Hi, On 2022-11-29 15:42:45 +0900, Kyotaro Horiguchi wrote: > At Mon, 28 Nov 2022 14:01:30 +0530, vignesh C <vignes...@gmail.com> wrote in > > Hi, > > > > While reviewing/testing one of the patches I found the following Assert: > > #0 0x000055c6312ba639 in pgstat_unlink_relation (rel=0x7fb73bcbac58) > > at pgstat_relation.c:161 > > #1 0x000055c6312bbb5a in pgstat_relation_delete_pending_cb > > (entry_ref=0x55c6335563a8) at pgstat_relation.c:839 > > #2 0x000055c6312b72bc in pgstat_delete_pending_entry > > (entry_ref=0x55c6335563a8) at pgstat.c:1124 > > #3 0x000055c6312be3f1 in pgstat_release_entry_ref (key=..., > > entry_ref=0x55c6335563a8, discard_pending=true) at pgstat_shmem.c:523 > > #4 0x000055c6312bee9a in pgstat_drop_entry > > (kind=PGSTAT_KIND_RELATION, dboid=5, objoid=40960) at > > pgstat_shmem.c:867 > > #5 0x000055c6312c034a in AtEOXact_PgStat_DroppedStats > > (xact_state=0x55c6334baac8, isCommit=false) at pgstat_xact.c:97 > > #6 0x000055c6312c0240 in AtEOXact_PgStat (isCommit=false, > > parallel=false) at pgstat_xact.c:55 > > #7 0x000055c630df8bee in AbortTransaction () at xact.c:2861 > > #8 0x000055c630df94fd in AbortCurrentTransaction () at xact.c:3352 > > > > I could reproduce this issue with the following steps: > > create table t1(c1 int); > > BEGIN; > > CREATE TABLE t (c1 int); > > CREATE RULE "_RETURN" AS ON SELECT TO t DO INSTEAD SELECT * FROM t1; > > CREATE RULE "_RETURN" AS ON SELECT TO t DO INSTEAD SELECT * FROM t1; > > Good catch! > > AtEOXact_PgStat_DroppedStats() visits a relation that has been dropped > then wiped (when CLOBBER_FREED_MEMORY) by AtEOXact_RelationCache() > called just before. Since the relcache content directly pointed from > stats module is lost in this case, the stats side cannot defend itself > from this. > > Perhaps RelationDestroyRelation() need to do pgstat_drop_entry() or > AtEOXact_PgStat_DroppedStats() should be called before > AtEOXact_RelationCache(). the latter of which is simpler. I think we > need to test this case, too.
This doesn't strike me as the right fix. What do you think about my patch at https://postgr.es/m/20221128210908.hyffmljjylj447nu%40awork3.anarazel.de , leaving the quibbles around error handling aside? Afaict it fixes the issue. Greetings, Andres Freund
