From 69f3e4f063a956f429ee0dbdbd213dcad8242613 Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Wed, 28 Jan 2026 07:53:13 +0000 Subject: [PATCH v6 3/5] Add GUC to specify non-transactional statistics flush interval Adding pgstat_flush_interval, a new GUC to set the interval between flushes of non-transactional statistics. --- doc/src/sgml/config.sgml | 34 +++++++++++++++++++ src/backend/utils/activity/pgstat.c | 16 +++++++++ src/backend/utils/misc/guc_parameters.dat | 10 ++++++ src/backend/utils/misc/postgresql.conf.sample | 1 + src/include/pgstat.h | 6 ++-- src/include/utils/guc_hooks.h | 1 + 6 files changed, 64 insertions(+), 4 deletions(-) 59.1% doc/src/sgml/ 14.2% src/backend/utils/activity/ 14.5% src/backend/utils/misc/ 12.0% src/include/ diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index f1af1505cf3..20666679f90 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -8871,6 +8871,40 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; + + stats_flush_interval (integer) + + stats_flush_interval configuration parameter + + + + + Sets the interval at which statistics that can be updated while a + transaction is still running are made visible. These include, for example, + WAL activity and I/O operations. + Such statistics are refreshed at the specified interval and can be observed + during active transactions in monitoring views such as + pg_stat_io + and + pg_stat_wal. + Other statistics are only made visible at transaction end and are not + affected by this setting. + If the value is specified without a unit, milliseconds are assumed. + The default is 10 seconds (10s), which is generally + the smallest practical value for long-running transactions. + + + + This parameter does not affect statistics that are only reported at + transaction end, such as the columns of pg_stat_all_tables + (for example, n_tup_ins, n_tup_upd, + and n_tup_del). These statistics are always + flushed at the end of a transaction. + + + + + diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c index 411b65aae3e..79eb59b5625 100644 --- a/src/backend/utils/activity/pgstat.c +++ b/src/backend/utils/activity/pgstat.c @@ -123,6 +123,8 @@ * ---------- */ +/* minimum interval non-forced stats flushes.*/ +#define PGSTAT_MIN_INTERVAL 1000 /* how long until to block flushing pending stats updates */ #define PGSTAT_MAX_INTERVAL 60000 /* when to call pgstat_report_stat() again, even when idle */ @@ -203,6 +205,7 @@ static inline bool pgstat_is_kind_valid(PgStat_Kind kind); bool pgstat_track_counts = false; int pgstat_fetch_consistency = PGSTAT_FETCH_CONSISTENCY_CACHE; +int pgstat_flush_interval = 10000; /* ---------- @@ -2164,6 +2167,19 @@ assign_stats_fetch_consistency(int newval, void *extra) force_stats_snapshot_clear = true; } +/* + * GUC assign_hook for stats_flush_interval. + */ +void +assign_stats_flush_interval(int newval, void *extra) +{ + if (get_timeout_active(ANYTIME_STATS_UPDATE_TIMEOUT)) + { + disable_timeout(ANYTIME_STATS_UPDATE_TIMEOUT, false); + enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT, newval); + } +} + /* * Flushes only FLUSH_ANYTIME stats using non-blocking locks. Transactional * stats (FLUSH_AT_TXN_BOUNDARY) remain pending until transaction boundary. diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat index c1f1603cd39..fc0e4259b36 100644 --- a/src/backend/utils/misc/guc_parameters.dat +++ b/src/backend/utils/misc/guc_parameters.dat @@ -2789,6 +2789,16 @@ assign_hook => 'assign_stats_fetch_consistency', }, +{ name => 'stats_flush_interval', type => 'int', context => 'PGC_USERSET', group => 'STATS_CUMULATIVE', + short_desc => 'Sets the interval between flushes of non-transactional statistics.', + flags => 'GUC_UNIT_MS', + variable => 'pgstat_flush_interval', + boot_val => '10000', + min => '1000', + max => 'INT_MAX', + assign_hook => 'assign_stats_flush_interval' +}, + { name => 'subtransaction_buffers', type => 'int', context => 'PGC_POSTMASTER', group => 'RESOURCES_MEM', short_desc => 'Sets the size of the dedicated buffer pool used for the subtransaction cache.', long_desc => '0 means use a fraction of "shared_buffers".', diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 1ae594af843..3f998a0bea0 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -673,6 +673,7 @@ #track_wal_io_timing = off #track_functions = none # none, pl, all #stats_fetch_consistency = cache # cache, none, snapshot +#stats_flush_interval = 10s # in milliseconds # - Monitoring - diff --git a/src/include/pgstat.h b/src/include/pgstat.h index b340a680614..ef856dbf55b 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -35,9 +35,6 @@ /* Default directory to store temporary statistics data in */ #define PG_STAT_TMP_DIR "pg_stat_tmp" -/* Minimum interval non-forced stats flushes */ -#define PGSTAT_MIN_INTERVAL 1000 - /* Values for track_functions GUC variable --- order is significant! */ typedef enum TrackFunctionsLevel { @@ -548,7 +545,7 @@ extern void pgstat_force_next_flush(void); #define pgstat_schedule_anytime_update() \ do { \ if (IsUnderPostmaster && !get_timeout_active(ANYTIME_STATS_UPDATE_TIMEOUT)) \ - enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT, PGSTAT_MIN_INTERVAL); \ + enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT, pgstat_flush_interval); \ } while (0) extern void pgstat_reset_counters(void); @@ -828,6 +825,7 @@ extern PgStat_WalStats *pgstat_fetch_stat_wal(void); extern PGDLLIMPORT bool pgstat_track_counts; extern PGDLLIMPORT int pgstat_track_functions; extern PGDLLIMPORT int pgstat_fetch_consistency; +extern PGDLLIMPORT int pgstat_flush_interval; /* diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h index b6ecb0e769f..3a2ae6c41cd 100644 --- a/src/include/utils/guc_hooks.h +++ b/src/include/utils/guc_hooks.h @@ -132,6 +132,7 @@ extern bool check_session_authorization(char **newval, void **extra, GucSource s extern void assign_session_authorization(const char *newval, void *extra); extern void assign_session_replication_role(int newval, void *extra); extern void assign_stats_fetch_consistency(int newval, void *extra); +extern void assign_stats_flush_interval(int newval, void *extra); extern bool check_ssl(bool *newval, void **extra, GucSource source); extern bool check_stage_log_stats(bool *newval, void **extra, GucSource source); extern bool check_standard_conforming_strings(bool *newval, void **extra, -- 2.34.1