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[PATCH v3 2/3] Deprecate CREATE MATERIALIZED VIEW IF NOT EXISTS
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* [PATCH v3 2/3] Deprecate CREATE MATERIALIZED VIEW IF NOT EXISTS
@ 2024-05-28 00:19  Erik Wienhold <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Erik Wienhold @ 2024-05-28 00:19 UTC (permalink / raw)

---
 src/backend/parser/gram.y                     | 14 +++++++++++++
 .../expected/test_extensions.out              | 18 +++++++++++++++++
 src/test/regress/expected/matview.out         | 20 +++++++++++++++++++
 3 files changed, 52 insertions(+)

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index b02b2f42d2..4b939ea7ca 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4778,6 +4778,20 @@ CreateMatViewStmt:
 					$8->rel->relpersistence = $2;
 					$8->skipData = !($11);
 					$$ = (Node *) ctas;
+
+					if (ctas->into->rel->schemaname)
+							ereport(WARNING,
+									errmsg("IF NOT EXISTS is deprecated in materialized view creation"),
+									errhint("Use CREATE OR REPLACE MATERIALIZED VIEW %s.%s.",
+											ctas->into->rel->schemaname,
+											ctas->into->rel->relname),
+									parser_errposition(@1));
+					else
+							ereport(WARNING,
+									errmsg("IF NOT EXISTS is deprecated in materialized view creation"),
+									errhint("Use CREATE OR REPLACE MATERIALIZED VIEW %s.",
+											ctas->into->rel->relname),
+									parser_errposition(@1));
 				}
 		| CREATE OR REPLACE OptNoLog MATERIALIZED VIEW create_mv_target AS SelectStmt opt_with_data
 				{
diff --git a/src/test/modules/test_extensions/expected/test_extensions.out b/src/test/modules/test_extensions/expected/test_extensions.out
index f357cc21aa..ecd453b29d 100644
--- a/src/test/modules/test_extensions/expected/test_extensions.out
+++ b/src/test/modules/test_extensions/expected/test_extensions.out
@@ -377,41 +377,57 @@ Objects in extension "test_ext_cor"
 CREATE COLLATION ext_cine_coll
   ( LC_COLLATE = "C", LC_CTYPE = "C" );
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  collation ext_cine_coll is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP COLLATION ext_cine_coll;
 CREATE MATERIALIZED VIEW ext_cine_mv AS SELECT 11 AS f1;
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  materialized view ext_cine_mv is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP MATERIALIZED VIEW ext_cine_mv;
 CREATE FOREIGN DATA WRAPPER dummy;
 CREATE SERVER ext_cine_srv FOREIGN DATA WRAPPER dummy;
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  server ext_cine_srv is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP SERVER ext_cine_srv;
 CREATE SCHEMA ext_cine_schema;
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  schema ext_cine_schema is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP SCHEMA ext_cine_schema;
 CREATE SEQUENCE ext_cine_seq;
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  sequence ext_cine_seq is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP SEQUENCE ext_cine_seq;
 CREATE TABLE ext_cine_tab1 (x int);
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  table ext_cine_tab1 is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP TABLE ext_cine_tab1;
 CREATE TABLE ext_cine_tab2 AS SELECT 42 AS y;
 CREATE EXTENSION test_ext_cine;  -- fail
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 ERROR:  table ext_cine_tab2 is not a member of extension "test_ext_cine"
 DETAIL:  An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns.
 DROP TABLE ext_cine_tab2;
 CREATE EXTENSION test_ext_cine;
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 \dx+ test_ext_cine
 Objects in extension "test_ext_cine"
         Object description         
@@ -433,6 +449,8 @@ Objects in extension "test_ext_cine"
 (14 rows)
 
 ALTER EXTENSION test_ext_cine UPDATE TO '1.1';
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW ext_cine_mv.
 \dx+ test_ext_cine
 Objects in extension "test_ext_cine"
         Object description         
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index e2e2a13396..cefd0d442c 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -565,6 +565,10 @@ CREATE MATERIALIZED VIEW mvtest_mv_foo AS SELECT * FROM mvtest_foo_data;
 CREATE MATERIALIZED VIEW mvtest_mv_foo AS SELECT * FROM mvtest_foo_data;
 ERROR:  relation "mvtest_mv_foo" already exists
 CREATE MATERIALIZED VIEW IF NOT EXISTS mvtest_mv_foo AS SELECT * FROM mvtest_foo_data;
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+LINE 1: CREATE MATERIALIZED VIEW IF NOT EXISTS mvtest_mv_foo AS SELE...
+        ^
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW mvtest_mv_foo.
 NOTICE:  relation "mvtest_mv_foo" already exists, skipping
 CREATE UNIQUE INDEX ON mvtest_mv_foo (i);
 RESET ROLE;
@@ -662,12 +666,20 @@ CREATE MATERIALIZED VIEW matview_ine_tab AS SELECT 1 / 0; -- error
 ERROR:  relation "matview_ine_tab" already exists
 CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
   SELECT 1 / 0; -- ok
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+LINE 1: CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
+        ^
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW matview_ine_tab.
 NOTICE:  relation "matview_ine_tab" already exists, skipping
 CREATE MATERIALIZED VIEW matview_ine_tab AS
   SELECT 1 / 0 WITH NO DATA; -- error
 ERROR:  relation "matview_ine_tab" already exists
 CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
   SELECT 1 / 0 WITH NO DATA; -- ok
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+LINE 1: CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
+        ^
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW matview_ine_tab.
 NOTICE:  relation "matview_ine_tab" already exists, skipping
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
   CREATE MATERIALIZED VIEW matview_ine_tab AS
@@ -676,6 +688,10 @@ ERROR:  relation "matview_ine_tab" already exists
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0; -- ok
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+LINE 2:   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
+          ^
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW matview_ine_tab.
 NOTICE:  relation "matview_ine_tab" already exists, skipping
  QUERY PLAN 
 ------------
@@ -688,6 +704,10 @@ ERROR:  relation "matview_ine_tab" already exists
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
     SELECT 1 / 0 WITH NO DATA; -- ok
+WARNING:  IF NOT EXISTS is deprecated in materialized view creation
+LINE 2:   CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
+          ^
+HINT:  Use CREATE OR REPLACE MATERIALIZED VIEW matview_ine_tab.
 NOTICE:  relation "matview_ine_tab" already exists, skipping
  QUERY PLAN 
 ------------
-- 
2.46.0


--muysnh7l3kienazz
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0003-Replace-matview-WITH-OLD-DATA.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v4 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..47ce61e5093 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -36,7 +36,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index b31f20d41bc..400a8c5d734 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -342,6 +342,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..0fdbaf79780 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -801,6 +809,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..b97184c6539 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,7 +616,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--jg9kqX3osLGO+8A7
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v4-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v5 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. The new pending counters are updated when the database ones are
flushed (to reduce the overhead of incrementing new counters).
---
 src/backend/utils/activity/pgstat_backend.c  | 42 +++++++++++++++++++-
 src/backend/utils/activity/pgstat_database.c |  7 ++++
 src/include/pgstat.h                         | 15 +++++++
 src/include/utils/pgstat_internal.h          |  3 +-
 4 files changed, 65 insertions(+), 2 deletions(-)
  74.4% src/backend/utils/activity/
   7.8% src/include/utils/
  17.7% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 7727fed3bda..42bfb9cd38f 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -37,7 +37,7 @@
  * reported within critical sections so we use static memory in order to avoid
  * memory allocation.
  */
-static PgStat_BackendPending PendingBackendStats;
+PgStat_BackendPending PendingBackendStats;
 static bool backend_has_iostats = false;
 
 /*
@@ -48,6 +48,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+bool		backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -261,6 +266,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -285,6 +318,10 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -300,6 +337,9 @@ pgstat_flush_backend(bool nowait, uint32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index 933dcb5cae5..218ff5e653c 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -352,6 +352,13 @@ pgstat_update_dbstats(TimestampTz ts)
 	dbentry->blk_read_time += pgStatBlockReadTime;
 	dbentry->blk_write_time += pgStatBlockWriteTime;
 
+	/* Do the same for backend stats */
+	PendingBackendStats.pending_xact_commit += pgStatXactCommit;
+	PendingBackendStats.pending_xact_rollback += pgStatXactRollback;
+
+	backend_has_xactstats = true;
+	pgstat_report_fixed = true;
+
 	if (pgstat_should_report_connstat())
 	{
 		long		secs;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..5d73c4dfbcf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -523,6 +523,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -535,6 +537,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
@@ -844,6 +852,13 @@ extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
 
+/*
+ * Variables in pgstat_backend.c
+ */
+
+extern PGDLLIMPORT PgStat_BackendPending PendingBackendStats;
+extern PGDLLIMPORT bool backend_has_xactstats;
+
 /*
  * Variables in pgstat_bgwriter.c
  */
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..8077c65e938 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -707,7 +707,8 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, uint32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
-- 
2.34.1


--uN5gGi2rtCNSVbpC
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v5-0002-Adding-XID-generation-count-per-backend.patch"



^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v1] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  2 +
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 160 insertions(+), 1 deletion(-)
  26.9% doc/src/sgml/
  29.1% src/backend/utils/activity/
  12.3% src/backend/utils/adt/
   9.7% src/include/catalog/
   4.0% src/include/utils/
   9.2% src/test/regress/expected/
   7.3% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fa78031ccbb..ef89683164f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..7cec0c83071 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,13 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static int	pgStatBackendXactCommit = 0;
+static int	pgStatBackendXactRollback = 0;
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +266,33 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += pgStatBackendXactCommit;
+	shbackendent->stats.xact_rollback += pgStatBackendXactRollback;
+
+	pgStatBackendXactCommit = pgStatBackendXactRollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +317,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +336,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +441,22 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			pgStatBackendXactCommit++;
+		else
+			pgStatBackendXactRollback++;
+
+		backend_has_xactstats = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..4c9f6b0dcec 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--ZnbSmJtA6EgjuGCe--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v2] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

This commit adds 2 functions: pg_stat_get_backend_xact_commit() and
pg_stat_get_backend_xact_rollback() to report the number of transactions that
have been committed/rolled back for a given backend PID.

It relies on the existing per backend statistics that has been added in
9aea73fc61d.
---
 doc/src/sgml/monitoring.sgml                | 36 +++++++++++++
 src/backend/utils/activity/pgstat_backend.c | 60 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/backend/utils/adt/pgstatfuncs.c         | 22 ++++++++
 src/include/catalog/pg_proc.dat             |  9 ++++
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 src/test/regress/expected/stats.out         | 17 ++++++
 src/test/regress/sql/stats.sql              | 10 ++++
 9 files changed, 166 insertions(+), 1 deletion(-)
  26.1% doc/src/sgml/
  29.1% src/backend/utils/activity/
  11.9% src/backend/utils/adt/
   9.4% src/include/catalog/
   3.9% src/include/utils/
   3.3% src/include/
   8.9% src/test/regress/expected/
   7.1% src/test/regress/sql/

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..77b41e02b82 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -4921,6 +4921,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        </para></entry>
       </row>
 
+      <row>
+       <entry id="pg-stat-get-backend-xact-commit" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_commit</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_commit</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been committed by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
+      <row>
+       <entry id="pg-stat-get-backend-xact-rollback" role="func_table_entry"><para role="func_signature">
+        <indexterm>
+         <primary>pg_stat_get_backend_xact_rollback</primary>
+        </indexterm>
+        <function>pg_stat_get_backend_xact_rollback</function> ( <type>integer</type> )
+        <returnvalue>bigint</returnvalue>
+       </para>
+       <para>
+        Returns the number of transactions that have been rolled back by the backend
+        with the specified process ID.
+       </para>
+       <para>
+        The function does not return statistics for the checkpointer,
+        the background writer, the startup process and the autovacuum launcher.
+       </para></entry>
+      </row>
+
       <row>
        <entry id="pg-stat-get-backend-wal" role="func_table_entry"><para role="func_signature">
         <indexterm>
diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..12ae9a8d321 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend xact statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * XACT statistics.  In this case, avoid unnecessarily modifying the stats
+	 * entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some XACT data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,23 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/*
+		 * Count transaction commit or abort.  (We use counters, not just
+		 * bools, in case the reporting message isn't sent right away.)
+		 */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..6436129f516 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1606,6 +1606,28 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS)
 	return (Datum) 0;
 }
 
+#define PG_STAT_GET_BACKENDENTRY_INT64(stat)					\
+Datum															\
+CppConcat(pg_stat_get_backend_,stat)(PG_FUNCTION_ARGS)			\
+{																\
+	int			pid;											\
+	PgStat_Backend *backend_stats;								\
+																\
+	pid = PG_GETARG_INT32(0);									\
+	backend_stats = pgstat_fetch_stat_backend_by_pid(pid, NULL);\
+																\
+	if (!backend_stats)											\
+		PG_RETURN_NULL();										\
+	else														\
+		PG_RETURN_INT64(backend_stats->stat);					\
+}
+
+/* pg_stat_get_backend_xact_commit */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_commit)
+
+/* pg_stat_get_backend_xact_rollback */
+PG_STAT_GET_BACKENDENTRY_INT64(xact_rollback)
+
 /*
  * pg_stat_wal_build_tuple
  *
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..f5085d4e016 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6010,6 +6010,15 @@
   proargnames => '{backend_pid,backend_type,object,context,reads,read_bytes,read_time,writes,write_bytes,write_time,writebacks,writeback_time,extends,extend_bytes,extend_time,hits,evictions,reuses,fsyncs,fsync_time,stats_reset}',
   prosrc => 'pg_stat_get_backend_io' },
 
+{ oid => '8170', descr => 'statistics: backend transactions committed',
+  proname => 'pg_stat_get_backend_xact_commit', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_commit' },
+{ oid => '8916', descr => 'statistics: backend transactions rolled back',
+  proname => 'pg_stat_get_backend_xact_rollback', provolatile => 's',
+  proparallel => 'r', prorettype => 'int8', proargtypes => 'int4',
+  prosrc => 'pg_stat_get_backend_xact_rollback' },
+
 { oid => '1136', descr => 'statistics: information about WAL activity',
   proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..d3491faaff2 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Xact statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..0d316f94e40 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -135,11 +135,28 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush 
+--------------------------
+ 
+(1 row)
+
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+SELECT :xact_commit_after > :xact_commit_before;
+ ?column? 
+----------
+ t
+(1 row)
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 54e72866344..d629140d880 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -58,12 +58,22 @@ INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 UPDATE trunc_stats_test1 SET id = id + 10 WHERE id IN (1, 2);
 DELETE FROM trunc_stats_test1 WHERE id = 3;
 
+-- in passing, check that backend's commit is incrementing
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_before
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
 BEGIN;
 UPDATE trunc_stats_test1 SET id = id + 100;
 TRUNCATE trunc_stats_test1;
 INSERT INTO trunc_stats_test1 DEFAULT VALUES;
 COMMIT;
 
+SELECT pg_stat_force_next_flush();
+SELECT pg_stat_get_backend_xact_commit AS xact_commit_after
+  FROM pg_stat_get_backend_xact_commit(pg_backend_pid()) \gset
+
+SELECT :xact_commit_after > :xact_commit_before;
+
 -- use a savepoint: 1 insert, 1 live
 BEGIN;
 INSERT INTO trunc_stats_test2 DEFAULT VALUES;
-- 
2.34.1


--SywurcztURg2uk+W--





^ permalink  raw  reply  [nested|flat] 1033+ messages in thread

* [PATCH v3 1/3] Adding per backend commit and rollback counters
@ 2025-08-04 08:14  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 1033+ messages in thread

From: Bertrand Drouvot @ 2025-08-04 08:14 UTC (permalink / raw)

It relies on the existing per backend statistics that has been added in
9aea73fc61d. A new function is called in AtEOXact_PgStat() to increment those
two new counters.
---
 src/backend/utils/activity/pgstat_backend.c | 57 +++++++++++++++++++++
 src/backend/utils/activity/pgstat_xact.c    |  1 +
 src/include/pgstat.h                        |  8 +++
 src/include/utils/pgstat_internal.h         |  4 +-
 4 files changed, 69 insertions(+), 1 deletion(-)
  78.9% src/backend/utils/activity/
  11.2% src/include/utils/
   9.8% src/include/

diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c
index 8714a85e2d9..bf164854c4b 100644
--- a/src/backend/utils/activity/pgstat_backend.c
+++ b/src/backend/utils/activity/pgstat_backend.c
@@ -47,6 +47,11 @@ static bool backend_has_iostats = false;
  */
 static WalUsage prevBackendWalUsage;
 
+/*
+ * For backend commit and rollback statistics.
+ */
+static bool backend_has_xactstats = false;
+
 /*
  * Utility routines to report I/O stats for backends, kept here to avoid
  * exposing PendingBackendStats to the outside world.
@@ -259,6 +264,34 @@ pgstat_flush_backend_entry_wal(PgStat_EntryRef *entry_ref)
 	prevBackendWalUsage = pgWalUsage;
 }
 
+/*
+ * Flush out locally pending backend transaction statistics.  Locking is managed
+ * by the caller.
+ */
+static void
+pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref)
+{
+	PgStatShared_Backend *shbackendent;
+
+	/*
+	 * This function can be called even if nothing at all has happened for
+	 * transaction statistics.  In this case, avoid unnecessarily modifying
+	 * the stats entry.
+	 */
+	if (!backend_has_xactstats)
+		return;
+
+	shbackendent = (PgStatShared_Backend *) entry_ref->shared_stats;
+
+	shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit;
+	shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback;
+
+	PendingBackendStats.pending_xact_commit = 0;
+	PendingBackendStats.pending_xact_rollback = 0;
+
+	backend_has_xactstats = false;
+}
+
 /*
  * Flush out locally pending backend statistics
  *
@@ -283,6 +316,10 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 		pgstat_backend_wal_have_pending())
 		has_pending_data = true;
 
+	/* Some transaction data pending? */
+	if ((flags & PGSTAT_BACKEND_FLUSH_XACT) && backend_has_xactstats)
+		has_pending_data = true;
+
 	if (!has_pending_data)
 		return false;
 
@@ -298,6 +335,9 @@ pgstat_flush_backend(bool nowait, bits32 flags)
 	if (flags & PGSTAT_BACKEND_FLUSH_WAL)
 		pgstat_flush_backend_entry_wal(entry_ref);
 
+	if (flags & PGSTAT_BACKEND_FLUSH_XACT)
+		pgstat_flush_backend_entry_xact(entry_ref);
+
 	pgstat_unlock_entry(entry_ref);
 
 	return false;
@@ -400,3 +440,20 @@ pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
 {
 	((PgStatShared_Backend *) header)->stats.stat_reset_timestamp = ts;
 }
+
+void
+AtEOXact_PgStat_Backend(bool isCommit, bool parallel)
+{
+	/* Don't count parallel worker transaction stats */
+	if (!parallel)
+	{
+		/* Count transaction commit or abort */
+		if (isCommit)
+			PendingBackendStats.pending_xact_commit++;
+		else
+			PendingBackendStats.pending_xact_rollback++;
+
+		backend_has_xactstats = true;
+		pgstat_report_fixed = true;
+	}
+}
diff --git a/src/backend/utils/activity/pgstat_xact.c b/src/backend/utils/activity/pgstat_xact.c
index bc9864bd8d9..cd1c501c165 100644
--- a/src/backend/utils/activity/pgstat_xact.c
+++ b/src/backend/utils/activity/pgstat_xact.c
@@ -42,6 +42,7 @@ AtEOXact_PgStat(bool isCommit, bool parallel)
 	PgStat_SubXactStatus *xact_state;
 
 	AtEOXact_PgStat_Database(isCommit, parallel);
+	AtEOXact_PgStat_Backend(isCommit, parallel);
 
 	/* handle transactional stats information */
 	xact_state = pgStatXactStack;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9efc0e10ebf 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -490,6 +490,8 @@ typedef struct PgStat_Backend
 	TimestampTz stat_reset_timestamp;
 	PgStat_BktypeIO io_stats;
 	PgStat_WalCounters wal_counters;
+	PgStat_Counter xact_commit;
+	PgStat_Counter xact_rollback;
 } PgStat_Backend;
 
 /* ---------
@@ -502,6 +504,12 @@ typedef struct PgStat_BackendPending
 	 * Backend statistics store the same amount of IO data as PGSTAT_KIND_IO.
 	 */
 	PgStat_PendingIO pending_io;
+
+	/*
+	 * Transaction statistics pending flush.
+	 */
+	PgStat_Counter pending_xact_commit;
+	PgStat_Counter pending_xact_rollback;
 } PgStat_BackendPending;
 
 /*
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 6cf00008f63..23ea8ffd618 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -616,12 +616,14 @@ extern void pgstat_archiver_snapshot_cb(void);
 /* flags for pgstat_flush_backend() */
 #define PGSTAT_BACKEND_FLUSH_IO		(1 << 0)	/* Flush I/O statistics */
 #define PGSTAT_BACKEND_FLUSH_WAL   (1 << 1) /* Flush WAL statistics */
-#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL)
+#define PGSTAT_BACKEND_FLUSH_XACT   (1 << 2)	/* Flush xact statistics */
+#define PGSTAT_BACKEND_FLUSH_ALL   (PGSTAT_BACKEND_FLUSH_IO | PGSTAT_BACKEND_FLUSH_WAL | PGSTAT_BACKEND_FLUSH_XACT)
 
 extern bool pgstat_flush_backend(bool nowait, bits32 flags);
 extern bool pgstat_backend_flush_cb(bool nowait);
 extern void pgstat_backend_reset_timestamp_cb(PgStatShared_Common *header,
 											  TimestampTz ts);
+extern void AtEOXact_PgStat_Backend(bool isCommit, bool parallel);
 
 /*
  * Functions in pgstat_bgwriter.c
-- 
2.34.1


--u6+Li7FU79Mt/lVd
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
	filename="v3-0002-Adding-XID-generation-count-per-backend.patch"



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