From 078303f79b513ef8f50fdf2a95181c61519e4559 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 1894485901..bc83a9a4a0 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -1225,19 +1225,22 @@ ExecuteTruncate(TruncateStmt *stmt) 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 4f397a3280..2a1d1e24ac 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -80,9 +80,9 @@ end $$ language plpgsql; -- test effects of TRUNCATE on n_live_tup/n_dead_tup counters CREATE TABLE trunc_stats_test(id serial); -CREATE TABLE trunc_stats_test1(id serial); +CREATE TABLE trunc_stats_test1(id serial, stuff text); CREATE TABLE trunc_stats_test2(id serial); -CREATE TABLE trunc_stats_test3(id serial); +CREATE TABLE trunc_stats_test3(id serial, stuff text); CREATE TABLE trunc_stats_test4(id serial); -- check that n_live_tup is reset to 0 after truncate INSERT INTO trunc_stats_test DEFAULT VALUES; diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index 521dc4d6a3..bb116185c7 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -76,9 +76,9 @@ $$ 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