Add a txn_start column to pg_stat_activity. This makes it easier to

identify long-running transactions. Since we already need to record
the transaction-start time (e.g. for now()), we don't need any
additional system calls to report this information.

Catversion bumped, initdb required.

doc/src/sgml/monitoring.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.41 2006/12/02 09:29:51 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/monitoring.sgml,v 1.42 2006/12/06 18:06:46 neilc Exp $ -->
 
 <chapter id="monitoring">
  <title>Monitoring Database Activity</title>
@@ -244,16 +244,16 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
     <tbody>
      <row>
       <entry><structname>pg_stat_activity</></entry>
-      <entry>One row per server process, showing database OID, database name,
-      process <acronym>ID</>, user OID, user name, current query, query's
-      waiting status, time at
-      which the current query began execution, time at which the process
-      was started, and client's address and port number.  The columns
-      that report data on the current query are available unless the
-      parameter <varname>stats_command_string</varname> has been
-      turned off.  Furthermore, these columns are only visible if the
-      user examining the view is a superuser or the same as the user
-      owning the process being reported on.
+      <entry>One row per server process, showing database OID, database
+      name, process <acronym>ID</>, user OID, user name, current query,
+      query's waiting status, time at which the current transaction and
+      current query began execution, time at which the process was
+      started, and client's address and port number.  The columns that
+      report data on the current query are available unless the parameter
+      <varname>stats_command_string</varname> has been turned off.
+      Furthermore, these columns are only visible if the user examining
+      the view is a superuser or the same as the user owning the process
+      being reported on.
      </entry>
      </row>
 

src/backend/access/transam/xact.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.229 2006/11/23 01:14:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.230 2006/12/06 18:06:47 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1416,6 +1416,7 @@ StartTransaction(void)
 	 * GetCurrentTimestamp() call (which'd be expensive anyway).
 	 */
 	xactStartTimestamp = stmtStartTimestamp;
+	pgstat_report_txn_timestamp(xactStartTimestamp);
 
 	/*
 	 * initialize current transaction state fields
@@ -1628,6 +1629,7 @@ CommitTransaction(void)
 	/* smgrcommit already done */
 	AtEOXact_Files();
 	pgstat_count_xact_commit();
+	pgstat_report_txn_timestamp(0);
 
 	CurrentResourceOwner = NULL;
 	ResourceOwnerDelete(TopTransactionResourceOwner);
@@ -1994,6 +1996,7 @@ AbortTransaction(void)
 	smgrabort();
 	AtEOXact_Files();
 	pgstat_count_xact_rollback();
+	pgstat_report_txn_timestamp(0);
 
 	/*
 	 * State remains TRANS_ABORT until CleanupTransaction().

src/backend/catalog/system_views.sql

@@ -3,7 +3,7 @@
  *
  * Copyright (c) 1996-2006, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.32 2006/11/24 21:18:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/system_views.sql,v 1.33 2006/12/06 18:06:47 neilc Exp $
  */
 
 CREATE VIEW pg_roles AS 
@@ -335,6 +335,7 @@ CREATE VIEW pg_stat_activity AS
             U.rolname AS usename, 
             pg_stat_get_backend_activity(S.backendid) AS current_query,
             pg_stat_get_backend_waiting(S.backendid) AS waiting,
+            pg_stat_get_backend_txn_start(S.backendid) AS txn_start,
             pg_stat_get_backend_activity_start(S.backendid) AS query_start,
             pg_stat_get_backend_start(S.backendid) AS backend_start,
             pg_stat_get_backend_client_addr(S.backendid) AS client_addr,

src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2006, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.140 2006/11/21 20:59:52 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.141 2006/12/06 18:06:47 neilc Exp $
  * ----------
  */
 #include "postgres.h"
@@ -1355,6 +1355,7 @@ pgstat_bestart(void)
 	beentry->st_procpid = MyProcPid;
 	beentry->st_proc_start_timestamp = proc_start_timestamp;
 	beentry->st_activity_start_timestamp = 0;
+	beentry->st_txn_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
 	beentry->st_userid = userid;
 	beentry->st_clientaddr = clientaddr;
@@ -1443,6 +1444,29 @@ pgstat_report_activity(const char *cmd_str)
 	Assert((beentry->st_changecount & 1) == 0);
 }
 
+/*
+ * Set the current transaction start timestamp to the specified
+ * value. If there is no current active transaction, this is signified
+ * by 0.
+ */
+void
+pgstat_report_txn_timestamp(TimestampTz tstamp)
+{
+	volatile PgBackendStatus *beentry = MyBEEntry;
+
+	if (!pgstat_collect_querystring || !beentry)
+		return;
+
+	/*
+	 * Update my status entry, following the protocol of bumping
+	 * st_changecount before and after.  We use a volatile pointer
+	 * here to ensure the compiler doesn't try to get cute.
+	 */
+	beentry->st_changecount++;
+	beentry->st_txn_start_timestamp = tstamp;
+	beentry->st_changecount++;
+	Assert((beentry->st_changecount & 1) == 0);
+}
 
 /* ----------
  * pgstat_report_waiting() -

src/backend/utils/adt/pgstatfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.34 2006/10/04 00:29:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/pgstatfuncs.c,v 1.35 2006/12/06 18:06:47 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -44,6 +44,7 @@ extern Datum pg_stat_get_backend_userid(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_activity(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_waiting(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_activity_start(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_backend_txn_start(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_start(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_client_addr(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_backend_client_port(PG_FUNCTION_ARGS);
@@ -422,6 +423,29 @@ pg_stat_get_backend_activity_start(PG_FUNCTION_ARGS)
 	PG_RETURN_TIMESTAMPTZ(result);
 }
 
+
+Datum
+pg_stat_get_backend_txn_start(PG_FUNCTION_ARGS)
+{
+	int32		beid = PG_GETARG_INT32(0);
+	TimestampTz result;
+	PgBackendStatus *beentry;
+
+	if ((beentry = pgstat_fetch_stat_beentry(beid)) == NULL)
+		PG_RETURN_NULL();
+
+	if (!superuser() && beentry->st_userid != GetUserId())
+		PG_RETURN_NULL();
+
+	result = beentry->st_txn_start_timestamp;
+
+	if (result == 0)			/* not in a transaction */
+		PG_RETURN_NULL();
+
+	PG_RETURN_TIMESTAMPTZ(result);
+}
+
+
 Datum
 pg_stat_get_backend_start(PG_FUNCTION_ARGS)
 {

src/include/catalog/catversion.h

@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.360 2006/11/24 21:18:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.361 2006/12/06 18:06:47 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200611241
+#define CATALOG_VERSION_NO	200612061
 
 #endif

src/include/catalog/pg_proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.429 2006/11/28 19:18:44 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.430 2006/12/06 18:06:47 neilc Exp $
  *
  * NOTES
  *	  The script catalog/genbki.sh reads this file and generates .bki
@@ -2902,6 +2902,8 @@ DATA(insert OID = 2853 (  pg_stat_get_backend_waiting	PGNSP PGUID 12 f f t f s 1
 DESCR("Statistics: Is backend currently waiting for a lock");
 DATA(insert OID = 2094 (  pg_stat_get_backend_activity_start PGNSP PGUID 12 f f t f s 1 1184 "23" _null_ _null_ _null_	pg_stat_get_backend_activity_start - _null_));
 DESCR("Statistics: Start time for current query of backend");
+DATA(insert OID = 2857 (  pg_stat_get_backend_txn_start PGNSP PGUID 12 f f t f s 1 1184 "23" _null_ _null_ _null_	pg_stat_get_backend_txn_start - _null_));
+DESCR("Statistics: Start time for backend's current transaction");
 DATA(insert OID = 1391 ( pg_stat_get_backend_start PGNSP PGUID 12 f f t f s 1 1184 "23" _null_ _null_ _null_ pg_stat_get_backend_start - _null_));
 DESCR("Statistics: Start time for current backend session");
 DATA(insert OID = 1392 ( pg_stat_get_backend_client_addr PGNSP PGUID 12 f f t f s 1 869 "23" _null_ _null_ _null_ pg_stat_get_backend_client_addr - _null_));

src/include/pgstat.h

@@ -5,7 +5,7 @@
  *
  *	Copyright (c) 2001-2006, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.50 2006/10/04 00:30:06 momjian Exp $
+ *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.51 2006/12/06 18:06:47 neilc Exp $
  * ----------
  */
 #ifndef PGSTAT_H
@@ -325,8 +325,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
-	/* Times of backend process start and current activity start */
+	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
+	TimestampTz st_txn_start_timestamp;
 	TimestampTz st_activity_start_timestamp;
 
 	/* Database OID, owning user's OID, connection client address */
@@ -390,6 +391,7 @@ extern void pgstat_report_analyze(Oid tableoid, bool shared,
 
 extern void pgstat_bestart(void);
 extern void pgstat_report_activity(const char *what);
+extern void pgstat_report_txn_timestamp(TimestampTz tstamp);
 extern void pgstat_report_waiting(bool waiting);
 
 extern void pgstat_initstats(PgStat_Info *stats, Relation rel);

src/test/regress/expected/rules.out

@@ -1287,7 +1287,7 @@ SELECT viewname, definition FROM pg_views WHERE schemaname <> 'information_schem
  pg_rules                 | SELECT n.nspname AS schemaname, c.relname AS tablename, r.rulename, pg_get_ruledef(r.oid) AS definition FROM ((pg_rewrite r JOIN pg_class c ON ((c.oid = r.ev_class))) LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace))) WHERE (r.rulename <> '_RETURN'::name);
  pg_settings              | SELECT a.name, a.setting, a.unit, a.category, a.short_desc, a.extra_desc, a.context, a.vartype, a.source, a.min_val, a.max_val FROM pg_show_all_settings() a(name text, setting text, unit text, category text, short_desc text, extra_desc text, context text, vartype text, source text, min_val text, max_val text);
  pg_shadow                | SELECT pg_authid.rolname AS usename, pg_authid.oid AS usesysid, pg_authid.rolcreatedb AS usecreatedb, pg_authid.rolsuper AS usesuper, pg_authid.rolcatupdate AS usecatupd, pg_authid.rolpassword AS passwd, (pg_authid.rolvaliduntil)::abstime AS valuntil, pg_authid.rolconfig AS useconfig FROM pg_authid WHERE pg_authid.rolcanlogin;
- pg_stat_activity         | SELECT d.oid AS datid, d.datname, pg_stat_get_backend_pid(s.backendid) AS procpid, pg_stat_get_backend_userid(s.backendid) AS usesysid, u.rolname AS usename, pg_stat_get_backend_activity(s.backendid) AS current_query, pg_stat_get_backend_waiting(s.backendid) AS waiting, pg_stat_get_backend_activity_start(s.backendid) AS query_start, pg_stat_get_backend_start(s.backendid) AS backend_start, pg_stat_get_backend_client_addr(s.backendid) AS client_addr, pg_stat_get_backend_client_port(s.backendid) AS client_port FROM pg_database d, (SELECT pg_stat_get_backend_idset() AS backendid) s, pg_authid u WHERE ((pg_stat_get_backend_dbid(s.backendid) = d.oid) AND (pg_stat_get_backend_userid(s.backendid) = u.oid));
+ pg_stat_activity         | SELECT d.oid AS datid, d.datname, pg_stat_get_backend_pid(s.backendid) AS procpid, pg_stat_get_backend_userid(s.backendid) AS usesysid, u.rolname AS usename, pg_stat_get_backend_activity(s.backendid) AS current_query, pg_stat_get_backend_waiting(s.backendid) AS waiting, pg_stat_get_backend_txn_start(s.backendid) AS txn_start, pg_stat_get_backend_activity_start(s.backendid) AS query_start, pg_stat_get_backend_start(s.backendid) AS backend_start, pg_stat_get_backend_client_addr(s.backendid) AS client_addr, pg_stat_get_backend_client_port(s.backendid) AS client_port FROM pg_database d, (SELECT pg_stat_get_backend_idset() AS backendid) s, pg_authid u WHERE ((pg_stat_get_backend_dbid(s.backendid) = d.oid) AND (pg_stat_get_backend_userid(s.backendid) = u.oid));
  pg_stat_all_indexes      | SELECT c.oid AS relid, i.oid AS indexrelid, n.nspname AS schemaname, c.relname, i.relname AS indexrelname, pg_stat_get_numscans(i.oid) AS idx_scan, pg_stat_get_tuples_returned(i.oid) AS idx_tup_read, pg_stat_get_tuples_fetched(i.oid) AS idx_tup_fetch FROM (((pg_class c JOIN pg_index x ON ((c.oid = x.indrelid))) JOIN pg_class i ON ((i.oid = x.indexrelid))) LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace))) WHERE (c.relkind = ANY (ARRAY['r'::"char", 't'::"char"]));
  pg_stat_all_tables       | SELECT c.oid AS relid, n.nspname AS schemaname, c.relname, pg_stat_get_numscans(c.oid) AS seq_scan, pg_stat_get_tuples_returned(c.oid) AS seq_tup_read, (sum(pg_stat_get_numscans(i.indexrelid)))::bigint AS idx_scan, ((sum(pg_stat_get_tuples_fetched(i.indexrelid)))::bigint + pg_stat_get_tuples_fetched(c.oid)) AS idx_tup_fetch, pg_stat_get_tuples_inserted(c.oid) AS n_tup_ins, pg_stat_get_tuples_updated(c.oid) AS n_tup_upd, pg_stat_get_tuples_deleted(c.oid) AS n_tup_del, pg_stat_get_last_vacuum_time(c.oid) AS last_vacuum, pg_stat_get_last_autovacuum_time(c.oid) AS last_autovacuum, pg_stat_get_last_analyze_time(c.oid) AS last_analyze, pg_stat_get_last_autoanalyze_time(c.oid) AS last_autoanalyze FROM ((pg_class c LEFT JOIN pg_index i ON ((c.oid = i.indrelid))) LEFT JOIN pg_namespace n ON ((n.oid = c.relnamespace))) WHERE (c.relkind = ANY (ARRAY['r'::"char", 't'::"char"])) GROUP BY c.oid, n.nspname, c.relname;
  pg_stat_database         | SELECT d.oid AS datid, d.datname, pg_stat_get_db_numbackends(d.oid) AS numbackends, pg_stat_get_db_xact_commit(d.oid) AS xact_commit, pg_stat_get_db_xact_rollback(d.oid) AS xact_rollback, (pg_stat_get_db_blocks_fetched(d.oid) - pg_stat_get_db_blocks_hit(d.oid)) AS blks_read, pg_stat_get_db_blocks_hit(d.oid) AS blks_hit FROM pg_database d;