Add deadlock counter to pg_stat_database

Adds a counter that tracks number of deadlocks that occurred in
each database to pg_stat_database.

Magnus Hagander, reviewed by Jaime Casanova

doc/src/sgml/monitoring.sgml

@@ -283,8 +283,8 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
       read requests avoided by finding the block already in buffer cache),
       number of rows returned, fetched, inserted, updated and deleted, the
       total number of queries canceled due to conflict with recovery (on
-      standby servers), number and size of temporary files used, and time
-      of last statistics reset.
+      standby servers), number and size of temporary files used, total
+      number of deadlocks detected, and time of last statistics reset.
      </entry>
      </row>
 
@@ -909,6 +909,14 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
       </entry>
      </row>
 
+     <row>
+      <entry><literal><function>pg_stat_get_db_deadlocks</function>(<type>oid</type>)</literal></entry>
+      <entry><type>bigint</type></entry>
+      <entry>
+       Number of deadlocks detected in the 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

@@ -578,6 +578,7 @@ CREATE VIEW pg_stat_database AS
             pg_stat_get_db_conflict_all(D.oid) AS conflicts,
             pg_stat_get_db_temp_files(D.oid) AS temp_files,
             pg_stat_get_db_temp_bytes(D.oid) AS temp_bytes,
+            pg_stat_get_db_deadlocks(D.oid) AS deadlocks,
             pg_stat_get_db_stat_reset_time(D.oid) AS stats_reset
     FROM pg_database D;
 

src/backend/postmaster/pgstat.c

@@ -286,6 +286,7 @@ 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);
+static void pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len);
 static void pgstat_recv_tempfile(PgStat_MsgTempFile *msg, int len);
 
 
@@ -1340,6 +1341,24 @@ pgstat_report_recovery_conflict(int reason)
 	pgstat_send(&msg, sizeof(msg));
 }
 
+/* --------
+ * pgstat_report_deadlock() -
+ *
+ *	Tell the collector about a deadlock detected.
+ * --------
+ */
+void
+pgstat_report_deadlock(void)
+{
+	PgStat_MsgDeadlock msg;
+
+	if (pgStatSock == PGINVALID_SOCKET || !pgstat_track_counts)
+		return;
+
+	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DEADLOCK);
+	msg.m_databaseid = MyDatabaseId;
+	pgstat_send(&msg, sizeof(msg));
+}
 
 /* --------
  * pgstat_report_tempfile() -
@@ -1361,7 +1380,6 @@ pgstat_report_tempfile(size_t filesize)
 	pgstat_send(&msg, sizeof(msg));
 }
 
-;
 
 /* ----------
  * pgstat_ping() -
@@ -3242,6 +3260,10 @@ PgstatCollectorMain(int argc, char *argv[])
 					pgstat_recv_recoveryconflict((PgStat_MsgRecoveryConflict *) &msg, len);
 					break;
 
+				case PGSTAT_MTYPE_DEADLOCK:
+					pgstat_recv_deadlock((PgStat_MsgDeadlock *) &msg, len);
+					break;
+
 				case PGSTAT_MTYPE_TEMPFILE:
 					pgstat_recv_tempfile((PgStat_MsgTempFile *) &msg, len);
 					break;
@@ -3329,6 +3351,7 @@ pgstat_get_db_entry(Oid databaseid, bool create)
 		result->n_conflict_startup_deadlock = 0;
 		result->n_temp_files = 0;
 		result->n_temp_bytes = 0;
+		result->n_deadlocks = 0;
 
 		result->stat_reset_timestamp = GetCurrentTimestamp();
 
@@ -4242,6 +4265,7 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
 	dbentry->last_autovac_time = 0;
 	dbentry->n_temp_bytes = 0;
 	dbentry->n_temp_files = 0;
+	dbentry->n_deadlocks = 0;
 
 	dbentry->stat_reset_timestamp = GetCurrentTimestamp();
 
@@ -4467,6 +4491,22 @@ pgstat_recv_recoveryconflict(PgStat_MsgRecoveryConflict *msg, int len)
 	}
 }
 
+/* ----------
+ * pgstat_recv_deadlock() -
+ *
+ *	Process as DEADLOCK message.
+ * ----------
+ */
+static void
+pgstat_recv_deadlock(PgStat_MsgDeadlock *msg, int len)
+{
+	PgStat_StatDBEntry *dbentry;
+
+	dbentry = pgstat_get_db_entry(msg->m_databaseid, true);
+
+	dbentry->n_deadlocks++;
+}
+
 /* ----------
  * pgstat_recv_tempfile() -
  *
@@ -4482,7 +4522,6 @@ pgstat_recv_tempfile(PgStat_MsgTempFile *msg, int len)
 
 	dbentry->n_temp_bytes += msg->m_filesize;
 	dbentry->n_temp_files += 1;
-
 }
 
 /* ----------

src/backend/storage/lmgr/deadlock.c

@@ -938,6 +938,8 @@ DeadLockReport(void)
 					  pgstat_get_backend_current_activity(info->pid, false));
 	}
 
+	pgstat_report_deadlock();
+
 	ereport(ERROR,
 			(errcode(ERRCODE_T_R_DEADLOCK_DETECTED),
 			 errmsg("deadlock detected"),

src/backend/utils/adt/pgstatfuncs.c

@@ -78,6 +78,7 @@ 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_db_deadlocks(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_stat_reset_time(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_temp_files(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_db_temp_bytes(PG_FUNCTION_ARGS);
@@ -1341,6 +1342,21 @@ pg_stat_get_db_conflict_all(PG_FUNCTION_ARGS)
 	PG_RETURN_INT64(result);
 }
 
+Datum
+pg_stat_get_db_deadlocks(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_deadlocks);
+
+	PG_RETURN_INT64(result);
+}
+
 Datum
 pg_stat_get_bgwriter_timed_checkpoints(PG_FUNCTION_ARGS)
 {

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201201261
+#define CATALOG_VERSION_NO	201201262
 
 #endif

src/include/catalog/pg_proc.h

@@ -2634,6 +2634,8 @@ DATA(insert OID = 3069 (  pg_stat_get_db_conflict_startup_deadlock PGNSP PGUID 1
 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 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 = 3152 (  pg_stat_get_db_deadlocks PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_deadlocks _null_ _null_ _null_ ));
+DESCR("statistics: deadlocks detected in database");
 DATA(insert OID = 3074 (  pg_stat_get_db_stat_reset_time PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 1184 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_stat_reset_time _null_ _null_ _null_ ));
 DESCR("statistics: last reset for a database");
 DATA(insert OID = 3150 (  pg_stat_get_db_temp_files PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 20 "26" _null_ _null_ _null_ _null_ pg_stat_get_db_temp_files _null_ _null_ _null_ ));

src/include/pgstat.h

@@ -48,7 +48,8 @@ typedef enum StatMsgType
 	PGSTAT_MTYPE_FUNCSTAT,
 	PGSTAT_MTYPE_FUNCPURGE,
 	PGSTAT_MTYPE_RECOVERYCONFLICT,
-	PGSTAT_MTYPE_TEMPFILE
+	PGSTAT_MTYPE_TEMPFILE,
+	PGSTAT_MTYPE_DEADLOCK
 } StatMsgType;
 
 /* ----------
@@ -462,6 +463,17 @@ typedef struct PgStat_MsgFuncpurge
 	Oid			m_functionid[PGSTAT_NUM_FUNCPURGE];
 } PgStat_MsgFuncpurge;
 
+/* ----------
+ * PgStat_MsgDeadlock			Sent by the backend to tell the collector
+ *								about a deadlock that occurred.
+ * ----------
+ */
+typedef struct PgStat_MsgDeadlock
+{
+	PgStat_MsgHdr m_hdr;
+	Oid			m_databaseid;
+} PgStat_MsgDeadlock;
+
 
 /* ----------
  * PgStat_Msg					Union over all possible messages.
@@ -485,6 +497,7 @@ typedef union PgStat_Msg
 	PgStat_MsgFuncstat msg_funcstat;
 	PgStat_MsgFuncpurge msg_funcpurge;
 	PgStat_MsgRecoveryConflict msg_recoveryconflict;
+	PgStat_MsgDeadlock msg_deadlock;
 } PgStat_Msg;
 
 
@@ -496,7 +509,7 @@ typedef union PgStat_Msg
  * ------------------------------------------------------------
  */
 
-#define PGSTAT_FILE_FORMAT_ID	0x01A5BC99
+#define PGSTAT_FILE_FORMAT_ID	0x01A5BC9A
 
 /* ----------
  * PgStat_StatDBEntry			The collector's data per database
@@ -522,6 +535,7 @@ typedef struct PgStat_StatDBEntry
 	PgStat_Counter n_conflict_startup_deadlock;
 	PgStat_Counter n_temp_files;
 	PgStat_Counter n_temp_bytes;
+	PgStat_Counter n_deadlocks;
 
 	TimestampTz stat_reset_timestamp;
 
@@ -746,6 +760,7 @@ extern void pgstat_report_analyze(Relation rel,
 					  PgStat_Counter livetuples, PgStat_Counter deadtuples);
 
 extern void pgstat_report_recovery_conflict(int reason);
+extern void pgstat_report_deadlock(void);
 
 extern void pgstat_initialize(void);
 extern void pgstat_bestart(void);

src/test/regress/expected/rules.out

@@ -1296,7 +1296,7 @@ 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_get_bgwriter_stat_reset_time() AS stats_reset;
- 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, pg_stat_get_db_temp_files(d.oid) AS temp_files, pg_stat_get_db_temp_bytes(d.oid) AS temp_bytes, pg_stat_get_db_stat_reset_time(d.oid) AS stats_reset 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, pg_stat_get_db_temp_files(d.oid) AS temp_files, pg_stat_get_db_temp_bytes(d.oid) AS temp_bytes, pg_stat_get_db_deadlocks(d.oid) AS deadlocks, pg_stat_get_db_stat_reset_time(d.oid) AS stats_reset 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_replication             | SELECT s.pid, s.usesysid, u.rolname AS usename, s.application_name, s.client_addr, s.client_hostname, s.client_port, s.backend_start, w.state, w.sent_location, w.write_location, w.flush_location, w.replay_location, w.sync_priority, w.sync_state FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, waiting, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port), pg_authid u, pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) WHERE ((s.usesysid = u.oid) AND (s.pid = w.pid));
  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));