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* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v4 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 57 +++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 223 insertions(+)
51.7% doc/src/sgml/
3.2% src/backend/catalog/
23.1% src/backend/utils/adt/
7.0% src/include/catalog/
9.6% src/test/regress/expected/
5.1% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..025641c2f70 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1172,6 +1186,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -4921,6 +5020,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 1b3c5a55882..ee3f653f360 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -911,6 +911,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..fa92099e789 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -685,6 +685,63 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ backend_stats = pgstat_fetch_stat_backend_by_pid(beentry->st_procpid, NULL);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 118d6da1ace..24ec3d861a2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5641,6 +5641,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..ae376f96998 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1847,6 +1847,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 605f5070376..7079198bc06 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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..0d6a408c7b5 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--jg9kqX3osLGO+8A7--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v5 3/3] Adding the pg_stat_backend_transaction view
@ 2025-08-09 14:22 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-08-09 14:22 UTC (permalink / raw)
This view displays one row per server process, showing transaction statistics
related to the current activity of that process. It currently displays the pid,
the number of XIDs generated, the number of commits, the number of rollbacks and
the time at which these statistics were last reset.
It's built on top of a new function (pg_stat_get_backend_transactions()). The idea
is the same as pg_stat_activity and pg_stat_get_activity().
Adding documentation and tests.
XXX: Bump catversion
---
doc/src/sgml/monitoring.sgml | 115 +++++++++++++++++++++++++++
src/backend/catalog/system_views.sql | 9 +++
src/backend/utils/adt/pgstatfuncs.c | 65 +++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 6 ++
src/test/regress/expected/stats.out | 17 ++++
src/test/regress/sql/stats.sql | 10 +++
7 files changed, 231 insertions(+)
49.8% doc/src/sgml/
3.1% src/backend/catalog/
25.8% src/backend/utils/adt/
6.8% src/include/catalog/
9.2% src/test/regress/expected/
4.9% src/test/regress/sql/
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index bb75ed1069b..86200553293 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -320,6 +320,20 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry>
+ <structname>pg_stat_backend_transaction</structname>
+ <indexterm><primary>pg_stat_backend_transaction</primary></indexterm>
+ </entry>
+ <entry>
+ One row per server process, showing statistics related to
+ the current activity of that process, such as number of commits and
+ rollbacks.
+ See <link linkend="monitoring-pg-stat-backend-transaction-view">
+ <structname>pg_stat_backend_transaction</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_replication</structname><indexterm><primary>pg_stat_replication</primary></indexterm></entry>
<entry>One row per WAL sender process, showing statistics about
@@ -1195,6 +1209,91 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</note>
</sect2>
+ <sect2 id="monitoring-pg-stat-backend-transaction-view">
+ <title><structname>pg_stat_backend_transaction</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_backend_transaction</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_backend_transaction</structname> view will have one row
+ per server process, showing statistics related to
+ the current activity of that process.
+ </para>
+
+ <table id="pg-stat-backend-transaction-view" xreflabel="pg_stat_backend_transaction">
+ <title><structname>pg_stat_backend_transaction</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>pid</structfield> <type>integer</type>
+ </para>
+ <para>
+ Process ID of this backend
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xid_count</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of XID that have been generated by the backend. It does not take
+ into account virtual transaction ID on purpose.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_commit</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been committed.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>xact_rollback</structfield> <type>bigint</type>
+ </para>
+ <para>
+ The number of transactions that have been rolled back.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <note>
+ <para>
+ The view does not return statistics for the checkpointer,
+ the background writer, the startup process and the autovacuum launcher.
+ </para>
+ </note>
+ </sect2>
+
<sect2 id="monitoring-pg-stat-replication-view">
<title><structname>pg_stat_replication</structname></title>
@@ -5342,6 +5441,22 @@ description | Waiting for a newly initialized WAL file to reach durable storage
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_stat_get_backend_transactions</primary>
+ </indexterm>
+ <function>pg_stat_get_backend_transactions</function> ( <type>integer</type> )
+ <returnvalue>setof record</returnvalue>
+ </para>
+ <para>
+ Returns a record of transaction statistics about the backend with the
+ specified process ID, or one record for each active backend in the system
+ if <literal>NULL</literal> is specified. The fields returned are a
+ subset of those in the <structname>pg_stat_backend_transaction</structname> view.
+ </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/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index e54018004db..e005eaeb579 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -946,6 +946,15 @@ CREATE VIEW pg_stat_activity AS
LEFT JOIN pg_database AS D ON (S.datid = D.oid)
LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
+CREATE VIEW pg_stat_backend_transaction AS
+ SELECT
+ S.pid,
+ S.xid_count,
+ S.xact_commit,
+ S.xact_rollback,
+ S.stats_reset
+ FROM pg_stat_get_backend_transactions(NULL) AS S;
+
CREATE VIEW pg_stat_replication AS
SELECT
S.pid,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..77ee9222ccf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -708,6 +708,71 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
return (Datum) 0;
}
+/*
+ * Returns transactions statistics of PG backends.
+ */
+Datum
+pg_stat_get_backend_transactions(PG_FUNCTION_ARGS)
+{
+#define PG_STAT_GET_BACKEND_STATS_COLS 5
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ InitMaterializedSRF(fcinfo, 0);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+ {
+ /* for each row */
+ Datum values[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ bool nulls[PG_STAT_GET_BACKEND_STATS_COLS] = {0};
+ LocalPgBackendStatus *local_beentry;
+ PgBackendStatus *beentry;
+ PgStat_Backend *backend_stats;
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_get_local_beentry_by_index(curr_backend);
+ beentry = &local_beentry->backendStatus;
+
+ /* If looking for specific PID, ignore all the others */
+ if (pid != -1 && beentry->st_procpid != pid)
+ continue;
+
+ /* check if the backend type tracks statistics */
+ if (!pgstat_tracks_backend_bktype(beentry->st_backendType))
+ continue;
+
+ /*
+ * Don't use pgstat_fetch_stat_backend_by_pid() to avoid holding the
+ * ProcArrayLock during each iteration.
+ */
+ backend_stats = pgstat_fetch_stat_backend(local_beentry->proc_number);
+
+ values[0] = Int32GetDatum(beentry->st_procpid);
+
+ if (!backend_stats)
+ continue;
+
+ values[1] = Int64GetDatum(backend_stats->xid_count);
+ values[2] = Int64GetDatum(backend_stats->xact_commit);
+ values[3] = Int64GetDatum(backend_stats->xact_rollback);
+
+ if (backend_stats->stat_reset_timestamp != 0)
+ values[4] = TimestampTzGetDatum(backend_stats->stat_reset_timestamp);
+ else
+ nulls[4] = true;
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
+ }
+
+ return (Datum) 0;
+}
Datum
pg_backend_pid(PG_FUNCTION_ARGS)
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3579cec5744..6a686e93fdd 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5680,6 +5680,15 @@
proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
proargnames => '{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,ssl_client_dn,ssl_client_serial,ssl_issuer_dn,gss_auth,gss_princ,gss_enc,gss_delegation,leader_pid,query_id}',
prosrc => 'pg_stat_get_activity' },
+{ oid => '9555',
+ descr => 'statistics: statistics about currently active backends',
+ proname => 'pg_stat_get_backend_transactions', prorows => '100', proisstrict => 'f',
+ proretset => 't', provolatile => 's', proparallel => 'r',
+ prorettype => 'record', proargtypes => 'int4',
+ proallargtypes => '{int4,int4,int8,int8,int8,timestamptz}',
+ proargmodes => '{i,o,o,o,o,o}',
+ proargnames => '{pid,pid,xid_count,xact_commit,xact_rollback,stats_reset}',
+ prosrc => 'pg_stat_get_backend_transactions' },
{ oid => '6318', descr => 'describe wait events',
proname => 'pg_get_wait_events', procost => '10', prorows => '250',
proretset => 't', provolatile => 'v', prorettype => 'record',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2b3cf6d8569..2b4ea519677 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1860,6 +1860,12 @@ pg_stat_archiver| SELECT archived_count,
last_failed_time,
stats_reset
FROM pg_stat_get_archiver() s(archived_count, last_archived_wal, last_archived_time, failed_count, last_failed_wal, last_failed_time, stats_reset);
+pg_stat_backend_transaction| SELECT pid,
+ xid_count,
+ xact_commit,
+ xact_rollback,
+ stats_reset
+ FROM pg_stat_get_backend_transactions(NULL::integer) s(pid, xid_count, xact_commit, xact_rollback, stats_reset);
pg_stat_bgwriter| SELECT pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
pg_stat_get_buf_alloc() AS buffers_alloc,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index ea7f7846895..e3f55a4c0ea 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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 65d8968c83e..e6b35593a95 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 xact_commit AS xact_commit_before
+ FROM pg_stat_backend_transaction WHERE pid = 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 xact_commit AS xact_commit_after
+ FROM pg_stat_backend_transaction WHERE pid = 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
--uN5gGi2rtCNSVbpC--
^ permalink raw reply [nested|flat] 339+ messages in thread
* [PATCH v15 1/2] Key PGSTAT_KIND_RELATION by relfile locator
@ 2025-10-01 09:45 Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 339+ messages in thread
From: Bertrand Drouvot @ 2025-10-01 09:45 UTC (permalink / raw)
This patch changes the key used for the PGSTAT_KIND_RELATION statistic kind.
Instead of the relation oid, it now relies on:
- dboid (linked to RelFileLocator's dbOid)
- objoid which is the result of a new macro (namely RelFileLocatorToPgStatObjid())
that computes an objoid based on the RelFileLocator's spcOid and the
RelFileLocator's relNumber.
This is possible as, since b14e9ce7d55c, the objoid is now uint64 and spcOid
and relNumber are 32 bits.
That will allow us to add new stats (add writes counters) and ensure that some
counters (n_dead_tup and friends) are replicated.
The patch introduces pgstat_reloid_to_relfilelocator() to 1) avoid calling
RelationIdGetRelation() to get the relfilelocator based on the relation oid
and 2) handle the partitioned table case.
Please note that:
- when running pg_stat_have_stats('relation',...) we now need to be connected
to the database that hosts the relation. As pg_stat_have_stats() is not
documented publicly, then the changes done in 029_stats_restart.pl look
enough.
- this patch does not handle rewrites so some tests are failing. It's only
intent is to ease the review and should not be pushed without being
merged with the following patch that handles the rewrites.
- it can be used to test that stats are incremented correctly and that we're
able to retrieve them as long as rewrites are not involved.
---
src/backend/postmaster/autovacuum.c | 18 +-
src/backend/utils/activity/pgstat_relation.c | 236 ++++++++++++++++---
src/backend/utils/adt/pgstatfuncs.c | 21 +-
src/include/catalog/pg_tablespace.dat | 4 +
src/include/catalog/pg_tablespace.h | 8 +
src/include/pgstat.h | 15 +-
src/include/utils/pgstat_internal.h | 1 +
src/test/recovery/t/029_stats_restart.pl | 40 ++--
8 files changed, 272 insertions(+), 71 deletions(-)
6.2% src/backend/postmaster/
61.7% src/backend/utils/activity/
4.9% src/backend/utils/adt/
3.2% src/include/catalog/
5.6% src/include/
18.1% src/test/recovery/t/
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index d695f1de4bd..0a028b18d66 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2035,6 +2035,7 @@ do_autovacuum(void)
bool doanalyze;
bool wraparound;
AutoVacuumScores scores;
+ RelFileLocator locator;
if (classForm->relkind != RELKIND_RELATION &&
classForm->relkind != RELKIND_MATVIEW)
@@ -2042,6 +2043,10 @@ do_autovacuum(void)
relid = classForm->oid;
+ locator.dbOid = classForm->relisshared ? InvalidOid : MyDatabaseId;
+ locator.spcOid = classForm->reltablespace;
+ locator.relNumber = classForm->relfilenode;
+
/*
* Check if it is a temp table (presumably, of some other backend's).
* We cannot safely process other backends' temp tables.
@@ -2069,8 +2074,7 @@ do_autovacuum(void)
/* Fetch reloptions and the pgstat entry for this table */
relopts = extract_autovac_opts(tuple, pg_class_desc);
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_by_locator(locator);
/* Check if it needs vacuum or analyze */
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
@@ -2143,6 +2147,7 @@ do_autovacuum(void)
bool doanalyze;
bool wraparound;
AutoVacuumScores scores;
+ RelFileLocator locator;
/*
* We cannot safely process other backends' temp tables, so skip 'em.
@@ -2151,6 +2156,9 @@ do_autovacuum(void)
continue;
relid = classForm->oid;
+ locator.dbOid = classForm->relisshared ? InvalidOid : MyDatabaseId;
+ locator.spcOid = classForm->reltablespace;
+ locator.relNumber = classForm->relfilenode;
/*
* fetch reloptions -- if this toast table does not have them, try the
@@ -2170,8 +2178,7 @@ do_autovacuum(void)
}
/* Fetch the pgstat entry for this table */
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_by_locator(locator);
relation_needs_vacanalyze(relid, relopts, classForm, tabentry,
effective_multixact_freeze_max_age,
@@ -2988,8 +2995,7 @@ recheck_relation_needs_vacanalyze(Oid relid,
AutoVacuumScores scores;
/* fetch the pgstat table entry */
- tabentry = pgstat_fetch_stat_tabentry_ext(classForm->relisshared,
- relid);
+ tabentry = pgstat_fetch_stat_tabentry_ext(relid);
relation_needs_vacanalyze(relid, avopts, classForm, tabentry,
effective_multixact_freeze_max_age,
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index bc8c43b96aa..89bf0cbed56 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -17,12 +17,17 @@
#include "postgres.h"
+#include "access/htup_details.h"
#include "access/twophase_rmgr.h"
#include "access/xact.h"
#include "catalog/catalog.h"
+#include "catalog/pg_tablespace.h"
+#include "storage/lmgr.h"
#include "utils/memutils.h"
#include "utils/pgstat_internal.h"
#include "utils/rel.h"
+#include "utils/relmapper.h"
+#include "utils/syscache.h"
#include "utils/timestamp.h"
@@ -36,13 +41,12 @@ typedef struct TwoPhasePgStatRecord
PgStat_Counter inserted_pre_truncdrop;
PgStat_Counter updated_pre_truncdrop;
PgStat_Counter deleted_pre_truncdrop;
- Oid id; /* table's OID */
- bool shared; /* is it a shared catalog? */
+ RelFileLocator locator; /* table's rd_locator */
bool truncdropped; /* was the relation truncated/dropped? */
} TwoPhasePgStatRecord;
-static PgStat_TableStatus *pgstat_prep_relation_pending(Oid rel_id, bool isshared);
+static PgStat_TableStatus *pgstat_prep_relation_pending(RelFileLocator locator);
static void add_tabstat_xact_level(PgStat_TableStatus *pgstat_info, int nest_level);
static void ensure_tabstat_xact_level(PgStat_TableStatus *pgstat_info);
static void save_truncdrop_counters(PgStat_TableXactStatus *trans, bool is_drop);
@@ -60,8 +64,7 @@ pgstat_copy_relation_stats(Relation dst, Relation src)
PgStatShared_Relation *dstshstats;
PgStat_EntryRef *dst_ref;
- srcstats = pgstat_fetch_stat_tabentry_ext(src->rd_rel->relisshared,
- RelationGetRelid(src));
+ srcstats = pgstat_fetch_stat_tabentry_ext(RelationGetRelid(src));
if (!srcstats)
return;
@@ -94,8 +97,10 @@ pgstat_init_relation(Relation rel)
/*
* We only count stats for relations with storage and partitioned tables
+ * and we don't count stats generated during a rewrite.
*/
- if (!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE)
+ if ((!RELKIND_HAS_STORAGE(relkind) && relkind != RELKIND_PARTITIONED_TABLE) ||
+ OidIsValid(rel->rd_rel->relrewrite))
{
rel->pgstat_enabled = false;
rel->pgstat_info = NULL;
@@ -130,12 +135,37 @@ pgstat_init_relation(Relation rel)
void
pgstat_assoc_relation(Relation rel)
{
+ RelFileLocator locator;
+
Assert(rel->pgstat_enabled);
Assert(rel->pgstat_info == NULL);
+ /*
+ * Don't associate stats for relations without storage and non partitioned
+ * tables.
+ */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind) &&
+ rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ return;
+
+ if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ locator = rel->rd_locator;
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+ locator.spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator.relNumber = rel->rd_id;
+ }
+
/* Else find or make the PgStat_TableStatus entry, and update link */
- rel->pgstat_info = pgstat_prep_relation_pending(RelationGetRelid(rel),
- rel->rd_rel->relisshared);
+ rel->pgstat_info = pgstat_prep_relation_pending(locator);
/* don't allow link a stats to multiple relcache entries */
Assert(rel->pgstat_info->relation == NULL);
@@ -167,9 +197,13 @@ pgstat_unlink_relation(Relation rel)
void
pgstat_create_relation(Relation rel)
{
+ /* don't track stats for relations without storage */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+ return;
+
pgstat_create_transactional(PGSTAT_KIND_RELATION,
- rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
- RelationGetRelid(rel));
+ rel->rd_locator.dbOid,
+ RelFileLocatorToPgStatObjid(rel->rd_locator));
}
/*
@@ -181,9 +215,13 @@ pgstat_drop_relation(Relation rel)
int nest_level = GetCurrentTransactionNestLevel();
PgStat_TableStatus *pgstat_info;
+ /* don't track stats for relations without storage */
+ if (!RELKIND_HAS_STORAGE(rel->rd_rel->relkind))
+ return;
+
pgstat_drop_transactional(PGSTAT_KIND_RELATION,
- rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId,
- RelationGetRelid(rel));
+ rel->rd_locator.dbOid,
+ RelFileLocatorToPgStatObjid(rel->rd_locator));
if (!pgstat_should_count_relation(rel))
return;
@@ -213,20 +251,23 @@ pgstat_report_vacuum(Relation rel, PgStat_Counter livetuples,
PgStat_EntryRef *entry_ref;
PgStatShared_Relation *shtabentry;
PgStat_StatTabEntry *tabentry;
- Oid dboid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
TimestampTz ts;
PgStat_Counter elapsedtime;
+ RelFileLocator locator;
if (!pgstat_track_counts)
return;
+ locator = rel->rd_locator;
+
/* Store the data in the table's hash table entry. */
ts = GetCurrentTimestamp();
elapsedtime = TimestampDifferenceMilliseconds(starttime, ts);
/* block acquiring lock for the same reason as pgstat_report_autovac() */
- entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, dboid,
- RelationGetRelid(rel), false);
+ entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator),
+ false);
shtabentry = (PgStatShared_Relation *) entry_ref->shared_stats;
tabentry = &shtabentry->stats;
@@ -285,9 +326,9 @@ pgstat_report_analyze(Relation rel,
PgStat_EntryRef *entry_ref;
PgStatShared_Relation *shtabentry;
PgStat_StatTabEntry *tabentry;
- Oid dboid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
TimestampTz ts;
PgStat_Counter elapsedtime;
+ RelFileLocator locator;
if (!pgstat_track_counts)
return;
@@ -325,9 +366,25 @@ pgstat_report_analyze(Relation rel,
ts = GetCurrentTimestamp();
elapsedtime = TimestampDifferenceMilliseconds(starttime, ts);
+ if (rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE)
+ locator = rel->rd_locator;
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator.dbOid = (rel->rd_rel->relisshared ? InvalidOid : MyDatabaseId);
+ locator.spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator.relNumber = rel->rd_id;
+ }
/* block acquiring lock for the same reason as pgstat_report_autovac() */
- entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION, dboid,
- RelationGetRelid(rel),
+ entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator),
false);
/* can't get dropped while accessed */
Assert(entry_ref != NULL && entry_ref->shared_stats != NULL);
@@ -468,7 +525,16 @@ pgstat_update_heap_dead_tuples(Relation rel, int delta)
PgStat_StatTabEntry *
pgstat_fetch_stat_tabentry(Oid relid)
{
- return pgstat_fetch_stat_tabentry_ext(IsSharedRelation(relid), relid);
+ return pgstat_fetch_stat_tabentry_ext(relid);
+}
+
+PgStat_StatTabEntry *
+pgstat_fetch_stat_tabentry_by_locator(RelFileLocator locator)
+{
+ return (PgStat_StatTabEntry *) pgstat_fetch_entry(
+ PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
}
/*
@@ -476,12 +542,14 @@ pgstat_fetch_stat_tabentry(Oid relid)
* whether the to-be-accessed table is a shared relation or not.
*/
PgStat_StatTabEntry *
-pgstat_fetch_stat_tabentry_ext(bool shared, Oid reloid)
+pgstat_fetch_stat_tabentry_ext(Oid reloid)
{
- Oid dboid = (shared ? InvalidOid : MyDatabaseId);
+ RelFileLocator locator;
- return (PgStat_StatTabEntry *)
- pgstat_fetch_entry(PGSTAT_KIND_RELATION, dboid, reloid);
+ if (!pgstat_reloid_to_relfilelocator(reloid, &locator))
+ return NULL;
+
+ return pgstat_fetch_stat_tabentry_by_locator(locator);
}
/*
@@ -503,14 +571,17 @@ find_tabstat_entry(Oid rel_id)
PgStat_TableXactStatus *trans;
PgStat_TableStatus *tabentry = NULL;
PgStat_TableStatus *tablestatus = NULL;
+ RelFileLocator locator;
+
+ if (!pgstat_reloid_to_relfilelocator(rel_id, &locator))
+ return NULL;
+
+ entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION,
+ locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
- entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, MyDatabaseId, rel_id);
if (!entry_ref)
- {
- entry_ref = pgstat_fetch_pending_entry(PGSTAT_KIND_RELATION, InvalidOid, rel_id);
- if (!entry_ref)
- return tablestatus;
- }
+ return tablestatus;
tabentry = (PgStat_TableStatus *) entry_ref->pending;
tablestatus = palloc_object(PgStat_TableStatus);
@@ -706,8 +777,12 @@ AtPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state)
record.inserted_pre_truncdrop = trans->inserted_pre_truncdrop;
record.updated_pre_truncdrop = trans->updated_pre_truncdrop;
record.deleted_pre_truncdrop = trans->deleted_pre_truncdrop;
- record.id = tabstat->id;
- record.shared = tabstat->shared;
+
+ if (tabstat->relation != NULL)
+ record.locator = tabstat->relation->rd_locator;
+ else
+ record.locator = tabstat->locator;
+
record.truncdropped = trans->truncdropped;
RegisterTwoPhaseRecord(TWOPHASE_RM_PGSTAT_ID, 0,
@@ -750,7 +825,7 @@ pgstat_twophase_postcommit(FullTransactionId fxid, uint16 info,
PgStat_TableStatus *pgstat_info;
/* Find or create a tabstat entry for the rel */
- pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+ pgstat_info = pgstat_prep_relation_pending(rec->locator);
/* Same math as in AtEOXact_PgStat, commit case */
pgstat_info->counts.tuples_inserted += rec->tuples_inserted;
@@ -785,8 +860,8 @@ pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
TwoPhasePgStatRecord *rec = (TwoPhasePgStatRecord *) recdata;
PgStat_TableStatus *pgstat_info;
- /* Find or create a tabstat entry for the rel */
- pgstat_info = pgstat_prep_relation_pending(rec->id, rec->shared);
+ /* Find or create a tabstat entry for the target locator */
+ pgstat_info = pgstat_prep_relation_pending(rec->locator);
/* Same math as in AtEOXact_PgStat, abort case */
if (rec->truncdropped)
@@ -920,17 +995,21 @@ pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
* initialized if not exists.
*/
static PgStat_TableStatus *
-pgstat_prep_relation_pending(Oid rel_id, bool isshared)
+pgstat_prep_relation_pending(RelFileLocator locator)
{
PgStat_EntryRef *entry_ref;
PgStat_TableStatus *pending;
+ uint64 objid;
+
+ objid = RelFileLocatorToPgStatObjid(locator);
entry_ref = pgstat_prep_pending_entry(PGSTAT_KIND_RELATION,
- isshared ? InvalidOid : MyDatabaseId,
- rel_id, NULL);
+ locator.dbOid,
+ objid, NULL);
+
pending = entry_ref->pending;
- pending->id = rel_id;
- pending->shared = isshared;
+ pending->id = objid;
+ pending->locator = locator;
return pending;
}
@@ -1009,3 +1088,82 @@ restore_truncdrop_counters(PgStat_TableXactStatus *trans)
trans->tuples_deleted = trans->deleted_pre_truncdrop;
}
}
+
+/*
+ * Convert a relation OID to its corresponding RelFileLocator for statistics
+ * tracking purposes.
+ *
+ * Returns true on success, false if the relation doesn't need statistics
+ * tracking.
+ *
+ * For partitioned tables, constructs a synthetic locator using the relation
+ * OID as relNumber, since they don't have storage.
+ */
+bool
+pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator)
+{
+ HeapTuple tuple;
+ Form_pg_class relform;
+ bool result = true;
+
+ /* get the relation's tuple from pg_class */
+ tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(reloid));
+
+ if (!HeapTupleIsValid(tuple))
+ return false;
+
+ relform = (Form_pg_class) GETSTRUCT(tuple);
+
+ /* skip relations without storage and non partitioned tables */
+ if (!RELKIND_HAS_STORAGE(relform->relkind) &&
+ relform->relkind != RELKIND_PARTITIONED_TABLE)
+ {
+ ReleaseSysCache(tuple);
+ return false;
+ }
+
+ if (relform->relkind != RELKIND_PARTITIONED_TABLE)
+ {
+ /* build the RelFileLocator */
+ locator->relNumber = relform->relfilenode;
+ locator->spcOid = relform->reltablespace;
+
+ /* handle default tablespace */
+ if (!OidIsValid(locator->spcOid))
+ locator->spcOid = MyDatabaseTableSpace;
+
+ /* handle dbOid for global vs local relations */
+ if (locator->spcOid == GLOBALTABLESPACE_OID)
+ locator->dbOid = InvalidOid;
+ else
+ locator->dbOid = MyDatabaseId;
+
+ /* handle mapped relations */
+ if (!RelFileNumberIsValid(locator->relNumber))
+ {
+ locator->relNumber = RelationMapOidToFilenumber(reloid,
+ relform->relisshared);
+ if (!RelFileNumberIsValid(locator->relNumber))
+ {
+ ReleaseSysCache(tuple);
+ return false;
+ }
+ }
+ }
+ else
+ {
+ /*
+ * Partitioned tables don't have storage, so construct a synthetic
+ * locator for statistics tracking. Use a reserved pseudo tablespace
+ * OID that cannot conflict with real tablespaces, and the relation
+ * OID as relNumber. This ensures no collision with regular relations
+ * even after OID wraparound.
+ */
+ locator->dbOid = (relform->relisshared ? InvalidOid : MyDatabaseId);
+ locator->spcOid = PSEUDO_PARTITION_TABLE_SPCOID;
+ locator->relNumber = relform->oid;
+ }
+
+ ReleaseSysCache(tuple);
+ return result;
+}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 9185a8e6b83..db882339f1e 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -30,6 +30,7 @@
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/builtins.h"
+#include "utils/pgstat_internal.h"
#include "utils/timestamp.h"
#include "utils/tuplestore.h"
#include "utils/wait_event.h"
@@ -2004,9 +2005,14 @@ Datum
pg_stat_reset_single_table_counters(PG_FUNCTION_ARGS)
{
Oid taboid = PG_GETARG_OID(0);
- Oid dboid = (IsSharedRelation(taboid) ? InvalidOid : MyDatabaseId);
+ RelFileLocator locator;
- pgstat_reset(PGSTAT_KIND_RELATION, dboid, taboid);
+ /* Get the stats locator from the relation OID */
+ if (!pgstat_reloid_to_relfilelocator(taboid, &locator))
+ PG_RETURN_VOID();
+
+ pgstat_reset(PGSTAT_KIND_RELATION, locator.dbOid,
+ RelFileLocatorToPgStatObjid(locator));
PG_RETURN_VOID();
}
@@ -2363,5 +2369,16 @@ pg_stat_have_stats(PG_FUNCTION_ARGS)
uint64 objid = PG_GETARG_INT64(2);
PgStat_Kind kind = pgstat_get_kind_from_str(stats_type);
+ /* Convert relation OID to relfilenode objid */
+ if (kind == PGSTAT_KIND_RELATION)
+ {
+ RelFileLocator locator;
+
+ if (!pgstat_reloid_to_relfilelocator(objid, &locator))
+ PG_RETURN_BOOL(false);
+
+ objid = RelFileLocatorToPgStatObjid(locator);
+ }
+
PG_RETURN_BOOL(pgstat_have_entry(kind, dboid, objid));
}
diff --git a/src/include/catalog/pg_tablespace.dat b/src/include/catalog/pg_tablespace.dat
index c4cde415219..73ed046be31 100644
--- a/src/include/catalog/pg_tablespace.dat
+++ b/src/include/catalog/pg_tablespace.dat
@@ -10,6 +10,10 @@
#
#----------------------------------------------------------------------
+/*
+ * When adding a new one, ensure it does not conflict with
+ * PSEUDO_PARTITION_TABLE_SPCOID.
+ */
[
{ oid => '1663', oid_symbol => 'DEFAULTTABLESPACE_OID',
diff --git a/src/include/catalog/pg_tablespace.h b/src/include/catalog/pg_tablespace.h
index 3bd4a74f003..e5e818eb0c5 100644
--- a/src/include/catalog/pg_tablespace.h
+++ b/src/include/catalog/pg_tablespace.h
@@ -21,6 +21,14 @@
#include "catalog/genbki.h"
#include "catalog/pg_tablespace_d.h" /* IWYU pragma: export */
+/*
+ * Reserved tablespace OID for partitioned table pseudo locators.
+ * This is not an actual tablespace, just a reserved value to distinguish
+ * partitioned table statistics from regular table statistics. Ensures it does
+ * not conflict with the ones in pg_tablespace.dat.
+ */
+#define PSEUDO_PARTITION_TABLE_SPCOID 1665
+
/* ----------------
* pg_tablespace definition. cpp turns this into
* typedef struct FormData_pg_tablespace
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8e3549c3752..ef740aff26e 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -16,6 +16,7 @@
#include "postmaster/pgarch.h" /* for MAX_XFN_CHARS */
#include "replication/conflict.h"
#include "storage/locktag.h"
+#include "storage/relfilelocator.h"
#include "utils/backend_progress.h" /* for backward compatibility */ /* IWYU pragma: export */
#include "utils/backend_status.h" /* for backward compatibility */ /* IWYU pragma: export */
#include "utils/pgstat_kind.h"
@@ -39,6 +40,12 @@ typedef struct RelationData *Relation;
/* Default directory to store temporary statistics data in */
#define PG_STAT_TMP_DIR "pg_stat_tmp"
+/*
+ * Build a pgstat key Objid based on a RelFileLocator.
+ */
+#define RelFileLocatorToPgStatObjid(locator) \
+ (((uint64) (locator).spcOid << 32) | (locator).relNumber)
+
/* Values for track_functions GUC variable --- order is significant! */
typedef enum TrackFunctionsLevel
{
@@ -179,11 +186,11 @@ typedef struct PgStat_TableCounts
*/
typedef struct PgStat_TableStatus
{
- Oid id; /* table's OID */
- bool shared; /* is it a shared catalog? */
+ uint64 id; /* hash of relfilelocator for stats key */
struct PgStat_TableXactStatus *trans; /* lowest subxact's counts */
PgStat_TableCounts counts; /* event counts to be sent */
Relation relation; /* rel that is using this entry */
+ RelFileLocator locator; /* table's relfilelocator */
} PgStat_TableStatus;
/* ----------
@@ -766,8 +773,8 @@ extern void pgstat_twophase_postabort(FullTransactionId fxid, uint16 info,
void *recdata, uint32 len);
extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
-extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(bool shared,
- Oid reloid);
+extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_by_locator(RelFileLocator locator);
+extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry_ext(Oid reloid);
extern PgStat_TableStatus *find_tabstat_entry(Oid rel_id);
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index eed4c6b359c..1090f049058 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -786,6 +786,7 @@ extern void PostPrepare_PgStat_Relations(PgStat_SubXactStatus *xact_state);
extern bool pgstat_relation_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
extern void pgstat_relation_delete_pending_cb(PgStat_EntryRef *entry_ref);
extern void pgstat_relation_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts);
+extern bool pgstat_reloid_to_relfilelocator(Oid reloid, RelFileLocator *locator);
/*
diff --git a/src/test/recovery/t/029_stats_restart.pl b/src/test/recovery/t/029_stats_restart.pl
index cdc427dbc78..4d00087dc6f 100644
--- a/src/test/recovery/t/029_stats_restart.pl
+++ b/src/test/recovery/t/029_stats_restart.pl
@@ -55,10 +55,10 @@ trigger_funcrel_stat();
# verify stats objects exist
$sect = "initial";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
# regular shutdown
@@ -79,10 +79,10 @@ copy($og_stats, $statsfile) or die "Copy failed: $!";
$node->start;
$sect = "copy";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
$node->stop('immediate');
@@ -96,10 +96,10 @@ $node->start;
# stats should have been discarded
$sect = "post immediate";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
# get rid of backup statsfile
@@ -110,10 +110,10 @@ unlink $statsfile or die "cannot unlink $statsfile $!";
trigger_funcrel_stat();
$sect = "post immediate, new";
-is(have_stats('database', $dboid, 0), 't', "$sect: db stats do exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 't', "$sect: db stats do exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
't', "$sect: function stats do exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
't', "$sect: relation stats do exist");
# regular shutdown
@@ -129,10 +129,10 @@ $node->start;
# no stats present due to invalid stats file
$sect = "invalid_overwrite";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
@@ -145,10 +145,10 @@ append_file($og_stats, "XYZ");
$node->start;
$sect = "invalid_append";
-is(have_stats('database', $dboid, 0), 'f', "$sect: db stats do not exist");
-is(have_stats('function', $dboid, $funcoid),
+is(have_stats($connect_db, 'database', $dboid, 0), 'f', "$sect: db stats do not exist");
+is(have_stats($db_under_test, 'function', $dboid, $funcoid),
'f', "$sect: function stats do not exist");
-is(have_stats('relation', $dboid, $tableoid),
+is(have_stats($db_under_test, 'relation', $dboid, $tableoid),
'f', "$sect: relation stats do not exist");
@@ -307,9 +307,9 @@ sub trigger_funcrel_stat
sub have_stats
{
- my ($kind, $dboid, $objid) = @_;
+ my ($db, $kind, $dboid, $objid) = @_;
- return $node->safe_psql($connect_db,
+ return $node->safe_psql($db,
"SELECT pg_stat_have_stats('$kind', $dboid, $objid)");
}
--
2.34.1
--Og8T0Lf2JVsuKOzn
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v15-0002-handle-relation-statistics-correctly-during-rewr.patch"
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2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v4 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-08-09 14:22 [PATCH v5 3/3] Adding the pg_stat_backend_transaction view Bertrand Drouvot <[email protected]>
2025-10-01 09:45 [PATCH v15 1/2] Key PGSTAT_KIND_RELATION by relfile locator Bertrand Drouvot <[email protected]>
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