Fix stats_fetch_consistency with stats for fixed-numbered objects

michaelpq · michaelpq · commit 235c09efbb30 · 2024-02-01T17:12:50.000+09:00
This impacts the statistics retrieved in transactions for the following views when updating the value of stats_fetch_consistency, leading to behaviors contrary to what is documented since 6059946 as an update of this parameter should discard all statistics snapshot data: - pg_stat_archiver - pg_stat_bgwriter - pg_stat_checkpointer - pg_stat_io - pg_stat_slru - pg_stat_wal For example, updating stats_fetch_consistency from "snapshot" to "cache" in a transaction did not re-fetch any fresh data, using data cached from the time when "snapshot" was in use. Author: Shinya Kato Discussion: https://postgr.es/m/d77fc5190d4dbe1738d77231488e768b@oss.nttdata.com Backpatch-through: 15
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
@@ -943,6 +943,9 @@ pgstat_snapshot_fixed(PgStat_Kind kind)
 	Assert(pgstat_is_kind_valid(kind));
 	Assert(pgstat_get_kind_info(kind)->fixed_amount);
 
+	if (force_stats_snapshot_clear)
+		pgstat_clear_snapshot();
+
 	if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT)
 		pgstat_build_snapshot();
 	else
