Subject: [PATCH v7 1/5] Add pgstat_report_anytime_stat() for periodic stats flushing

From: Bertrand Drouvot <[email-masked]>
Date: Mon, 5 Jan 2026 09:41:39 +0000

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 and produces
spikes when flushed.

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

- The flush_pending_cb and flush_static_cb callbacks now receive an anytime_only
boolean parameter. Most of the time it's not used (except for assertions), but it's
preparatory work for moving the relations stats to anytime (without introducin
a new callback).

- Add pgstat_schedule_anytime_update() macro to schedule the next anytime flush,
relying on PGSTAT_MIN_INTERVAL

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             |   6 +
 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/replication/walsender.c           |   8 +-
 src/backend/tcop/postgres.c                   |  12 ++
 src/backend/utils/activity/pgstat.c           | 112 ++++++++++++++----
 src/backend/utils/activity/pgstat_backend.c   |  13 +-
 src/backend/utils/activity/pgstat_bgwriter.c  |   2 +-
 .../utils/activity/pgstat_checkpointer.c      |   2 +-
 src/backend/utils/activity/pgstat_database.c  |   2 +-
 src/backend/utils/activity/pgstat_function.c  |   4 +-
 src/backend/utils/activity/pgstat_io.c        |  10 +-
 src/backend/utils/activity/pgstat_relation.c  |  12 +-
 src/backend/utils/activity/pgstat_slru.c      |   6 +-
 .../utils/activity/pgstat_subscription.c      |   4 +-
 src/backend/utils/activity/pgstat_wal.c       |  10 +-
 src/backend/utils/init/globals.c              |   1 +
 src/backend/utils/init/postinit.c             |   3 +
 src/include/miscadmin.h                       |   1 +
 src/include/pgstat.h                          |  16 +++
 src/include/utils/pgstat_internal.h           |  52 ++++++--
 src/include/utils/timeout.h                   |   1 +
 .../test_custom_stats/test_custom_var_stats.c |   4 +-
 src/tools/pgindent/typedefs.list              |   1 +
 28 files changed, 264 insertions(+), 66 deletions(-)
  10.8% src/backend/postmaster/
   6.0% src/backend/replication/
  50.7% src/backend/utils/activity/
   6.0% src/backend/
  19.3% src/include/utils/
   5.6% src/include/

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 13ec6225b85..d01b11c7470 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -1085,6 +1085,9 @@ XLogInsertRecord(XLogRecData *rdata,
 		pgWalUsage.wal_fpi += num_fpi;
 		pgWalUsage.wal_fpi_bytes += fpi_bytes;
 
+		/* Schedule next anytime stats update timeout */
+		pgstat_schedule_anytime_update();
+
 		/* Required for the flush of pending stats WAL data */
 		pgstat_report_fixed = true;
 	}
@@ -2066,6 +2069,9 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, TimeLineID tli, bool opportunistic)
 					pgWalUsage.wal_buffers_full++;
 					TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE();
 
+					/* Schedule next anytime stats update timeout */
+					pgstat_schedule_anytime_update();
+
 					/*
 					 * 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 0956bd39a85..059c601c3b8 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"
 
 /*
@@ -103,7 +105,7 @@ 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);
@@ -113,6 +115,11 @@ 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 e03c19123bc..e11c4b099c8 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
@@ -215,7 +216,7 @@ 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);
@@ -225,6 +226,11 @@ 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 cdbe53dd262..4954fe425b7 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"

@@ -245,6 +246,7 @@ 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 2d8f57099fd..9f8ef8159d1 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"
 
 /*
@@ -249,7 +251,7 @@ 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 */
@@ -271,6 +273,11 @@ 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 23e79a32345..ded0f250288 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"

 /*
@@ -106,7 +108,7 @@ 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 */
@@ -116,6 +118,11 @@ 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 10e64a7d1f4..11b7c114d3b 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"

@@ -252,7 +254,7 @@ 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);
@@ -260,6 +262,11 @@ 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/replication/walsender.c b/src/backend/replication/walsender.c
index 2cde8ebc729..a7214d0dc6f 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1987,8 +1987,8 @@ WalSndWaitForWal(XLogRecPtr loc)
 		if (TimestampDifferenceExceeds(last_flush, now,
 									   WALSENDER_STATS_FLUSH_INTERVAL))
 		{
-			pgstat_flush_io(false);
-			(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
+			pgstat_flush_io(false, true);
+			(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO, true);
 			last_flush = now;
 		}
 
@@ -3016,8 +3016,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 			if (TimestampDifferenceExceeds(last_flush, now,
 										   WALSENDER_STATS_FLUSH_INTERVAL))
 			{
-				pgstat_flush_io(false);
-				(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
+				pgstat_flush_io(false, true);
+				(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO, true);
 				last_flush = now;
 			}
 
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 21de158adbb..2089de782d5 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3564,6 +3564,18 @@ 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..a4ff64dc5ce 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,
 
@@ -436,6 +442,7 @@ 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 +460,7 @@ 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 +478,7 @@ 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 +784,11 @@ 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;
 
@@ -1293,7 +1290,8 @@ 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);
 
@@ -1345,9 +1343,14 @@ 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;
@@ -1377,8 +1380,22 @@ 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);
+		did_flush = kind_info->flush_pending_cb(entry_ref, nowait, anytime_only);
 
 		Assert(did_flush || nowait);
 
@@ -1402,6 +1419,33 @@ 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, anytime_only);
+	}
+
+	return partial_flush;
+}
 
 /* ------------------------------------------------------------
  * Helper / infrastructure functions
@@ -2119,3 +2163,31 @@ 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 anytime 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 f2f8d3ff75f..b09316d3ab3 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 +67,9 @@ 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 */
+	pgstat_schedule_anytime_update();
+
 	backend_has_iostats = true;
 	pgstat_report_fixed = true;
 }
@@ -82,6 +86,9 @@ 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 */
+	pgstat_schedule_anytime_update();
+
 	backend_has_iostats = true;
 	pgstat_report_fixed = true;
 }
@@ -268,7 +275,7 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
  * if some statistics could not be flushed due to lock contention.
  */
 bool
-pgstat_flush_backend(bool nowait, bits32 flags)
+pgstat_flush_backend(bool nowait, bits32 flags, bool anytime_only)
 {
 	PgStat_EntryRef *entry_ref;
 	bool		has_pending_data = false;
@@ -311,9 +318,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
  * If some stats could not be flushed due to lock contention, return true.
  */
 bool
-pgstat_backend_flush_cb(bool nowait)
+pgstat_backend_flush_cb(bool nowait, bool anytime_only)
 {
-	return pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_ALL);
+	return pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_ALL, anytime_only);
 }
 
 /*
diff --git a/src/backend/utils/activity/pgstat_bgwriter.c b/src/backend/utils/activity/pgstat_bgwriter.c
index ed2fd801189..1c5f0c3ec40 100644
--- a/src/backend/utils/activity/pgstat_bgwriter.c
+++ b/src/backend/utils/activity/pgstat_bgwriter.c
@@ -61,7 +61,7 @@ pgstat_report_bgwriter(void)
 	/*
 	 * Report IO statistics
 	 */
-	pgstat_flush_io(false);
+	pgstat_flush_io(false, true);
 }
 
 /*
diff --git a/src/backend/utils/activity/pgstat_checkpointer.c b/src/backend/utils/activity/pgstat_checkpointer.c
index 1f70194b7a7..2d89a082464 100644
--- a/src/backend/utils/activity/pgstat_checkpointer.c
+++ b/src/backend/utils/activity/pgstat_checkpointer.c
@@ -68,7 +68,7 @@ pgstat_report_checkpointer(void)
 	/*
 	 * Report IO statistics
 	 */
-	pgstat_flush_io(false);
+	pgstat_flush_io(false, true);
 }
 
 /*
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..8e86df60461 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -435,7 +435,7 @@ pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts)
  * false without flushing the entry.  Otherwise returns true.
  */
 bool
-pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
+pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only)
 {
 	PgStatShared_Database *sharedent;
 	PgStat_StatDBEntry *pendingent;
diff --git a/src/backend/utils/activity/pgstat_function.c b/src/backend/utils/activity/pgstat_function.c
index e6b84283c6c..5ba4958382f 100644
--- a/src/backend/utils/activity/pgstat_function.c
+++ b/src/backend/utils/activity/pgstat_function.c
@@ -190,11 +190,13 @@ pgstat_end_function_usage(PgStat_FunctionCallUsage *fcu, bool finalize)
  * false without flushing the entry.  Otherwise returns true.
  */
 bool
-pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
+pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only)
 {
 	PgStat_FunctionCounts *localent;
 	PgStatShared_Function *shfuncent;
 
+	Assert(!anytime_only);
+
 	localent = (PgStat_FunctionCounts *) entry_ref->pending;
 	shfuncent = (PgStatShared_Function *) entry_ref->shared_stats;
 
diff --git a/src/backend/utils/activity/pgstat_io.c b/src/backend/utils/activity/pgstat_io.c
index 28de24538dc..7cd32900236 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 +80,9 @@ 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 */
+	pgstat_schedule_anytime_update();
+
 	have_iostats = true;
 	pgstat_report_fixed = true;
 }
@@ -172,9 +176,9 @@ pgstat_fetch_stat_io(void)
  * Simpler wrapper of pgstat_io_flush_cb()
  */
 void
-pgstat_flush_io(bool nowait)
+pgstat_flush_io(bool nowait, bool anytime_only)
 {
-	(void) pgstat_io_flush_cb(nowait);
+	(void) pgstat_io_flush_cb(nowait, anytime_only);
 }
 
 /*
@@ -186,7 +190,7 @@ pgstat_flush_io(bool nowait)
  * acquired. Otherwise, return false.
  */
 bool
-pgstat_io_flush_cb(bool nowait)
+pgstat_io_flush_cb(bool nowait, bool anytime_only)
 {
 	LWLock	   *bktype_lock;
 	PgStat_BktypeIO *bktype_shstats;
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index bc8c43b96aa..04d21483d93 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -267,8 +267,8 @@ pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples,
 	 * is done -- which will likely vacuum many relations -- or until the
 	 * VACUUM command has processed all tables and committed.
 	 */
-	pgstat_flush_io(false);
-	(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
+	pgstat_flush_io(false, true);
+	(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO, true);
 }
 
 /*
@@ -362,8 +362,8 @@ pgstat_report_analyze(Relation rel,
 	pgstat_unlock_entry(entry_ref);
 
 	/* see pgstat_report_vacuum() */
-	pgstat_flush_io(false);
-	(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
+	pgstat_flush_io(false, true);
+	(void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO, true);
 }
 
 /*
@@ -812,7 +812,7 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
  * entry when successfully flushing.
  */
 bool
-pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
+pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only)
 {
 	Oid			dboid;
 	PgStat_TableStatus *lstats; /* pending stats entry  */
@@ -820,6 +820,8 @@ pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
 	PgStat_StatTabEntry *tabentry;	/* table entry of shared stats */
 	PgStat_StatDBEntry *dbentry;	/* pending database entry */
 
+	Assert(!anytime_only);
+
 	dboid = entry_ref->shared_entry->key.dboid;
 	lstats = (PgStat_TableStatus *) entry_ref->pending;
 	shtabstats = (PgStatShared_Relation *) entry_ref->shared_stats;
diff --git a/src/backend/utils/activity/pgstat_slru.c b/src/backend/utils/activity/pgstat_slru.c
index 2190f388eae..bf8a4d58673 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);
@@ -139,7 +140,7 @@ pgstat_get_slru_index(const char *name)
  * acquired. Otherwise return false.
  */
 bool
-pgstat_slru_flush_cb(bool nowait)
+pgstat_slru_flush_cb(bool nowait, bool anytime_only)
 {
 	PgStatShared_SLRU *stats_shmem = &pgStatLocal.shmem->slru;
 	int			i;
@@ -223,6 +224,9 @@ get_slru_entry(int slru_idx)
 
 	Assert((slru_idx >= 0) && (slru_idx < SLRU_NUM_ELEMENTS));
 
+	/* Schedule next anytime stats update timeout */
+	pgstat_schedule_anytime_update();
+
 	have_slrustats = true;
 	pgstat_report_fixed = true;
 
diff --git a/src/backend/utils/activity/pgstat_subscription.c b/src/backend/utils/activity/pgstat_subscription.c
index 500b1899188..c4614817966 100644
--- a/src/backend/utils/activity/pgstat_subscription.c
+++ b/src/backend/utils/activity/pgstat_subscription.c
@@ -116,11 +116,13 @@ pgstat_fetch_stat_subscription(Oid subid)
  * false without flushing the entry.  Otherwise returns true.
  */
 bool
-pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait)
+pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only)
 {
 	PgStat_BackendSubEntry *localent;
 	PgStatShared_Subscription *shsubent;
 
+	Assert(!anytime_only);
+
 	localent = (PgStat_BackendSubEntry *) entry_ref->pending;
 	shsubent = (PgStatShared_Subscription *) entry_ref->shared_stats;
 
diff --git a/src/backend/utils/activity/pgstat_wal.c b/src/backend/utils/activity/pgstat_wal.c
index 183e0a7a97b..2c2f3f10e10 100644
--- a/src/backend/utils/activity/pgstat_wal.c
+++ b/src/backend/utils/activity/pgstat_wal.c
@@ -51,12 +51,12 @@ pgstat_report_wal(bool force)
 	nowait = !force;
 
 	/* flush wal stats */
-	(void) pgstat_wal_flush_cb(nowait);
-	pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_WAL);
+	(void) pgstat_wal_flush_cb(nowait, true);
+	(void) pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_WAL, true);
 
 	/* flush IO stats */
-	pgstat_flush_io(nowait);
-	(void) pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_IO);
+	pgstat_flush_io(nowait, true);
+	(void) pgstat_flush_backend(nowait, PGSTAT_BACKEND_FLUSH_IO, true);
 }
 
 /*
@@ -88,7 +88,7 @@ pgstat_wal_have_pending(void)
  * acquired. Otherwise return false.
  */
 bool
-pgstat_wal_flush_cb(bool nowait)
+pgstat_wal_flush_cb(bool nowait, bool anytime_only)
 {
 	PgStatShared_Wal *stats_shmem = &pgStatLocal.shmem->wal;
 	WalUsage	wal_usage_diff = {0};
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 b59e08605cc..eeeac1bf39a 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"
@@ -773,6 +774,8 @@ 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 f16f35659b9..84e698da214 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..b340a680614 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
 {
@@ -533,8 +536,21 @@ 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);
 
+/*
+ * Schedule the next anytime stats update timeout.
+ *
+ * This should be called whenever accumulating statistics that support
+ * FLUSH_ANYTIME flushing mode.
+ */
+#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);	\
+	} while (0)
+
 extern void pgstat_reset_counters(void);
 extern void pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid);
 extern void pgstat_reset_of_kind(PgStat_Kind kind);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 9b8fbae00ed..607f4255268 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 +264,16 @@ typedef struct PgStat_KindInfo
 	 */
 	bool		track_entry_count:1;
 
+	/*
+	 * The mode of when to flush stats. See PgStat_FlushMode for more details.
+	 *
+	 * This member only has meaning for statistics kinds that accumulate
+	 * pending stats and use flush callbacks. For kinds that write directly to
+	 * shared memory (e.g., archiver, bgwriter, checkpointer), this member has
+	 * no effect.
+	 */
+	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
@@ -297,8 +320,10 @@ typedef struct PgStat_KindInfo
 	 * For variable-numbered stats: flush pending stats. Required if pending
 	 * data is used. See flush_static_cb when dealing with stats data that
 	 * that cannot use PgStat_EntryRef->pending.
+	 *
+	 * The anytime_only parameter indicates whether this is an anytime flush.
 	 */
-	bool		(*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait);
+	bool		(*flush_pending_cb) (PgStat_EntryRef *sr, bool nowait, bool anytime_only);
 
 	/*
 	 * For variable-numbered stats: delete pending stats. Optional.
@@ -366,8 +391,10 @@ typedef struct PgStat_KindInfo
 	 *
 	 * "pgstat_report_fixed" needs to be set to trigger the flush of pending
 	 * stats.
+	 *
+	 * The anytime_only parameter indicates whether this is an anytime flush.
 	 */
-	bool		(*flush_static_cb) (bool nowait);
+	bool		(*flush_static_cb) (bool nowait, bool anytime_only);
 
 	/*
 	 * For fixed-numbered statistics: Reset All.
@@ -677,6 +704,7 @@ 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);

 /*
@@ -696,8 +724,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
 #define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
 
-extern bool pgstat_flush_backend(bool nowait, bits32 flags);
-extern bool pgstat_backend_flush_cb(bool nowait);
+extern bool pgstat_flush_backend(bool nowait, bits32 flags, bool anytime_only);
+extern bool pgstat_backend_flush_cb(bool nowait, bool anytime_only);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
 
@@ -729,7 +757,7 @@ extern void AtEOXact_PgStat_Database(bool isCommit, bool parallel);
 
 extern PgStat_StatDBEntry *pgstat_prep_database_pending(Oid dboid);
 extern void pgstat_reset_database_timestamp(Oid dboid, TimestampTz ts);
-extern bool pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
+extern bool pgstat_database_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only);
 extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);

@@ -737,7 +765,7 @@ extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, Time
  * Functions in pgstat_function.c
  */
 
-extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
+extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only);
 extern void pgstat_function_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);

@@ -745,9 +773,9 @@ extern void pgstat_function_reset_timestamp_cb(PgStatShared_Common *header, Time
  * Functions in pgstat_io.c
  */
 
-extern void pgstat_flush_io(bool nowait);
+extern void pgstat_flush_io(bool nowait, bool anytime_only);
 
-extern bool pgstat_io_flush_cb(bool nowait);
+extern bool pgstat_io_flush_cb(bool nowait, bool anytime_only);
 extern void pgstat_io_init_shmem_cb(void *stats);
 extern void pgstat_io_reset_all_cb(TimestampTz ts);
 extern void pgstat_io_snapshot_cb(void);
@@ -762,7 +790,7 @@ extern void AtEOSubXact_PgStat_Relations(PgStat_SubXactStatus *xact_state, bool
 extern void AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
 extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
 
-extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
+extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only);
 extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
 extern void pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
 
@@ -809,7 +837,7 @@ extern PgStatShared_Common *pgstat_init_entry(PgStat_Kind kind,
  * Functions in pgstat_slru.c
  */
 
-extern bool pgstat_slru_flush_cb(bool nowait);
+extern bool pgstat_slru_flush_cb(bool nowait, bool anytime_only);
 extern void pgstat_slru_init_shmem_cb(void *stats);
 extern void pgstat_slru_reset_all_cb(TimestampTz ts);
 extern void pgstat_slru_snapshot_cb(void);
@@ -820,7 +848,7 @@ extern void pgstat_slru_snapshot_cb(void);
  */
 
 extern void pgstat_wal_init_backend_cb(void);
-extern bool pgstat_wal_flush_cb(bool nowait);
+extern bool pgstat_wal_flush_cb(bool nowait, bool anytime_only);
 extern void pgstat_wal_init_shmem_cb(void *stats);
 extern void pgstat_wal_reset_all_cb(TimestampTz ts);
 extern void pgstat_wal_snapshot_cb(void);
@@ -830,7 +858,7 @@ extern void pgstat_wal_snapshot_cb(void);
  * Functions in pgstat_subscription.c
  */
 
-extern bool pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
+extern bool pgstat_subscription_flush_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only);
 extern void pgstat_subscription_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);

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/test/modules/test_custom_stats/test_custom_var_stats.c b/src/test/modules/test_custom_stats/test_custom_var_stats.c
index 64a8fe63cce..bc0b5d6e0eb 100644
--- a/src/test/modules/test_custom_stats/test_custom_var_stats.c
+++ b/src/test/modules/test_custom_stats/test_custom_var_stats.c
@@ -83,7 +83,7 @@ static dsa_area *custom_stats_description_dsa = NULL;
 
 /* Flush callback: merge pending stats into shared memory */
 static bool test_custom_stats_var_flush_pending_cb(PgStat_EntryRef *entry_ref,
-												   bool nowait);
+												   bool nowait, bool anytime_only);
 
 /* Serialization callback: write auxiliary entry data */
 static void test_custom_stats_var_to_serialized_data(const PgStat_HashKey *key,
@@ -150,7 +150,7 @@ _PG_init(void)
  * Returns false only if nowait=true and lock acquisition fails.
  */
 static bool
-test_custom_stats_var_flush_pending_cb(PgStat_EntryRef *entry_ref, bool nowait)
+test_custom_stats_var_flush_pending_cb(PgStat_EntryRef *entry_ref, bool nowait, bool anytime_only)
 {
 	PgStat_StatCustomVarEntry *pending_entry;
 	PgStatShared_CustomVarEntry *shared_entry;
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 241945734ec..1dbc4b96f51 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2271,6 +2271,7 @@ PgStat_Counter
 PgStat_EntryRef
 PgStat_EntryRefHashEntry
 PgStat_FetchConsistency
+PgStat_FlushMode
 PgStat_FunctionCallUsage
 PgStat_FunctionCounts
 PgStat_HashKey
-- 
2.34.1

--C2xzVbxFmVrP7k6O
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v7-0002-Add-anytime-flush-tests-for-custom-stats.patch"