Add views and functions to monitor hot standby query conflicts

Add the view pg_stat_database_conflicts and a column to pg_stat_database,
and the underlying functions to provide the information.

doc/src/sgml/high-availability.sgml

@@ -1554,6 +1554,13 @@ if (!triggered)
     approach, since <varname>vacuum_defer_cleanup_age</> is measured in
     transactions executed on the primary server.
    </para>
+
+   <para>
+    The number of query cancels and the reason for them can be viewed using
+    the <structname>pg_stat_database_conflicts</> system view on the standby
+    server. The <structname>pg_stat_database</> system view also contains
+    summary information.
+   </para>
   </sect2>
 
   <sect2 id="hot-standby-admin">

doc/src/sgml/monitoring.sgml

@@ -278,7 +278,19 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
       number of transactions committed and rolled back in that database,
       total disk blocks read, total buffer hits (i.e., block
       read requests avoided by finding the block already in buffer cache),
-      number of rows returned, fetched, inserted, updated and deleted.
+      number of rows returned, fetched, inserted, updated and deleted, and
+      total number of queries cancelled due to conflict with recovery (on
+      standby servers).
+     </entry>
+     </row>
+
+     <row>
+      <entry><structname>pg_stat_database_conflicts</><indexterm><primary>pg_stat_database_conflicts</primary></indexterm></entry>
+      <entry>One row per database, showing database OID, database name and
+      the number of queries that have been cancelled in this database due to
+      dropped tablespaces, lock timeouts, old snapshots, pinned buffers and
+      deadlocks. Will only contain information on standby servers, since
+      conflicts do not occur on master servers.
      </entry>
      </row>
 
@@ -599,6 +611,46 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
       </entry>
      </row>
 
+     <row>
+      <entry><literal><function>pg_stat_get_db_conflict_tablespace</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of queries cancelled because of recovery conflict with dropped tablespaces in database
+      </entry>
+     </row>
+
+     <row>
+      <entry><literal><function>pg_stat_get_db_conflict_lock</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of queries cancelled because of recovery conflict with locks in database
+      </entry>
+     </row>
+
+     <row>
+      <entry><literal><function>pg_stat_get_db_conflict_snapshot</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of queries cancelled because of recovery conflict with old snapshots in database
+      </entry>
+     </row>
+
+     <row>
+      <entry><literal><function>pg_stat_get_db_conflict_bufferpin</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of queries cancelled because of recovery conflict with pinned buffers in database
+      </entry>
+     </row>
+
+     <row>
+      <entry><literal><function>pg_stat_get_db_conflict_startup_deadlock</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of queries cancelled because of recovery conflict with deadlocks in database
+      </entry>
+     </row>
+
      <row>
       <entry><literal><function>pg_stat_get_numscans</function>(<type>oid</type>)</literal></entry>
       <entry><type>bigint</type></entry>

src/backend/catalog/system_views.sql

@@ -506,7 +506,19 @@ CREATE VIEW pg_stat_database AS
             pg_stat_get_db_tuples_fetched(D.oid) AS tup_fetched,
             pg_stat_get_db_tuples_inserted(D.oid) AS tup_inserted,
             pg_stat_get_db_tuples_updated(D.oid) AS tup_updated,
-            pg_stat_get_db_tuples_deleted(D.oid) AS tup_deleted
+            pg_stat_get_db_tuples_deleted(D.oid) AS tup_deleted,
+            pg_stat_get_db_conflict_all(D.oid) AS conflicts
+    FROM pg_database D;
+
+CREATE VIEW pg_stat_database_conflicts AS
+    SELECT
+            D.oid AS datid,
+            D.datname AS datname,
+            pg_stat_get_db_conflict_tablespace(D.oid) AS confl_tablespace,
+            pg_stat_get_db_conflict_lock(D.oid) AS confl_lock,
+            pg_stat_get_db_conflict_snapshot(D.oid) AS confl_snapshot,
+            pg_stat_get_db_conflict_bufferpin(D.oid) AS confl_bufferpin,
+            pg_stat_get_db_conflict_startup_deadlock(D.oid) AS confl_deadlock
     FROM pg_database D;
 
 CREATE VIEW pg_stat_user_functions AS

src/backend/postmaster/pgstat.c

@@ -57,6 +57,7 @@
 #include "storage/ipc.h"
 #include "storage/pg_shmem.h"
 #include "storage/pmsignal.h"
+#include "storage/procsignal.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/ps_status.h"
@@ -278,6 +279,7 @@ static void pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len);
 static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len);
 static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len);
 static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len);
+static void pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len);
 
 
 /* ------------------------------------------------------------
@@ -1314,6 +1316,25 @@ pgstat_report_analyze(Relation rel, bool adopt_counts,
 	pgstat_send(&msg, sizeof(msg));
 }
 
+/* --------
+ * pgstat_report_recovery_conflict() -
+ *
+ *  Tell the collector about a Hot Standby recovery conflict.
+ * --------
+ */
+void
+pgstat_report_recovery_conflict(int reason)
+{
+	PgStat_MsgRecoveryConflict msg;
+
+	if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
+		return;
+
+	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RECOVERYCONFLICT);
+	msg.m_databaseid = MyDatabaseId;
+	msg.m_reason = reason;
+	pgstat_send(&msg, sizeof(msg));
+}
 
 /* ----------
  * pgstat_ping() -
@@ -3053,6 +3074,10 @@ PgstatCollectorMain(int argc, char *argv[])
 					pgstat_recv_funcpurge((PgStat_MsgFuncpurge *) &msg, len);
 					break;
 
+				case PGSTAT_MTYPE_RECOVERYCONFLICT:
+					pgstat_recv_recoveryconflict((PgStat_MsgRecoveryConflict *) &msg, len);
+					break;
+
 				default:
 					break;
 			}
@@ -3129,6 +3154,11 @@ pgstat_get_db_entry(Oid databaseid, bool create)
 		result->n_tuples_updated = 0;
 		result->n_tuples_deleted = 0;
 		result->last_autovac_time = 0;
+		result->n_conflict_tablespace = 0;
+		result->n_conflict_lock = 0;
+		result->n_conflict_snapshot = 0;
+		result->n_conflict_bufferpin = 0;
+		result->n_conflict_startup_deadlock = 0;
 
 		memset(&hash_ctl, 0, sizeof(hash_ctl));
 		hash_ctl.keysize = sizeof(Oid);
@@ -4203,6 +4233,45 @@ pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len)
 	globalStats.buf_alloc += msg->m_buf_alloc;
 }
 
+/* ----------
+ * pgstat_recv_recoveryconflict() -
+ *
+ *  Process as RECOVERYCONFLICT message.
+ * ----------
+ */
+static void
+pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len)
+{
+	PgStat_StatDBEntry *dbentry;
+	dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
+
+	switch (msg->m_reason)
+	{
+		case PROCSIG_RECOVERY_CONFLICT_DATABASE:
+			/*
+			 * Since we drop the information about the database as soon
+			 * as it replicates, there is no point in counting these
+			 * conflicts.
+			 */
+			break;
+		case PROCSIG_RECOVERY_CONFLICT_TABLESPACE:
+			dbentry->n_conflict_tablespace++;
+			break;
+		case PROCSIG_RECOVERY_CONFLICT_LOCK:
+			dbentry->n_conflict_lock++;
+			break;
+		case PROCSIG_RECOVERY_CONFLICT_SNAPSHOT:
+			dbentry->n_conflict_snapshot++;
+			break;
+		case PROCSIG_RECOVERY_CONFLICT_BUFFERPIN:
+			dbentry->n_conflict_bufferpin++;
+			break;
+		case PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK:
+			dbentry->n_conflict_startup_deadlock++;
+			break;
+	}
+}
+
 /* ----------
  * pgstat_recv_funcstat() -
  *

src/backend/tcop/postgres.c

@@ -2903,15 +2903,21 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_ADMIN_SHUTDOWN),
 					 errmsg("terminating autovacuum process due to administrator command")));
 		else if (RecoveryConflictPending && RecoveryConflictRetryable)
+		{
+			pgstat_report_recovery_conflict(RecoveryConflictReason);
 			ereport(FATAL,
 					(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
 			  errmsg("terminating connection due to conflict with recovery"),
 					 errdetail_recovery_conflict()));
+		}
 		else if (RecoveryConflictPending)
+		{
+			pgstat_report_recovery_conflict(RecoveryConflictReason);
 			ereport(FATAL,
 					(errcode(ERRCODE_ADMIN_SHUTDOWN),
 			  errmsg("terminating connection due to conflict with recovery"),
 					 errdetail_recovery_conflict()));
+		}
 		else
 			ereport(FATAL,
 					(errcode(ERRCODE_ADMIN_SHUTDOWN),
@@ -2956,6 +2962,7 @@ ProcessInterrupts(void)
 			RecoveryConflictPending = false;
 			DisableNotifyInterrupt();
 			DisableCatchupInterrupt();
+			pgstat_report_recovery_conflict(RecoveryConflictReason);
 			if (DoingCommandRead)
 				ereport(FATAL,
 						(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),

src/backend/utils/adt/pgstatfuncs.c

@@ -71,6 +71,12 @@ extern Datum pg_stat_get_db_tuples_fetched(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_tuples_inserted(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_tuples_updated(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_tablespace(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_lock(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_snapshot(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_bufferpin(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_startup_deadlock(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_db_conflict_all(PG_FUNCTION_ARGS);
 
 extern Datum pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_bgwriter_requested_checkpoints(PG_FUNCTION_ARGS);
@@ -1129,6 +1135,101 @@ pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(result);
 }
 
+Datum
+pg_stat_get_db_conflict_tablespace(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_conflict_tablespace);
+
+	PG_RETURN_INT64(result);
+}
+
+Datum
+pg_stat_get_db_conflict_lock(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_conflict_lock);
+
+	PG_RETURN_INT64(result);
+}
+
+Datum
+pg_stat_get_db_conflict_snapshot(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_conflict_snapshot);
+
+	PG_RETURN_INT64(result);
+}
+
+Datum
+pg_stat_get_db_conflict_bufferpin(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_conflict_bufferpin);
+
+	PG_RETURN_INT64(result);
+}
+
+Datum
+pg_stat_get_db_conflict_startup_deadlock(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (dbentry->n_conflict_startup_deadlock);
+
+	PG_RETURN_INT64(result);
+}
+
+Datum
+pg_stat_get_db_conflict_all(PG_FUNCTION_ARGS)
+{
+	Oid			dbid = PG_GETARG_OID(0);
+	int64		result;
+	PgStat_StatDBEntry *dbentry;
+
+	if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+		result = 0;
+	else
+		result = (int64) (
+			dbentry->n_conflict_tablespace +
+			dbentry->n_conflict_lock +
+			dbentry->n_conflict_snapshot +
+			dbentry->n_conflict_bufferpin +
+			dbentry->n_conflict_startup_deadlock);
+
+	PG_RETURN_INT64(result);
+}
+
 Datum
 pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS)
 {

src/include/catalog/pg_proc.h

@@ -3117,6 +3117,18 @@ DATA(insert OID = 2761 (  pg_stat_get_db_tuples_updated PGNSP PGUID 12 1 0 0 f f
 DESCR("statistics: tuples updated in database");
 DATA(insert OID = 2762 (  pg_stat_get_db_tuples_deleted PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_tuples_deleted _null_ _null_ _null_ ));
 DESCR("statistics: tuples deleted in database");
+DATA(insert OID = 3065 (  pg_stat_get_db_conflict_tablespace PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_tablespace _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database caused by drop tablespace");
+DATA(insert OID = 3066 (  pg_stat_get_db_conflict_lock PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_lock _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database caused by relation lock");
+DATA(insert OID = 3067 (  pg_stat_get_db_conflict_snapshot PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_snapshot _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database caused by snapshot expiry");
+DATA(insert OID = 3068 (  pg_stat_get_db_conflict_bufferpin PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_bufferpin _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database caused by shared buffer pin");
+DATA(insert OID = 3069 (  pg_stat_get_db_conflict_startup_deadlock PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_startup_deadlock _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database caused by buffer deadlock");
+DATA(insert OID = 3070 (  pg_stat_get_db_conflict_all PGNSP PGUID 12 1 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_conflict_all _null_ _null_ _null_ ));
+DESCR("statistics: recovery conflicts in database");
 DATA(insert OID = 2769 ( pg_stat_get_bgwriter_timed_checkpoints PGNSP PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_bgwriter_timed_checkpoints _null_ _null_ _null_ ));
 DESCR("statistics: number of timed checkpoints started by the bgwriter");
 DATA(insert OID = 2770 ( pg_stat_get_bgwriter_requested_checkpoints PGNSP PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_bgwriter_requested_checkpoints _null_ _null_ _null_ ));

src/include/pgstat.h

@@ -45,7 +45,8 @@ typedef enum StatMsgType
 	PGSTAT_MTYPE_ANALYZE,
 	PGSTAT_MTYPE_BGWRITER,
 	PGSTAT_MTYPE_FUNCSTAT,
-	PGSTAT_MTYPE_FUNCPURGE
+	PGSTAT_MTYPE_FUNCPURGE,
+	PGSTAT_MTYPE_RECOVERYCONFLICT
 } StatMsgType;
 
 /* ----------
@@ -364,6 +365,17 @@ typedef struct PgStat_MsgBgWriter
 	PgStat_Counter m_buf_alloc;
 } PgStat_MsgBgWriter;
 
+/* ----------
+ * PgStat_MsgRecoveryConflict	Sent by the backend upon recovery conflict
+ * ----------
+ */
+typedef struct PgStat_MsgRecoveryConflict
+{
+	PgStat_MsgHdr m_hdr;
+
+	Oid			m_databaseid;
+	int			m_reason;
+} PgStat_MsgRecoveryConflict;
 
 /* ----------
  * PgStat_FunctionCounts	The actual per-function counts kept by a backend
@@ -460,6 +472,7 @@ typedef union PgStat_Msg
 	PgStat_MsgBgWriter msg_bgwriter;
 	PgStat_MsgFuncstat msg_funcstat;
 	PgStat_MsgFuncpurge msg_funcpurge;
+	PgStat_MsgRecoveryConflict msg_recoveryconflict;
 } PgStat_Msg;
 
 
@@ -490,6 +503,12 @@ typedef struct PgStat_StatDBEntry
 	PgStat_Counter n_tuples_updated;
 	PgStat_Counter n_tuples_deleted;
 	TimestampTz last_autovac_time;
+	PgStat_Counter n_conflict_tablespace;
+	PgStat_Counter n_conflict_lock;
+	PgStat_Counter n_conflict_snapshot;
+	PgStat_Counter n_conflict_bufferpin;
+	PgStat_Counter n_conflict_startup_deadlock;
+
 
 	/*
 	 * tables and functions must be last in the struct, because we don't write
@@ -689,6 +708,8 @@ extern void pgstat_report_vacuum(Oid tableoid, bool shared, bool adopt_counts,
 extern void pgstat_report_analyze(Relation rel, bool adopt_counts,
 					  PgStat_Counter livetuples, PgStat_Counter deadtuples);
 
+extern void pgstat_report_recovery_conflict(int reason);
+
 extern void pgstat_initialize(void);
 extern void pgstat_bestart(void);
 

src/test/regress/expected/rules.out

@@ -1294,7 +1294,8 @@ SELECT viewname, definition FROM pg_views WHERE schemaname <> 'information_schem
  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_tuples_hot_updated(c.oid) AS n_tup_hot_upd, pg_stat_get_live_tuples(c.oid) AS n_live_tup, pg_stat_get_dead_tuples(c.oid) AS n_dead_tup, 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, pg_stat_get_vacuum_count(c.oid) AS vacuum_count, pg_stat_get_autovacuum_count(c.oid) AS autovacuum_count, pg_stat_get_analyze_count(c.oid) AS analyze_count, pg_stat_get_autoanalyze_count(c.oid) AS autoanalyze_count 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_bgwriter            | SELECT pg_stat_get_bgwriter_timed_checkpoints() AS checkpoints_timed, pg_stat_get_bgwriter_requested_checkpoints() AS checkpoints_req, pg_stat_get_bgwriter_buf_written_checkpoints() AS buffers_checkpoint, pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean, pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean, pg_stat_get_buf_written_backend() AS buffers_backend, pg_stat_get_buf_fsync_backend() AS buffers_backend_fsync, pg_stat_get_buf_alloc() AS buffers_alloc;
- 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, pg_stat_get_db_tuples_returned(d.oid) AS tup_returned, pg_stat_get_db_tuples_fetched(d.oid) AS tup_fetched, pg_stat_get_db_tuples_inserted(d.oid) AS tup_inserted, pg_stat_get_db_tuples_updated(d.oid) AS tup_updated, pg_stat_get_db_tuples_deleted(d.oid) AS tup_deleted FROM pg_database d;
+ 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, pg_stat_get_db_tuples_returned(d.oid) AS tup_returned, pg_stat_get_db_tuples_fetched(d.oid) AS tup_fetched, pg_stat_get_db_tuples_inserted(d.oid) AS tup_inserted, pg_stat_get_db_tuples_updated(d.oid) AS tup_updated, pg_stat_get_db_tuples_deleted(d.oid) AS tup_deleted, pg_stat_get_db_conflict_all(d.oid) AS conflicts FROM pg_database d;
+ pg_stat_database_conflicts  | SELECT d.oid AS datid, d.datname, pg_stat_get_db_conflict_tablespace(d.oid) AS confl_tablespace, pg_stat_get_db_conflict_lock(d.oid) AS confl_lock, pg_stat_get_db_conflict_snapshot(d.oid) AS confl_snapshot, pg_stat_get_db_conflict_bufferpin(d.oid) AS confl_bufferpin, pg_stat_get_db_conflict_startup_deadlock(d.oid) AS confl_deadlock FROM pg_database d;
  pg_stat_sys_indexes         | SELECT pg_stat_all_indexes.relid, pg_stat_all_indexes.indexrelid, pg_stat_all_indexes.schemaname, pg_stat_all_indexes.relname, pg_stat_all_indexes.indexrelname, pg_stat_all_indexes.idx_scan, pg_stat_all_indexes.idx_tup_read, pg_stat_all_indexes.idx_tup_fetch FROM pg_stat_all_indexes WHERE ((pg_stat_all_indexes.schemaname = ANY (ARRAY['pg_catalog'::name, 'information_schema'::name])) OR (pg_stat_all_indexes.schemaname ~ '^pg_toast'::text));
  pg_stat_sys_tables          | SELECT pg_stat_all_tables.relid, pg_stat_all_tables.schemaname, pg_stat_all_tables.relname, pg_stat_all_tables.seq_scan, pg_stat_all_tables.seq_tup_read, pg_stat_all_tables.idx_scan, pg_stat_all_tables.idx_tup_fetch, pg_stat_all_tables.n_tup_ins, pg_stat_all_tables.n_tup_upd, pg_stat_all_tables.n_tup_del, pg_stat_all_tables.n_tup_hot_upd, pg_stat_all_tables.n_live_tup, pg_stat_all_tables.n_dead_tup, pg_stat_all_tables.last_vacuum, pg_stat_all_tables.last_autovacuum, pg_stat_all_tables.last_analyze, pg_stat_all_tables.last_autoanalyze, pg_stat_all_tables.vacuum_count, pg_stat_all_tables.autovacuum_count, pg_stat_all_tables.analyze_count, pg_stat_all_tables.autoanalyze_count FROM pg_stat_all_tables WHERE ((pg_stat_all_tables.schemaname = ANY (ARRAY['pg_catalog'::name, 'information_schema'::name])) OR (pg_stat_all_tables.schemaname ~ '^pg_toast'::text));
  pg_stat_user_functions      | SELECT p.oid AS funcid, n.nspname AS schemaname, p.proname AS funcname, pg_stat_get_function_calls(p.oid) AS calls, (pg_stat_get_function_time(p.oid) / 1000) AS total_time, (pg_stat_get_function_self_time(p.oid) / 1000) AS self_time FROM (pg_proc p LEFT JOIN pg_namespace n ON ((n.oid = p.pronamespace))) WHERE ((p.prolang <> (12)::oid) AND (pg_stat_get_function_calls(p.oid) IS NOT NULL));
@@ -1334,7 +1335,7 @@ SELECT viewname, definition FROM pg_views WHERE schemaname <> 'information_schem
  shoelace_obsolete           | SELECT shoelace.sl_name, shoelace.sl_avail, shoelace.sl_color, shoelace.sl_len, shoelace.sl_unit, shoelace.sl_len_cm FROM shoelace WHERE (NOT (EXISTS (SELECT shoe.shoename FROM shoe WHERE (shoe.slcolor = shoelace.sl_color))));
  street                      | SELECT r.name, r.thepath, c.cname FROM ONLY road r, real_city c WHERE (c.outline ## r.thepath);
  toyemp                      | SELECT emp.name, emp.age, emp.location, (12 * emp.salary) AS annualsal FROM emp;
-(56 rows)
+(57 rows)
 
 SELECT tablename, rulename, definition FROM pg_rules
 	ORDER BY tablename, rulename;