On Thu, Apr 08, 2021 at 01:22:49PM +0800, Julien Rouhaud wrote: > Le jeu. 8 avr. 2021 à 13:17, Andres Freund <and...@anarazel.de> a écrit : > > > > > This - or something in the vicinity - seems to break running the > > regression tests with force_parallel_mode=regress. There's lots of > > differences like > > > > SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE > > "C"; > > query > > | calls | rows > > > > > > ------------------------------------------------------------------------------+-------+------ > > SELECT (i + $2 + $3)::INTEGER > > | 2 | 2 > > SELECT (i + $2)::INTEGER LIMIT $3 > > | 2 | 2 > > - SELECT PLUS_ONE($1) > > | 2 | 2 > > - SELECT PLUS_TWO($1) > > | 2 | 2 > > - SELECT pg_stat_statements_reset() > > | 1 | 1 > > + SELECT PLUS_ONE($1) > > | 4 | 4 > > + SELECT PLUS_TWO($1) > > | 4 | 4 > > + SELECT pg_stat_statements_reset(); > > oh, I think it's because parallel workers now have the queryid of the main > query. Probably ignoring parallel workers in the executor end hook will fix > the problem. I'll look at it as soon as I will be back home.
That was indeed the problem. I think the best is to entirely ignore parallel workers in pg_stat_statements, as done in attached patch, which fixes the regression tests with force_parallel_mode = regress.
>From 45885bee58ab98c33b8e75edec13e08851523444 Mon Sep 17 00:00:00 2001 From: Julien Rouhaud <julien.rouh...@free.fr> Date: Thu, 8 Apr 2021 13:59:43 +0800 Subject: [PATCH v1] Ignore parallel workers in pg_stat_statements. Oversight in 4f0b0966c8 which exposed queryid in parallel workers. Counters are aggregated by the main backend process so parallel workers would report duplicated activity, and could also report activity for the wrong entry as they are only aware of the top level queryid. Author: Julien Rouhaud Reported-by: Andres Freund Discussion: https://postgr.es/m/20210408051735.lfbdzun5zdlax...@alap3.anarazel.de --- contrib/pg_stat_statements/pg_stat_statements.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c index 52cba86196..78158ba7ce 100644 --- a/contrib/pg_stat_statements/pg_stat_statements.c +++ b/contrib/pg_stat_statements/pg_stat_statements.c @@ -47,6 +47,7 @@ #include <sys/stat.h> #include <unistd.h> +#include "access/parallel.h" #include "catalog/pg_authid.h" #include "common/hashfn.h" #include "executor/instrument.h" @@ -276,8 +277,9 @@ static bool pgss_save; /* whether to save stats across shutdown */ #define pgss_enabled(level) \ + (!IsParallelWorker() && \ (pgss_track == PGSS_TRACK_ALL || \ - (pgss_track == PGSS_TRACK_TOP && (level) == 0)) + (pgss_track == PGSS_TRACK_TOP && (level) == 0))) #define record_gc_qtexts() \ do { \ -- 2.30.1
