From 295c963b9dc7e94fc4967600eea8238fcb017340 Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Fri, 20 Jun 2025 12:11:21 +0000 Subject: [PATCH v1 3/4] Add the pg_stat_wait_event view This new view reports wait events statistics (for non custom wait event). This commit also adds documentation and regression tests. XXX: Bump catalog version --- doc/src/sgml/monitoring.sgml | 84 ++++++++++++++++++++++++++++ src/backend/catalog/system_views.sql | 8 +++ src/backend/utils/adt/pgstatfuncs.c | 51 +++++++++++++++++ src/include/catalog/pg_proc.dat | 9 +++ src/test/regress/expected/rules.out | 5 ++ src/test/regress/expected/stats.out | 48 ++++++++++++++++ src/test/regress/sql/stats.sql | 22 ++++++++ 7 files changed, 227 insertions(+) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 4265a22d4de..4299dd3ffb2 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -518,6 +518,14 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser + + pg_stat_wait_eventpg_stat_wait_event + One row per each non custom wait event, showing statistics about wait event activity. See + + pg_stat_wait_event for details. + + + pg_stat_walpg_stat_wal One row only, showing statistics about WAL activity. See @@ -4822,6 +4830,76 @@ description | Waiting for a newly initialized WAL file to reach durable storage + + <structname>pg_stat_wait_event</structname> + + + pg_stat_wait_event + + + + The pg_stat_wait_event view will contain + one row for each non custom wait event, showing statistics about that wait + event. + + + + <structname>pg_stat_wait_event</structname> View + + + + + Column Type + + + Description + + + + + + + + type text + + + Wait event type + + + + + + name text + + + Wait event name + + + + + + counts bigint + + + Number of times waiting on this wait event + + + + + + stats_reset timestamp with time zone + + + Time at which these statistics were last reset + + + + + +
+ + + Statistics Functions @@ -5054,6 +5132,12 @@ description | Waiting for a newly initialized WAL file to reach durable storage pg_stat_slru view. + + + wait_event: Reset all the counters shown in the + pg_stat_wait_event view. + + wal: Reset all the counters shown in the diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index 08f780a2e63..b3e93723964 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -942,6 +942,14 @@ CREATE VIEW pg_stat_slru AS s.stats_reset FROM pg_stat_get_slru() s; +CREATE VIEW pg_stat_wait_event AS + SELECT + s.type, + s.name, + s.counts, + s.stats_reset + FROM pg_stat_get_wait_event() s; + CREATE VIEW pg_stat_wal_receiver AS SELECT s.pid, diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index 1c12ddbae49..cfa6aefd95e 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -1743,6 +1743,54 @@ pg_stat_get_slru(PG_FUNCTION_ARGS) return (Datum) 0; } +/* + * Returns statistics of wait events. + */ +Datum +pg_stat_get_wait_event(PG_FUNCTION_ARGS) +{ +#define PG_STAT_GET_WAIT_EVENTS_COLS 4 + ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo; + int i, + j; + PgStat_WaitEvent *stats; + + InitMaterializedSRF(fcinfo, 0); + + /* request wait event stats from the cumulative stats system */ + stats = pgstat_fetch_stat_wait_event(); + + for (i = 0; i < NB_WAITCLASSTABLE_ENTRIES; i++) + { + /* for each row */ + Datum values[PG_STAT_GET_WAIT_EVENTS_COLS] = {0}; + bool nulls[PG_STAT_GET_WAIT_EVENTS_COLS] = {0}; + WaitClassTableEntry *class = &WaitClassTable[i]; + int numWaitEvents; + + numWaitEvents = class->numberOfEvents; + + for (j = 0; j < numWaitEvents; j++) + { + const char *name; + + name = get_wait_event_name_from_index(class->offSet + j); + + if (!name) + continue; + + values[0] = PointerGetDatum(cstring_to_text(class->className)); + values[1] = PointerGetDatum(cstring_to_text(name)); + values[2] = Int64GetDatum(stats->counts[class->offSet + j]); + values[3] = TimestampTzGetDatum(stats->stat_reset_timestamp); + + tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls); + } + } + + return (Datum) 0; +} + #define PG_STAT_GET_XACT_RELENTRY_INT64(stat) \ Datum \ CppConcat(pg_stat_get_xact_,stat)(PG_FUNCTION_ARGS) \ @@ -1882,6 +1930,7 @@ pg_stat_reset_shared(PG_FUNCTION_ARGS) pgstat_reset_of_kind(PGSTAT_KIND_IO); XLogPrefetchResetStats(); pgstat_reset_of_kind(PGSTAT_KIND_SLRU); + pgstat_reset_of_kind(PGSTAT_KIND_WAIT_EVENT); pgstat_reset_of_kind(PGSTAT_KIND_WAL); PG_RETURN_VOID(); @@ -1901,6 +1950,8 @@ pg_stat_reset_shared(PG_FUNCTION_ARGS) XLogPrefetchResetStats(); else if (strcmp(target, "slru") == 0) pgstat_reset_of_kind(PGSTAT_KIND_SLRU); + else if (strcmp(target, "wait_event") == 0) + pgstat_reset_of_kind(PGSTAT_KIND_WAIT_EVENT); else if (strcmp(target, "wal") == 0) pgstat_reset_of_kind(PGSTAT_KIND_WAL); else diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index fb4f7f50350..6ecea50a88c 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -6041,6 +6041,15 @@ proargnames => '{name,blks_zeroed,blks_hit,blks_read,blks_written,blks_exists,flushes,truncates,stats_reset}', prosrc => 'pg_stat_get_slru' }, +{ oid => '8962', descr => 'statistics: information about wait events', + proname => 'pg_stat_get_wait_event', prorows => '300', proisstrict => 'f', + proretset => 't', provolatile => 's', proparallel => 'r', + prorettype => 'record', proargtypes => '', + proallargtypes => '{text,text,int8,timestamptz}', + proargmodes => '{o,o,o,o}', + proargnames => '{type,name,counts,stats_reset}', + prosrc => 'pg_stat_get_wait_event' }, + { oid => '2978', descr => 'statistics: number of function calls', proname => 'pg_stat_get_function_calls', provolatile => 's', proparallel => 'r', prorettype => 'int8', proargtypes => 'oid', diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 6cf828ca8d0..e5f8938a176 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -2277,6 +2277,11 @@ pg_stat_user_tables| SELECT relid, total_autoanalyze_time FROM pg_stat_all_tables WHERE ((schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (schemaname !~ '^pg_toast'::text)); +pg_stat_wait_event| SELECT type, + name, + counts, + stats_reset + FROM pg_stat_get_wait_event() s(type, name, counts, stats_reset); pg_stat_wal| SELECT wal_records, wal_fpi, wal_bytes, diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out index 776f1ad0e53..26d72dda3f1 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -236,6 +236,54 @@ FROM prevstats AS pr; (1 row) COMMIT; +---- +-- Basic tests for wait events statistics +--- +-- ensure there is no wait events missing in pg_stat_wait_event +select count(1) > 0 from pg_stat_wait_event + where name not in (select name from pg_wait_events + where type <> 'InjectionPoint' or type <> 'Extension') + and type <> 'Extension'; + ?column? +---------- + f +(1 row) + +-- Test that reset_shared with wait_event specified as the stats type works +SELECT count(1) AS counts_wait_event FROM pg_stat_wait_event WHERE counts > 0 \gset +SELECT :counts_wait_event > 0; + ?column? +---------- + t +(1 row) + +SELECT pg_stat_reset_shared('wait_event'); + pg_stat_reset_shared +---------------------- + +(1 row) + +SELECT count(1) < :counts_wait_event FROM pg_stat_wait_event WHERE counts > 0; + ?column? +---------- + t +(1 row) + +-- Test wait event counters are incremented +CREATE TABLE wait_event_stats_test(id serial); +INSERT INTO wait_event_stats_test DEFAULT VALUES; +SELECT pg_stat_force_next_flush(); + pg_stat_force_next_flush +-------------------------- + +(1 row) + +SELECT counts > 0 FROM pg_stat_wait_event WHERE name = 'WalWrite' and type = 'IO'; + ?column? +---------- + t +(1 row) + ---- -- Basic tests for track_functions --- diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index 232ab8db8fa..0ea887a45fd 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -132,6 +132,28 @@ FROM prevstats AS pr; COMMIT; +---- +-- Basic tests for wait events statistics +--- + +-- ensure there is no wait events missing in pg_stat_wait_event +select count(1) > 0 from pg_stat_wait_event + where name not in (select name from pg_wait_events + where type <> 'InjectionPoint' or type <> 'Extension') + and type <> 'Extension'; + +-- Test that reset_shared with wait_event specified as the stats type works +SELECT count(1) AS counts_wait_event FROM pg_stat_wait_event WHERE counts > 0 \gset +SELECT :counts_wait_event > 0; +SELECT pg_stat_reset_shared('wait_event'); +SELECT count(1) < :counts_wait_event FROM pg_stat_wait_event WHERE counts > 0; + +-- Test wait event counters are incremented +CREATE TABLE wait_event_stats_test(id serial); +INSERT INTO wait_event_stats_test DEFAULT VALUES; +SELECT pg_stat_force_next_flush(); +SELECT counts > 0 FROM pg_stat_wait_event WHERE name = 'WalWrite' and type = 'IO'; + ---- -- Basic tests for track_functions --- -- 2.34.1