(pg_class, &otid, InplaceUpdateTupleLock); heap_freetuple(tuple); table_close(pg_class, RowExclusiveLock); |