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help / color / mirror / Atom feedFrom: Bertrand Drouvot <[email protected]>
Subject: [PATCH v5 2/4] Add GUC to specify non-transactional statistics flush interval
Date: Wed, 28 Jan 2026 07:53:13 +0000
Adding pgstat_flush_interval, a new GUC to set the interval between flushes of
non-transactional statistics.
---
doc/src/sgml/config.sgml | 32 +++++++++++++++++++
src/backend/access/transam/xlog.c | 4 +--
src/backend/utils/activity/pgstat.c | 16 +++++++++-
src/backend/utils/activity/pgstat_backend.c | 4 +--
src/backend/utils/activity/pgstat_io.c | 2 +-
src/backend/utils/activity/pgstat_slru.c | 2 +-
src/backend/utils/misc/guc_parameters.dat | 10 ++++++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/include/pgstat.h | 1 +
src/include/utils/guc_hooks.h | 1 +
10 files changed, 66 insertions(+), 7 deletions(-)
45.9% doc/src/sgml/
6.5% src/backend/access/transam/
31.8% src/backend/utils/activity/
12.3% src/backend/utils/misc/
3.2% src/include/
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 5560b95ee60..3136816a933 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -8834,6 +8834,38 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
</listitem>
</varlistentry>
+ <varlistentry id="guc-stats-flush-interval" xreflabel="stats_flush_interval">
+ <term><varname>stats_flush_interval</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>stats_flush_interval</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Sets the interval at which non-transactional statistics are made visible
+ during running transactions. Non-transactional statistics include, for
+ example, WAL activity and I/O operations.
+ They become visible at that interval in monitoring views such as
+ <link linkend="monitoring-pg-stat-io-view"> <structname>pg_stat_io</structname></link>
+ and <link linkend="monitoring-pg-stat-wal-view"> <structname>pg_stat_wal</structname></link>
+ during running transactions.
+ If this value is specified without units, it is taken as milliseconds.
+ The default is 10 seconds (<literal>10s</literal>), which is probably
+ about the smallest value you would want in practice for long running
+ transactions.
+ </para>
+ <note>
+ <para>
+ This parameter does not affect transactional statistics such as
+ <structname>pg_stat_all_tables</structname> columns (like
+ <structfield>n_tup_ins</structfield>, <structfield>n_tup_upd</structfield>,
+ <structfield>n_tup_del</structfield>), which are always flushed at transaction
+ boundaries to maintain consistency.
+ </para>
+ </note>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect2>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 9503aea5b4d..31523dea923 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1087,7 +1087,7 @@ XLogInsertRecord(XLogRecData *rdata,
/* Schedule next anytime stats update timeout */
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);
/* Required for the flush of pending stats WAL data */
pgstat_report_fixed = true;
@@ -2073,7 +2073,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, TimeLineID tli, bool opportunistic)
/* Schedule next anytime stats update timeout */
if (IsUnderPostmaster && !get_timeout_active(ANYTIME_STATS_UPDATE_TIMEOUT))
enable_timeout_after(ANYTIME_STATS_UPDATE_TIMEOUT,
- PGSTAT_MIN_INTERVAL);
+ pgstat_flush_interval);
/*
* Required for the flush of pending stats WAL data, per
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 2c9454677e9..dd174129403 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -203,6 +203,7 @@ 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;
/* ----------
@@ -1304,7 +1305,7 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
/* Schedule next anytime stats update timeout */
if (kind_info->flush_mode == FLUSH_ANYTIME && 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);
}
return entry_ref;
@@ -2172,6 +2173,19 @@ 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/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 9dcb24db975..f5b8c7b039c 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -69,7 +69,7 @@ pgstat_count_backend_io_op_time(IOObject io_object, IOContext io_context,
/* Schedule next anytime stats update timeout */
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);
backend_has_iostats = true;
pgstat_report_fixed = true;
@@ -89,7 +89,7 @@ pgstat_count_backend_io_op(IOObject io_object, IOContext io_context,
/* Schedule next anytime stats update timeout */
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);
backend_has_iostats = true;
pgstat_report_fixed = true;
diff --git a/src/backend/utils/activity/pgstat_io.c b/src/backend/utils/activity/pgstat_io.c
index 53dbf2a514b..b69a1e26f7d 100644
--- a/src/backend/utils/activity/pgstat_io.c
+++ b/src/backend/utils/activity/pgstat_io.c
@@ -82,7 +82,7 @@ pgstat_count_io_op(IOObject io_object, IOContext io_context, IOOp io_op,
/* Schedule next anytime stats update timeout */
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);
have_iostats = true;
pgstat_report_fixed = true;
diff --git a/src/backend/utils/activity/pgstat_slru.c b/src/backend/utils/activity/pgstat_slru.c
index 1d16cde1889..36231ee874b 100644
--- a/src/backend/utils/activity/pgstat_slru.c
+++ b/src/backend/utils/activity/pgstat_slru.c
@@ -226,7 +226,7 @@ get_slru_entry(int slru_idx)
/* Schedule next anytime stats update timeout */
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);
have_slrustats = true;
pgstat_report_fixed = true;
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index f0260e6e412..3bb43362e51 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2782,6 +2782,16 @@
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 c4f92fcdac8..6ce5a250170 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -669,6 +669,7 @@
#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 1651f16f966..e0f222695bf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -816,6 +816,7 @@ 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
--WLtTrIUEfQDmERxy
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Content-Disposition: attachment;
filename="v5-0003-Remove-useless-calls-to-flush-some-stats.patch"
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