From bddc98bb813e2a0453112b47431d324657eabaab Mon Sep 17 00:00:00 2001
From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Date: Mon, 5 Jan 2026 09:41:39 +0000
Subject: [PATCH v5 1/4] Add pgstat_report_anytime_stat() for periodic stats
 flushing

Long running transactions can accumulate significant statistics (WAL, IO, ...)
that remain unflushed until the transaction ends. This delays visibility of
resource usage in monitoring views like pg_stat_io and pg_stat_wal.

This commit introduces pgstat_report_anytime_stat(), which flushes
non transactional statistics even inside active transactions. A new timeout
handler fires every second (if enabled while adding pending stats) to call this
function, ensuring timely stats visibility without waiting for transaction completion.

Implementation details:

- Add PgStat_FlushMode enum to classify stats kinds:
  * FLUSH_ANYTIME: Stats that can always be flushed (WAL, IO, ...)
  * FLUSH_AT_TXN_BOUNDARY: Stats requiring transaction boundaries

- Modify pgstat_flush_pending_entries() and pgstat_flush_fixed_stats()
  to accept a boolean anytime_only parameter:
  * When false: flushes all stats (existing behavior)
  * When true: flushes only FLUSH_ANYTIME stats and skips FLUSH_AT_TXN_BOUNDARY stats

- This relies on the existing PGSTAT_MIN_INTERVAL to fire every 1 second, calling
pgstat_report_anytime_stat(false)

The force parameter in pgstat_report_anytime_stat() is currently unused (always
called with force=false) but reserved for future use cases requiring immediate
flushing.
---
 src/backend/access/transam/xlog.c           |   9 ++
 src/backend/postmaster/bgwriter.c           |   9 +-
 src/backend/postmaster/checkpointer.c       |  10 +-
 src/backend/postmaster/startup.c            |   2 +
 src/backend/postmaster/walsummarizer.c      |   9 +-
 src/backend/postmaster/walwriter.c          |   9 +-
 src/backend/replication/walreceiver.c       |   9 +-
 src/backend/tcop/postgres.c                 |  12 ++
 src/backend/utils/activity/pgstat.c         | 118 ++++++++++++++++----
 src/backend/utils/activity/pgstat_backend.c |   9 ++
 src/backend/utils/activity/pgstat_io.c      |   5 +
 src/backend/utils/activity/pgstat_slru.c    |   5 +
 src/backend/utils/init/globals.c            |   1 +
 src/backend/utils/init/postinit.c           |   3 +
 src/include/miscadmin.h                     |   1 +
 src/include/pgstat.h                        |   4 +
 src/include/utils/pgstat_internal.h         |  21 ++++
 src/include/utils/timeout.h                 |   1 +
 src/tools/pgindent/typedefs.list            |   1 +
 19 files changed, 213 insertions(+), 25 deletions(-)
   5.5% src/backend/access/transam/
  15.3% src/backend/postmaster/
   3.4% src/backend/replication/
   3.8% src/backend/tcop/
  57.0% src/backend/utils/activity/
   9.2% src/include/utils/
   5.3% src/

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 13ec6225b85..9503aea5b4d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1085,6 +1085,10 @@ XLogInsertRecord(XLogRecData *rdata,
 		pgWalUsage.wal_fpi += num_fpi;
 		pgWalUsage.wal_fpi_bytes += fpi_bytes;
 
+		/* 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);
+
 		/* Required for the flush of pending stats WAL data */
 		pgstat_report_fixed = true;
 	}
@@ -2066,6 +2070,11 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, TimeLineID tli, bool opportunistic)
 					pgWalUsage.wal_buffers_full++;
 					TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE();
 
+					/* 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);
+
 					/*
 					 * Required for the flush of pending stats WAL data, per
 					 * update of pgWalUsage.
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index 80e3088fc7e..ab5d0645026 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -49,7 +49,9 @@
 #include "storage/smgr.h"
 #include "storage/standby.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
 #include "utils/resowner.h"
+#include "utils/timeout.h"
 #include "utils/timestamp.h"
 
 /*
@@ -104,7 +106,7 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGINT, SIG_IGN);
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
+	InitializeTimeouts();		/* establishes SIGALRM handler */
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SIG_IGN);
@@ -114,6 +116,11 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len)
 	 */
 	pqsignal(SIGCHLD, SIG_DFL);
 
+	/*
+	 * Register timeouts needed
+	 */
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
+
 	/*
 	 * We just started, assume there has been either a shutdown or
 	 * end-of-recovery snapshot.
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 6482c21b8f9..6e187315613 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -66,8 +66,9 @@
 #include "utils/acl.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
 #include "utils/resowner.h"
-
+#include "utils/timeout.h"
 
 /*----------
  * Shared memory area for communication between checkpointer and backends
@@ -216,7 +217,7 @@ CheckpointerMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGINT, ReqShutdownXLOG);
 	pqsignal(SIGTERM, SIG_IGN); /* ignore SIGTERM */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
+	InitializeTimeouts();		/* establishes SIGALRM handler */
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SignalHandlerForShutdownRequest);
@@ -226,6 +227,11 @@ CheckpointerMain(const void *startup_data, size_t startup_data_len)
 	 */
 	pqsignal(SIGCHLD, SIG_DFL);
 
+	/*
+	 * Register timeouts needed
+	 */
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
+
 	/*
 	 * Initialize so that first time-driven event happens at the correct time.
 	 */
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index a1a4f65f9a9..498d147f0da 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -32,6 +32,7 @@
 #include "storage/standby.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
 #include "utils/timeout.h"
 
 
@@ -246,6 +247,7 @@ StartupProcessMain(const void *startup_data, size_t startup_data_len)
 	RegisterTimeout(STANDBY_DEADLOCK_TIMEOUT, StandbyDeadLockHandler);
 	RegisterTimeout(STANDBY_TIMEOUT, StandbyTimeoutHandler);
 	RegisterTimeout(STANDBY_LOCK_TIMEOUT, StandbyLockTimeoutHandler);
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
 
 	/*
 	 * Unblock signals (they were blocked when the postmaster forked us)
diff --git a/src/backend/postmaster/walsummarizer.c b/src/backend/postmaster/walsummarizer.c
index c3d56c866d3..cec5dfdb430 100644
--- a/src/backend/postmaster/walsummarizer.c
+++ b/src/backend/postmaster/walsummarizer.c
@@ -48,6 +48,8 @@
 #include "storage/shmem.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
+#include "utils/timeout.h"
 #include "utils/wait_event.h"
 
 /*
@@ -250,7 +252,7 @@ WalSummarizerMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGINT, SignalHandlerForShutdownRequest);
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
+	InitializeTimeouts();		/* establishes SIGALRM handler */
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SIG_IGN); /* not used */
@@ -272,6 +274,11 @@ WalSummarizerMain(const void *startup_data, size_t startup_data_len)
 	 */
 	pqsignal(SIGCHLD, SIG_DFL);
 
+	/*
+	 * Register timeouts needed
+	 */
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
+
 	/*
 	 * If an exception is encountered, processing resumes here.
 	 */
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 38ec8a4c8c7..7416ca703c9 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -61,7 +61,9 @@
 #include "storage/smgr.h"
 #include "utils/hsearch.h"
 #include "utils/memutils.h"
+#include "utils/pgstat_internal.h"
 #include "utils/resowner.h"
+#include "utils/timeout.h"
 
 
 /*
@@ -107,7 +109,7 @@ WalWriterMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGINT, SignalHandlerForShutdownRequest);
 	pqsignal(SIGTERM, SignalHandlerForShutdownRequest);
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
+	InitializeTimeouts();		/* establishes SIGALRM handler */
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SIG_IGN); /* not used */
@@ -117,6 +119,11 @@ WalWriterMain(const void *startup_data, size_t startup_data_len)
 	 */
 	pqsignal(SIGCHLD, SIG_DFL);
 
+	/*
+	 * Register timeouts needed
+	 */
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
+
 	/*
 	 * Create a memory context that we will do all our work in.  We do this so
 	 * that we can reset the context during error recovery and thereby avoid
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 8b99160ed0e..24d7ef795cb 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -77,7 +77,9 @@
 #include "utils/builtins.h"
 #include "utils/guc.h"
 #include "utils/pg_lsn.h"
+#include "utils/pgstat_internal.h"
 #include "utils/ps_status.h"
+#include "utils/timeout.h"
 #include "utils/timestamp.h"
 
 
@@ -253,7 +255,7 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 	pqsignal(SIGINT, SIG_IGN);
 	pqsignal(SIGTERM, die);		/* request shutdown */
 	/* SIGQUIT handler was already set up by InitPostmasterChild */
-	pqsignal(SIGALRM, SIG_IGN);
+	InitializeTimeouts();		/* establishes SIGALRM handler */
 	pqsignal(SIGPIPE, SIG_IGN);
 	pqsignal(SIGUSR1, procsignal_sigusr1_handler);
 	pqsignal(SIGUSR2, SIG_IGN);
@@ -261,6 +263,11 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 	/* Reset some signals that are accepted by postmaster but not here */
 	pqsignal(SIGCHLD, SIG_DFL);
 
+	/*
+	 * Register timeouts needed
+	 */
+	RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT, AnytimeStatsUpdateTimeoutHandler);
+
 	/* Load the libpq-specific functions */
 	load_file("libpqwalreceiver", false);
 	if (WalReceiverFunctions == NULL)
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index b4a8d2f3a1c..d19aa45400d 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3530,6 +3530,18 @@ ProcessInterrupts(void)
 		pgstat_report_stat(true);
 	}
 
+	/*
+	 * Flush stats outside of transaction boundary if the timeout fired.
+	 * Unlike transactional stats, these can be flushed even inside a running
+	 * transaction.
+	 */
+	if (AnytimeStatsUpdateTimeoutPending)
+	{
+		AnytimeStatsUpdateTimeoutPending = false;
+
+		pgstat_report_anytime_stat(false);
+	}
+
 	if (ProcSignalBarrierPending)
 		ProcessProcSignalBarrier();
 
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 11bb71cad5a..2c9454677e9 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -112,6 +112,7 @@
 #include "utils/guc_hooks.h"
 #include "utils/memutils.h"
 #include "utils/pgstat_internal.h"
+#include "utils/timeout.h"
 #include "utils/timestamp.h"
 
 
@@ -122,8 +123,6 @@
  * ----------
  */
 
-/* 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 */
@@ -187,7 +186,8 @@ static void pgstat_init_snapshot_fixed(void);
 
 static void pgstat_reset_after_failure(void);
 
-static bool pgstat_flush_pending_entries(bool nowait);
+static bool pgstat_flush_pending_entries(bool nowait, bool anytime_only);
+static bool pgstat_flush_fixed_stats(bool nowait, bool anytime_only);
 
 static void pgstat_prep_snapshot(void);
 static void pgstat_build_snapshot(void);
@@ -288,6 +288,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = true,
+		.flush_mode = FLUSH_AT_TXN_BOUNDARY,
 		/* so pg_stat_database entries can be seen in all databases */
 		.accessed_across_databases = true,
 
@@ -305,6 +306,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = true,
+		.flush_mode = FLUSH_AT_TXN_BOUNDARY,
 
 		.shared_size = sizeof(PgStatShared_Relation),
 		.shared_data_off = offsetof(PgStatShared_Relation, stats),
@@ -321,6 +323,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = true,
+		.flush_mode = FLUSH_AT_TXN_BOUNDARY,
 
 		.shared_size = sizeof(PgStatShared_Function),
 		.shared_data_off = offsetof(PgStatShared_Function, stats),
@@ -336,6 +339,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = true,
+		.flush_mode = FLUSH_AT_TXN_BOUNDARY,
 
 		.accessed_across_databases = true,
 
@@ -353,6 +357,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = true,
+		.flush_mode = FLUSH_AT_TXN_BOUNDARY,
 		/* so pg_stat_subscription_stats entries can be seen in all databases */
 		.accessed_across_databases = true,
 
@@ -370,6 +375,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = false,
 		.write_to_file = false,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.accessed_across_databases = true,
 
@@ -388,6 +394,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, archiver),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, archiver),
@@ -404,6 +411,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, bgwriter),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, bgwriter),
@@ -420,6 +428,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, checkpointer),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, checkpointer),
@@ -436,6 +445,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, io),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, io),
@@ -453,6 +463,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, slru),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, slru),
@@ -470,6 +481,7 @@ static const PgStat_KindInfo pgstat_kind_builtin_infos[PGSTAT_KIND_BUILTIN_SIZE]
 
 		.fixed_amount = true,
 		.write_to_file = true,
+		.flush_mode = FLUSH_ANYTIME,
 
 		.snapshot_ctl_off = offsetof(PgStat_Snapshot, wal),
 		.shared_ctl_off = offsetof(PgStat_ShmemControl, wal),
@@ -775,23 +787,11 @@ pgstat_report_stat(bool force)
 	partial_flush = false;
 
 	/* flush of variable-numbered stats tracked in pending entries list */
-	partial_flush |= pgstat_flush_pending_entries(nowait);
+	partial_flush |= pgstat_flush_pending_entries(nowait, false);
 
 	/* flush of other stats kinds */
 	if (pgstat_report_fixed)
-	{
-		for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
-		{
-			const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
-
-			if (!kind_info)
-				continue;
-			if (!kind_info->flush_static_cb)
-				continue;
-
-			partial_flush |= kind_info->flush_static_cb(nowait);
-		}
-	}
+		partial_flush |= pgstat_flush_fixed_stats(nowait, false);
 
 	last_flush = now;
 
@@ -1293,12 +1293,18 @@ pgstat_prep_pending_entry(PgStat_Kind kind, Oid dboid, uint64 objid, bool *creat
 
 	if (entry_ref->pending == NULL)
 	{
-		size_t		entrysize = pgstat_get_kind_info(kind)->pending_size;
+		const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+		size_t		entrysize = kind_info->pending_size;
 
 		Assert(entrysize != (size_t) -1);
 
 		entry_ref->pending = MemoryContextAllocZero(pgStatPendingContext, entrysize);
 		dlist_push_tail(&pgStatPending, &entry_ref->pending_node);
+
+		/* 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);
 	}
 
 	return entry_ref;
@@ -1345,9 +1351,14 @@ pgstat_delete_pending_entry(PgStat_EntryRef *entry_ref)
 
 /*
  * Flush out pending variable-numbered stats.
+ *
+ * If anytime_only is true, only flushes FLUSH_ANYTIME entries.
+ * This is safe to call inside transactions.
+ *
+ * If anytime_only is false, flushes all entries.
  */
 static bool
-pgstat_flush_pending_entries(bool nowait)
+pgstat_flush_pending_entries(bool nowait, bool anytime_only)
 {
 	bool		have_pending = false;
 	dlist_node *cur = NULL;
@@ -1377,6 +1388,20 @@ pgstat_flush_pending_entries(bool nowait)
 		Assert(!kind_info->fixed_amount);
 		Assert(kind_info->flush_pending_cb != NULL);
 
+		/* Skip transactional stats if we're in anytime_only mode */
+		if (anytime_only && kind_info->flush_mode == FLUSH_AT_TXN_BOUNDARY)
+		{
+			have_pending = true;
+
+			if (dlist_has_next(&pgStatPending, cur))
+				next = dlist_next_node(&pgStatPending, cur);
+			else
+				next = NULL;
+
+			cur = next;
+			continue;
+		}
+
 		/* flush the stats, if possible */
 		did_flush = kind_info->flush_pending_cb(entry_ref, nowait);
 
@@ -1402,6 +1427,33 @@ pgstat_flush_pending_entries(bool nowait)
 	return have_pending;
 }
 
+/*
+ * Flush fixed-amount stats.
+ *
+ * If anytime_only is true, only flushes FLUSH_ANYTIME stats (safe inside transactions).
+ * If anytime_only is false, flushes all stats with flush_static_cb.
+ */
+static bool
+pgstat_flush_fixed_stats(bool nowait, bool anytime_only)
+{
+	bool		partial_flush = false;
+
+	for (PgStat_Kind kind = PGSTAT_KIND_MIN; kind <= PGSTAT_KIND_MAX; kind++)
+	{
+		const PgStat_KindInfo *kind_info = pgstat_get_kind_info(kind);
+
+		if (!kind_info || !kind_info->flush_static_cb)
+			continue;
+
+		/* Skip transactional stats if we're in anytime_only mode */
+		if (anytime_only && kind_info->flush_mode == FLUSH_AT_TXN_BOUNDARY)
+			continue;
+
+		partial_flush |= kind_info->flush_static_cb(nowait);
+	}
+
+	return partial_flush;
+}
 
 /* ------------------------------------------------------------
  * Helper / infrastructure functions
@@ -2119,3 +2171,31 @@ assign_stats_fetch_consistency(int newval, void *extra)
 	if (pgstat_fetch_consistency != newval)
 		force_stats_snapshot_clear = true;
 }
+
+/*
+ * Flushes only FLUSH_ANYTIME stats using non-blocking locks. Transactional
+ * stats (FLUSH_AT_TXN_BOUNDARY) remain pending until transaction boundary.
+ * Safe to call inside transactions.
+ */
+void
+pgstat_report_anytime_stat(bool force)
+{
+	bool		nowait = !force;
+
+	pgstat_assert_is_up();
+
+	/* Flush stats outside of transaction boundary */
+	pgstat_flush_pending_entries(nowait, true);
+	pgstat_flush_fixed_stats(nowait, true);
+}
+
+/*
+ * Timeout handler for flushing non-transactional stats.
+ */
+void
+AnytimeStatsUpdateTimeoutHandler(void)
+{
+	AnytimeStatsUpdateTimeoutPending = true;
+	InterruptPending = true;
+	SetLatch(MyLatch);
+}
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 1350f5f62f1..9dcb24db975 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -31,6 +31,7 @@
 #include "storage/procarray.h"
 #include "utils/memutils.h"
 #include "utils/pgstat_internal.h"
+#include "utils/timeout.h"
 
 /*
  * Backend statistics counts waiting to be flushed out. These counters may be
@@ -66,6 +67,10 @@ pgstat_count_backend_io_op_time(IOObject io_object, IOContext io_context,
 	INSTR_TIME_ADD(PendingBackendStats.pending_io.pending_times[io_object][io_context][io_op],
 				   io_time);
 
+	/* 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);
+
 	backend_has_iostats = true;
 	pgstat_report_fixed = true;
 }
@@ -82,6 +87,10 @@ pgstat_count_backend_io_op(IOObject io_object, IOContext io_context,
 	PendingBackendStats.pending_io.counts[io_object][io_context][io_op] += cnt;
 	PendingBackendStats.pending_io.bytes[io_object][io_context][io_op] += bytes;
 
+	/* 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);
+
 	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 28de24538dc..53dbf2a514b 100644
--- a/src/backend/utils/activity/pgstat_io.c
+++ b/src/backend/utils/activity/pgstat_io.c
@@ -19,6 +19,7 @@
 #include "executor/instrument.h"
 #include "storage/bufmgr.h"
 #include "utils/pgstat_internal.h"
+#include "utils/timeout.h"
 
 static PgStat_PendingIO PendingIOStats;
 static bool have_iostats = false;
@@ -79,6 +80,10 @@ pgstat_count_io_op(IOObject io_object, IOContext io_context, IOOp io_op,
 	/* Add the per-backend counts */
 	pgstat_count_backend_io_op(io_object, io_context, io_op, cnt, bytes);
 
+	/* 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);
+
 	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 2190f388eae..1d16cde1889 100644
--- a/src/backend/utils/activity/pgstat_slru.c
+++ b/src/backend/utils/activity/pgstat_slru.c
@@ -19,6 +19,7 @@
 
 #include "utils/pgstat_internal.h"
 #include "utils/timestamp.h"
+#include "utils/timeout.h"
 
 
 static inline PgStat_SLRUStats *get_slru_entry(int slru_idx);
@@ -223,6 +224,10 @@ get_slru_entry(int slru_idx)
 
 	Assert((slru_idx >= 0) && (slru_idx < SLRU_NUM_ELEMENTS));
 
+	/* 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);
+
 	have_slrustats = true;
 	pgstat_report_fixed = true;
 
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index 36ad708b360..ad44826c39e 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -40,6 +40,7 @@ volatile sig_atomic_t IdleSessionTimeoutPending = false;
 volatile sig_atomic_t ProcSignalBarrierPending = false;
 volatile sig_atomic_t LogMemoryContextPending = false;
 volatile sig_atomic_t IdleStatsUpdateTimeoutPending = false;
+volatile sig_atomic_t AnytimeStatsUpdateTimeoutPending = false;
 volatile uint32 InterruptHoldoffCount = 0;
 volatile uint32 QueryCancelHoldoffCount = 0;
 volatile uint32 CritSectionCount = 0;
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 3f401faf3de..f45365f47f7 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -64,6 +64,7 @@
 #include "utils/injection_point.h"
 #include "utils/memutils.h"
 #include "utils/pg_locale.h"
+#include "utils/pgstat_internal.h"
 #include "utils/portal.h"
 #include "utils/ps_status.h"
 #include "utils/snapmgr.h"
@@ -765,6 +766,8 @@ InitPostgres(const char *in_dbname, Oid dboid,
 		RegisterTimeout(CLIENT_CONNECTION_CHECK_TIMEOUT, ClientCheckTimeoutHandler);
 		RegisterTimeout(IDLE_STATS_UPDATE_TIMEOUT,
 						IdleStatsUpdateTimeoutHandler);
+		RegisterTimeout(ANYTIME_STATS_UPDATE_TIMEOUT,
+						AnytimeStatsUpdateTimeoutHandler);
 	}
 
 	/*
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index db559b39c4d..8aeb9628871 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -96,6 +96,7 @@ extern PGDLLIMPORT volatile sig_atomic_t IdleSessionTimeoutPending;
 extern PGDLLIMPORT volatile sig_atomic_t ProcSignalBarrierPending;
 extern PGDLLIMPORT volatile sig_atomic_t LogMemoryContextPending;
 extern PGDLLIMPORT volatile sig_atomic_t IdleStatsUpdateTimeoutPending;
+extern PGDLLIMPORT volatile sig_atomic_t AnytimeStatsUpdateTimeoutPending;
 
 extern PGDLLIMPORT volatile sig_atomic_t CheckClientConnectionPending;
 extern PGDLLIMPORT volatile sig_atomic_t ClientConnectionLost;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index fff7ecc2533..1651f16f966 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -35,6 +35,9 @@
 /* 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
 {
@@ -533,6 +536,7 @@ extern void pgstat_initialize(void);
 
 /* Functions called from backends */
 extern long pgstat_report_stat(bool force);
+extern void pgstat_report_anytime_stat(bool force);
 extern void pgstat_force_next_flush(void);
 
 extern void pgstat_reset_counters(void);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 9b8fbae00ed..a9190078d0e 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -224,6 +224,19 @@ typedef struct PgStat_SubXactStatus
 	PgStat_TableXactStatus *first;	/* head of list for this subxact */
 } PgStat_SubXactStatus;
 
+/*
+ * Flush mode for statistics kinds.
+ *
+ * FLUSH_AT_TXN_BOUNDARY has to be the first because we want it to be the
+ * default value.
+ */
+typedef enum PgStat_FlushMode
+{
+	FLUSH_AT_TXN_BOUNDARY,		/* All fields can only be flushed at
+								 * transaction boundary */
+	FLUSH_ANYTIME,				/* All fields can be flushed anytime,
+								 * including within transactions */
+} PgStat_FlushMode;
 
 /*
  * Metadata for a specific kind of statistics.
@@ -251,6 +264,13 @@ typedef struct PgStat_KindInfo
 	 */
 	bool		track_entry_count:1;
 
+	/*
+	 * Some stats have to be updated only at transaction boundaries (such as
+	 * tuples_inserted updated, deleted), so it's very important to set the
+	 * right flush mode (FLUSH_AT_TXN_BOUNDARY being the default).
+	 */
+	PgStat_FlushMode flush_mode;
+
 	/*
 	 * The size of an entry in the shared stats hash table (pointed to by
 	 * PgStatShared_HashEntry->body).  For fixed-numbered statistics, this is
@@ -677,6 +697,7 @@ extern PgStat_EntryRef *pgstat_fetch_pending_entry(PgStat_Kind kind,
 
 extern void *pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, uint64 objid);
 extern void pgstat_snapshot_fixed(PgStat_Kind kind);
+extern void AnytimeStatsUpdateTimeoutHandler(void);
 
 
 /*
diff --git a/src/include/utils/timeout.h b/src/include/utils/timeout.h
index 0965b590b34..10723bb664c 100644
--- a/src/include/utils/timeout.h
+++ b/src/include/utils/timeout.h
@@ -35,6 +35,7 @@ typedef enum TimeoutId
 	IDLE_SESSION_TIMEOUT,
 	IDLE_STATS_UPDATE_TIMEOUT,
 	CLIENT_CONNECTION_CHECK_TIMEOUT,
+	ANYTIME_STATS_UPDATE_TIMEOUT,
 	STARTUP_PROGRESS_TIMEOUT,
 	/* First user-definable timeout reason */
 	USER_TIMEOUT,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 9f5ee8fd482..860f835c088 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2268,6 +2268,7 @@ PgStat_Counter
 PgStat_EntryRef
 PgStat_EntryRefHashEntry
 PgStat_FetchConsistency
+PgStat_FlushMode
 PgStat_FunctionCallUsage
 PgStat_FunctionCounts
 PgStat_HashKey
-- 
2.34.1

