From aedd3d4dbd6ecf73a4045e302b68cc498d0e6b58 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 7 Dec 2018 12:12:00 -0500 Subject: [PATCH] Fix misapplication of pgstat_count_truncate to wrong relation. The stanza of ExecuteTruncate[Guts] that truncates a target table's toast relation re-used the loop local variable "rel" to reference the toast rel. This was safe enough when written, but commit d42358efb added code below that that supposed "rel" still pointed to the parent table. Therefore, the stats counter update was applied to the wrong relcache entry (the toast rel not the user rel); and if we were unlucky and that relcache entry had been flushed during reindex_relation, very bad things could ensue. (I'm surprised that CLOBBER_CACHE_ALWAYS testing hasn't found this. I'm even more surprised that the problem wasn't detected during the development of d42358efb; it must not have been tested in any case with a toast table, as the incorrect stats counts are very obvious.) To fix, replace use of "rel" in that code branch with a more local variable. Adjust test cases added by d42358efb so that some of them use tables with toast tables. Per bug #15540 from Pan Bian. Back-patch to 9.5 where d42358efb came in. Discussion: https://postgr.es/m/15540-01078812338195c0@postgresql.org --- src/backend/commands/tablecmds.c | 15 +++++++++------ src/test/regress/expected/stats.out | 4 ++-- src/test/regress/sql/stats.sql | 4 ++-- 3 files changed, 13 insertions(+), 10 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 82312686c4..20c6a09b41 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -1600,19 +1600,22 @@ ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_logged, heap_create_init_fork(rel); heap_relid = RelationGetRelid(rel); - toast_relid = rel->rd_rel->reltoastrelid; /* * The same for the toast table, if any. */ + toast_relid = rel->rd_rel->reltoastrelid; if (OidIsValid(toast_relid)) { - rel = relation_open(toast_relid, AccessExclusiveLock); - RelationSetNewRelfilenode(rel, rel->rd_rel->relpersistence, + Relation toastrel = relation_open(toast_relid, + AccessExclusiveLock); + + RelationSetNewRelfilenode(toastrel, + toastrel->rd_rel->relpersistence, RecentXmin, minmulti); - if (rel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED) - heap_create_init_fork(rel); - heap_close(rel, NoLock); + if (toastrel->rd_rel->relpersistence == RELPERSISTENCE_UNLOGGED) + heap_create_init_fork(toastrel); + heap_close(toastrel, NoLock); } /* diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out index 991c287b11..b01e58b98c 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -79,9 +79,9 @@ end $$ language plpgsql; -- test effects of TRUNCATE on n_live_tup/n_dead_tup counters CREATE TABLE trunc_stats_test(id serial); -CREATE TABLE trunc_stats_test1(id serial); +CREATE TABLE trunc_stats_test1(id serial, stuff text); CREATE TABLE trunc_stats_test2(id serial); -CREATE TABLE trunc_stats_test3(id serial); +CREATE TABLE trunc_stats_test3(id serial, stuff text); CREATE TABLE trunc_stats_test4(id serial); -- check that n_live_tup is reset to 0 after truncate INSERT INTO trunc_stats_test DEFAULT VALUES; diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index 2be7dde834..feaaee6326 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -79,9 +79,9 @@ $$ language plpgsql; -- test effects of TRUNCATE on n_live_tup/n_dead_tup counters CREATE TABLE trunc_stats_test(id serial); -CREATE TABLE trunc_stats_test1(id serial); +CREATE TABLE trunc_stats_test1(id serial, stuff text); CREATE TABLE trunc_stats_test2(id serial); -CREATE TABLE trunc_stats_test3(id serial); +CREATE TABLE trunc_stats_test3(id serial, stuff text); CREATE TABLE trunc_stats_test4(id serial); -- check that n_live_tup is reset to 0 after truncate