[PATCH v4 2/3] Adding XID generation count per backend

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[PATCH v4 2/3] Adding XID generation count per backend
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* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


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Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



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* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


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Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


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Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


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Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
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Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
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Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
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	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
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Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
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Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
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	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
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Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
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Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v4 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index f8c4dada7c9..72c8aa7650b 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 47ce61e5093..5e509153656 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 0fdbaf79780..d78633cae44 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v5 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.
---
 src/backend/access/transam/varsup.c         | 4 ++++
 src/backend/utils/activity/pgstat_backend.c | 2 ++
 src/include/pgstat.h                        | 2 ++
 3 files changed, 8 insertions(+)
  43.8% src/backend/access/transam/
  36.6% src/backend/utils/activity/
  19.4% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 1441a051773..fe625d00f7d 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -24,6 +24,7 @@
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "utils/lsyscache.h"
+#include "utils/pgstat_internal.h"
 #include "utils/syscache.h"
 
 
@@ -261,6 +262,9 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		PendingBackendStats.pending_xid_count++;
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 42bfb9cd38f..32ee48eab51 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -287,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	PendingBackendStats.pending_xid_count = 0;
 
 	backend_has_xactstats = false;
 }
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 5d73c4dfbcf..780ca4b3ac0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -525,6 +525,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -543,6 +544,7 @@ typedef struct PgStat_BackendPending
 	 */
 	PgStat_Counter pending_xact_commit;
 	PgStat_Counter pending_xact_rollback;
+	PgStat_Counter pending_xid_count;
 } PgStat_BackendPending;
 
 /*
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0003-Adding-the-pg_stat_backend_transaction-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH v3 2/3] Adding XID generation count per backend
@ 2025-08-08 15:58  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Bertrand Drouvot @ 2025-08-08 15:58 UTC (permalink / raw)

This commit adds a new counter to record the number of XIDs generated per
backend. It will help to detect if a backend is consuming XIDs at a high rate.

Virtual transactions are not taken into account on purpose, we do want to track
only the XID where there is a risk of wraparound.

The counter is not part of PgStat_BackendPending, because we want to avoid
an extra function call in this code path to increment the counter in
PendingBackendStats. The counter increment here behaves more or less the same as
we do for WAL statistics.
---
 src/backend/access/transam/varsup.c         | 2 ++
 src/backend/utils/activity/pgstat_backend.c | 6 +++++-
 src/include/pgstat.h                        | 3 +++
 3 files changed, 10 insertions(+), 1 deletion(-)
  10.1% src/backend/access/transam/
  69.3% src/backend/utils/activity/
  20.5% src/include/

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index fe895787cb7..26c72cbe091 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -21,6 +21,7 @@
 #include "access/xlogutils.h"
 #include "commands/dbcommands.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
@@ -257,6 +258,7 @@ GetNewTransactionId(bool isSubXact)
 		/* LWLockRelease acts as barrier */
 		MyProc->xid = xid;
 		ProcGlobal->xids[MyProc->pgxactoff] = xid;
+		XidGenCount++;
 	}
 	else
 	{
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index bf164854c4b..8b530c510b9 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -52,6 +52,8 @@ static WalUsage prevBackendWalUsage;
  */
 static bool backend_has_xactstats = false;
 
+PgStat_Counter XidGenCount = 0;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -285,9 +287,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
 
 	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
 	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+	shbackendent->stats.xid_count += XidGenCount;
 
 	PendingBackendStats.pending_xact_commit = 0;
 	PendingBackendStats.pending_xact_rollback = 0;
+	XidGenCount = 0;
 
 	backend_has_xactstats = false;
 }
@@ -317,7 +321,7 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		has_pending_data = true;
 
 	/* Some transaction data pending? */
-	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && (backend_has_xactstats || XidGenCount > 0))
 		has_pending_data = true;
 
 	if (!has_pending_data)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9efc0e10ebf..94dd24b3eac 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -492,6 +492,7 @@ typedef struct PgStat_Backend
 	PgStat_WalCounters wal_counters;
 	PgStat_Counter xact_commit;
 	PgStat_Counter xact_rollback;
+	PgStat_Counter xid_count;
 } PgStat_Backend;
 
 /* ---------
@@ -571,6 +572,8 @@ extern PgStat_Backend *pgstat_fetch_stat_backend_by_pid(int pid,
 extern bool pgstat_tracks_backend_bktype(BackendType bktype);
 extern void pgstat_create_backend(ProcNumber procnum);
 
+extern PGDLLIMPORT PgStat_Counter XidGenCount;
+
 /*
  * Functions in pgstat_bgwriter.c
  */
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Adding-the-pg_stat_backend-view.patch"



^ permalink  raw  reply  [nested|flat] 250+ messages in thread

* [PATCH 2/4] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY).
@ 2025-08-11 13:31  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 250+ messages in thread

From: Antonin Houska @ 2025-08-11 13:31 UTC (permalink / raw)

This patch moves the code to index_create_copy() and adds a "concurrently"
parameter so it can be used by REPACK (CONCURRENTLY).

With the CONCURRENTLY option, REPACK cannot simply swap the heap file and
rebuild its indexes. Instead, it needs to build a separate set of indexes
(including system catalog entries) *before* the actual swap, to reduce the
time AccessExclusiveLock needs to be held for.
---
 src/backend/catalog/index.c | 36 ++++++++++++++++++++++++++++--------
 src/include/catalog/index.h |  3 +++
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 3063abff9a5..ff34b1b4269 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1290,15 +1290,31 @@ index_create(Relation heapRelation,
 /*
  * index_concurrently_create_copy
  *
- * Create concurrently an index based on the definition of the one provided by
- * caller.  The index is inserted into catalogs and needs to be built later
- * on.  This is called during concurrent reindex processing.
- *
- * "tablespaceOid" is the tablespace to use for this index.
+ * Variant of index_create_copy(), called during concurrent reindex
+ * processing.
  */
 Oid
 index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							   Oid tablespaceOid, const char *newName)
+{
+	return index_create_copy(heapRelation, oldIndexId, tablespaceOid, newName,
+							 true);
+}
+
+/*
+ * index_create_copy
+ *
+ * Create an index based on the definition of the one provided by caller.  The
+ * index is inserted into catalogs and needs to be built later on.
+ *
+ * "tablespaceOid" is the tablespace to use for this index.
+ *
+ * The actual implementation of index_concurrently_create_copy(), reusable for
+ * other purposes.
+ */
+Oid
+index_create_copy(Relation heapRelation, Oid oldIndexId, Oid tablespaceOid,
+				  const char *newName, bool concurrently)
 {
 	Relation	indexRelation;
 	IndexInfo  *oldInfo,
@@ -1317,6 +1333,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	List	   *indexColNames = NIL;
 	List	   *indexExprs = NIL;
 	List	   *indexPreds = NIL;
+	int		flags = 0;
 
 	indexRelation = index_open(oldIndexId, RowExclusiveLock);
 
@@ -1325,9 +1342,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 
 	/*
 	 * Concurrent build of an index with exclusion constraints is not
-	 * supported.
+	 * supported. If !concurrently, ii_ExclusinOps is currently not needed.
 	 */
-	if (oldInfo->ii_ExclusionOps != NULL)
+	if (oldInfo->ii_ExclusionOps != NULL && concurrently)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("concurrent index creation for exclusion constraints is not supported")));
@@ -1435,6 +1452,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 		stattargets[i].isnull = isnull;
 	}
 
+	if (concurrently)
+		flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT;
+
 	/*
 	 * Now create the new index.
 	 *
@@ -1458,7 +1478,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							  indcoloptions->values,
 							  stattargets,
 							  reloptionsDatum,
-							  INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT,
+							  flags,
 							  0,
 							  true, /* allow table to be a system catalog? */
 							  false,	/* is_internal? */
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index 4daa8bef5ee..fc3e42e5f70 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -99,6 +99,9 @@ extern Oid	index_concurrently_create_copy(Relation heapRelation,
 										   Oid oldIndexId,
 										   Oid tablespaceOid,
 										   const char *newName);
+extern Oid index_create_copy(Relation heapRelation, Oid oldIndexId,
+							 Oid tablespaceOid, const char *newName,
+							 bool concurrently);
 
 extern void index_concurrently_build(Oid heapRelationId,
 									 Oid indexRelationId);
-- 
2.47.1


--=-=-=
Content-Type: text/x-diff
Content-Disposition: attachment;
 filename=v18-0003-Move-conversion-of-a-historic-to-MVCC-snapshot-to-a-.patch



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2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v5 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v4 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-08 15:58 [PATCH v3 2/3] Adding XID generation count per backend Bertrand Drouvot <[email protected]>
2025-08-11 13:31 [PATCH 2/4] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY). Antonin Houska <[email protected]>

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