From 97f87ae42e339d5d30d30c35f80ee9d7db75dca6 Mon Sep 17 00:00:00 2001 From: Tristan Partin Date: Mon, 6 Jul 2026 22:30:12 +0000 Subject: [PATCH v1] Add entry_size column to pg_stat_kind_info pg_stat_kind_info lacked a way to inspect the size of the statistics data payload for each registered kind. The column represents PgStat_KindInfo::shared_data_len, which is the size of the serializable statistics data payload, excluding shared memory wrapper overhead such as locking structures and hash table bookkeeping. Signed-off-by: Tristan Partin --- doc/src/sgml/monitoring.sgml | 13 +++++++ src/backend/catalog/system_views.sql | 3 +- src/backend/utils/activity/pgstat_kind.c | 4 ++- src/include/catalog/pg_proc.dat | 6 ++-- .../test_custom_stats/t/001_custom_stats.pl | 8 ++--- src/test/regress/expected/rules.out | 5 +-- src/test/regress/expected/stats.out | 34 +++++++++---------- src/test/regress/sql/stats.sql | 4 +-- 8 files changed, 47 insertions(+), 30 deletions(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 12b9ee20d4a..76b43d0b38c 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -3426,6 +3426,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage + + + + + entry_size bigint + + + Size of the statistics data for each entry of this kind in bytes. This + reflects the serializable statistics payload only, and does not include + any shared memory overhead. + + + diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index 6c1c5545cb5..a1196be6e54 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -1290,7 +1290,8 @@ CREATE VIEW pg_stat_kind_info AS k.fixed_amount, k.accessed_across_databases, k.write_to_file, - k.entry_count + k.entry_count, + k.entry_size FROM pg_stat_get_kind_info() k; CREATE VIEW pg_stat_wal AS diff --git a/src/backend/utils/activity/pgstat_kind.c b/src/backend/utils/activity/pgstat_kind.c index 6c53b7e49bf..e9e636b34aa 100644 --- a/src/backend/utils/activity/pgstat_kind.c +++ b/src/backend/utils/activity/pgstat_kind.c @@ -31,7 +31,7 @@ Datum pg_stat_get_kind_info(PG_FUNCTION_ARGS) { -#define PG_STAT_KIND_INFO_COLS 7 +#define PG_STAT_KIND_INFO_COLS 8 ReturnSetInfo *rsinfo; InitMaterializedSRF(fcinfo, 0); @@ -64,6 +64,8 @@ pg_stat_get_kind_info(PG_FUNCTION_ARGS) else nulls[6] = true; + values[7] = Int64GetDatum((int64) pgstat_get_entry_len(kind)); + tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls); } diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 3cb84359adf..89d13d01184 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -6081,9 +6081,9 @@ { oid => '8683', descr => 'statistics: information about statistics kinds', proname => 'pg_stat_get_kind_info', prorows => '20', proretset => 't', provolatile => 'v', proparallel => 'r', prorettype => 'record', - proargtypes => '', proallargtypes => '{int4,text,bool,bool,bool,bool,int8}', - proargmodes => '{o,o,o,o,o,o,o}', - proargnames => '{id,name,builtin,fixed_amount,accessed_across_databases,write_to_file,entry_count}', + proargtypes => '', proallargtypes => '{int4,text,bool,bool,bool,bool,int8,int8}', + proargmodes => '{o,o,o,o,o,o,o,o}', + proargnames => '{id,name,builtin,fixed_amount,accessed_across_databases,write_to_file,entry_count,entry_size}', prosrc => 'pg_stat_get_kind_info' }, { oid => '1136', descr => 'statistics: information about WAL activity', diff --git a/src/test/modules/test_custom_stats/t/001_custom_stats.pl b/src/test/modules/test_custom_stats/t/001_custom_stats.pl index 69f2284229e..ee291f4ac13 100644 --- a/src/test/modules/test_custom_stats/t/001_custom_stats.pl +++ b/src/test/modules/test_custom_stats/t/001_custom_stats.pl @@ -31,12 +31,12 @@ my $result = $node->safe_psql( 'postgres', q(SELECT id, name, builtin, fixed_amount, accessed_across_databases, - write_to_file + write_to_file, entry_size > 0 FROM pg_stat_kind_info WHERE name LIKE 'test_custom%' ORDER BY id)); -is( $result, - qq{25|test_custom_var_stats|f|f|t|t -26|test_custom_fixed_stats|f|t|f|t}, +is($result, + qq{25|test_custom_var_stats|f|f|t|t|t +26|test_custom_fixed_stats|f|t|f|t|t}, "custom stats kinds visible in pg_stat_kind_info"); # Create entries for variable-sized stats. diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 39905c2de14..f623b06910a 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -1973,8 +1973,9 @@ pg_stat_kind_info| SELECT id, fixed_amount, accessed_across_databases, write_to_file, - entry_count - FROM pg_stat_get_kind_info() k(id, name, builtin, fixed_amount, accessed_across_databases, write_to_file, entry_count); + entry_count, + entry_size + FROM pg_stat_get_kind_info() k(id, name, builtin, fixed_amount, accessed_across_databases, write_to_file, entry_count, entry_size); pg_stat_lock| SELECT locktype, waits, wait_time, diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out index 03cbc1cdef5..c8479c0faf7 100644 --- a/src/test/regress/expected/stats.out +++ b/src/test/regress/expected/stats.out @@ -114,26 +114,26 @@ walwriter|wal|normal (95 rows) \a -- List of registered statistics kinds. -SELECT id, name, fixed_amount, - accessed_across_databases AS across_db, write_to_file +SELECT id, name, fixed_amount, accessed_across_databases AS across_db, + write_to_file, entry_size > 0 AS has_entry_size FROM pg_stat_kind_info WHERE builtin ORDER BY id; - id | name | fixed_amount | across_db | write_to_file -----+--------------+--------------+-----------+--------------- - 1 | database | f | t | t - 2 | relation | f | f | t - 3 | function | f | f | t - 4 | replslot | f | t | t - 5 | subscription | f | t | t - 6 | backend | f | t | f - 7 | archiver | t | f | t - 8 | bgwriter | t | f | t - 9 | checkpointer | t | f | t - 10 | io | t | f | t - 11 | lock | t | f | t - 12 | slru | t | f | t - 13 | wal | t | f | t + id | name | fixed_amount | across_db | write_to_file | has_entry_size +----+--------------+--------------+-----------+---------------+---------------- + 1 | database | f | t | t | t + 2 | relation | f | f | t | t + 3 | function | f | f | t | t + 4 | replslot | f | t | t | t + 5 | subscription | f | t | t | t + 6 | backend | f | t | f | t + 7 | archiver | t | f | t | t + 8 | bgwriter | t | f | t | t + 9 | checkpointer | t | f | t | t + 10 | io | t | f | t | t + 11 | lock | t | f | t | t + 12 | slru | t | f | t | t + 13 | wal | t | f | t | t (13 rows) -- ensure that both seqscan and indexscan plans are allowed diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql index 4c265d1245c..554e6068aa5 100644 --- a/src/test/regress/sql/stats.sql +++ b/src/test/regress/sql/stats.sql @@ -15,8 +15,8 @@ SELECT backend_type, object, context FROM pg_stat_io \a -- List of registered statistics kinds. -SELECT id, name, fixed_amount, - accessed_across_databases AS across_db, write_to_file +SELECT id, name, fixed_amount, accessed_across_databases AS across_db, + write_to_file, entry_size > 0 AS has_entry_size FROM pg_stat_kind_info WHERE builtin ORDER BY id; -- Tristan Partin https://tristan.partin.io