Track last time for statistics reset on databases and bgwriter

Tracks one counter for each database, which is reset whenever
the statistics for any individual object inside the database is
reset, and one counter for the background writer.

Tomas Vondra, reviewed by Greg Smith

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index ca83421..2e8427a 100644 (file)
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -267,7 +267,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
       by backends (that is, not by the background writer), how many times
       those backends had to execute their own fsync calls (normally the
       background writer handles those even when the backend does its own
-      write), and total buffers allocated.
+      write), total buffers allocated, and time of last statistics reset.
      </entry>
      </row>
 
@@ -278,9 +278,9 @@ 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, and
+      number of rows returned, fetched, inserted, updated and deleted, the
       total number of queries cancelled due to conflict with recovery (on
-      standby servers).
+      standby servers), and time of last statistics reset.
      </entry>
      </row>
 
@@ -663,6 +663,19 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
      </row>
 
      <row>
+      <entry><literal><function>pg_stat_get_db_stat_reset_time</function>(<type>oid</type>)</literal></entry>
+      <entry><type>timestamptz</type></entry>
+      <entry>
+       Time of the last statistics reset for the database.  Initialized to the
+       system time during the first connection to each database.  The reset time
+       is updated when you call <function>pg_stat_reset</function> on the
+       database, as well as upon execution of
+       <function>pg_stat_reset_single_table_counters</function> against any
+       table or index in it.
+      </entry>
+     </row>
+
+     <row>
       <entry><literal><function>pg_stat_get_numscans</function>(<type>oid</type>)</literal></entry>
       <entry><type>bigint</type></entry>
       <entry>
@@ -1127,6 +1140,16 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
      </row>
 
      <row>
+      <entry><literal><function>pg_stat_get_bgwriter_stat_reset_time()</function></literal></entry>
+      <entry><type>timestamptz</type></entry>
+      <entry>
+        Time of the last statistics reset for the background writer, updated
+        when executing <function>pg_stat_reset_shared('bgwriter')</function>
+        on the database cluster.
+      </entry>
+     </row>
+
+     <row>
       <entry><literal><function>pg_stat_get_buf_written_backend()</function></literal></entry>
       <entry><type>bigint</type></entry>
       <entry>

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 987026c..e1d91af 100644 (file)
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -530,7 +530,8 @@ CREATE VIEW pg_stat_database AS
             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_conflict_all(D.oid) AS conflicts,
+            pg_stat_get_db_stat_reset_time(D.oid) AS stats_reset
     FROM pg_database D;
 
 CREATE VIEW pg_stat_database_conflicts AS
@@ -577,7 +578,8 @@ CREATE VIEW pg_stat_bgwriter AS
         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_buf_alloc() AS buffers_alloc,
+        pg_stat_get_bgwriter_stat_reset_time() AS stats_reset;
 
 CREATE VIEW pg_user_mappings AS
     SELECT

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 301568f..b391b48 100644 (file)
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3160,6 +3160,8 @@ pgstat_get_db_entry(Oid databaseid, bool create)
                result->n_conflict_bufferpin = 0;
                result->n_conflict_startup_deadlock = 0;
 
+               result->stat_reset_timestamp = GetCurrentTimestamp();
+
                memset(&hash_ctl, 0, sizeof(hash_ctl));
                hash_ctl.keysize = sizeof(Oid);
                hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
@@ -3440,6 +3442,12 @@ pgstat_read_statsfile(Oid onlydb, bool permanent)
        memset(&globalStats, 0, sizeof(globalStats));
 
        /*
+        * Set the current timestamp (will be kept only in case we can't load an
+        * existing statsfile.
+        */
+       globalStats.stat_reset_timestamp = GetCurrentTimestamp();
+
+       /*
         * Try to open the status file. If it doesn't exist, the backends simply
         * return zero for anything and the collector simply starts from scratch
         * with empty counters.
@@ -4052,6 +4060,8 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
        dbentry->n_tuples_deleted = 0;
        dbentry->last_autovac_time = 0;
 
+       dbentry->stat_reset_timestamp = GetCurrentTimestamp();
+
        memset(&hash_ctl, 0, sizeof(hash_ctl));
        hash_ctl.keysize = sizeof(Oid);
        hash_ctl.entrysize = sizeof(PgStat_StatTabEntry);
@@ -4083,6 +4093,7 @@ pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len)
        {
                /* Reset the global background writer statistics for the cluster. */
                memset(&globalStats, 0, sizeof(globalStats));
+               globalStats.stat_reset_timestamp = GetCurrentTimestamp();
        }
 
        /*
@@ -4107,6 +4118,8 @@ pgstat_recv_resetsinglecounter(PgStat_MsgResetsinglecounter *msg, int len)
        if (!dbentry)
                return;
 
+       /* Set the reset timestamp for the whole database */
+       dbentry->stat_reset_timestamp = GetCurrentTimestamp();
 
        /* Remove object if it exists, ignore it if not */
        if (msg->m_resettype == RESET_TABLE)

diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a95ba8b..f8f9961 100644 (file)
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -77,12 +77,14 @@ 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_stat_reset_time(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);
 extern Datum pg_stat_get_bgwriter_buf_written_checkpoints(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_bgwriter_buf_written_clean(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS);
+extern Datum pg_stat_get_bgwriter_stat_reset_time(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_buf_fsync_backend(PG_FUNCTION_ARGS);
 extern Datum pg_stat_get_buf_alloc(PG_FUNCTION_ARGS);
@@ -1136,6 +1138,24 @@ pg_stat_get_db_tuples_deleted(PG_FUNCTION_ARGS)
 }
 
 Datum
+pg_stat_get_db_stat_reset_time(PG_FUNCTION_ARGS)
+{
+       Oid                     dbid = PG_GETARG_OID(0);
+       TimestampTz result;
+       PgStat_StatDBEntry *dbentry;
+
+       if ((dbentry = pgstat_fetch_stat_dbentry(dbid)) == NULL)
+               result = 0;
+       else
+               result = dbentry->stat_reset_timestamp;
+
+       if (result == 0)
+               PG_RETURN_NULL();
+       else
+               PG_RETURN_TIMESTAMPTZ(result);
+}
+
+Datum
 pg_stat_get_db_conflict_tablespace(PG_FUNCTION_ARGS)
 {
        Oid                     dbid = PG_GETARG_OID(0);
@@ -1261,6 +1281,12 @@ pg_stat_get_bgwriter_maxwritten_clean(PG_FUNCTION_ARGS)
 }
 
 Datum
+pg_stat_get_bgwriter_stat_reset_time(PG_FUNCTION_ARGS)
+{
+       PG_RETURN_TIMESTAMPTZ(pgstat_fetch_global()->stat_reset_timestamp);
+}
+
+Datum
 pg_stat_get_buf_written_backend(PG_FUNCTION_ARGS)
 {
        PG_RETURN_INT64(pgstat_fetch_global()->buf_written_backend);

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 18739ad..aa40e22 100644 (file)
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*                                                     yyyymmddN */
-#define CATALOG_VERSION_NO     201102091
+#define CATALOG_VERSION_NO     201102101
 
 #endif

diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 9e6ec3d..01b002a 100644 (file)
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -3131,6 +3131,8 @@ 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 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 = 3074 (  pg_stat_get_db_stat_reset_time PGNSP PGUID 12 1 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 = 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_ ));
@@ -3141,6 +3143,8 @@ DATA(insert OID = 2772 ( pg_stat_get_bgwriter_buf_written_clean PGNSP PGUID 12 1
 DESCR("statistics: number of buffers written by the bgwriter for cleaning dirty buffers");
 DATA(insert OID = 2773 ( pg_stat_get_bgwriter_maxwritten_clean PGNSP PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_bgwriter_maxwritten_clean _null_ _null_ _null_ ));
 DESCR("statistics: number of times the bgwriter stopped processing when it had written too many buffers while cleaning");
+DATA(insert OID = 3075 ( pg_stat_get_bgwriter_stat_reset_time PGNSP PGUID 12 1 0 0 f f f t f s 0 0 1184 "" _null_ _null_ _null_ _null_ pg_stat_get_bgwriter_stat_reset_time _null_ _null_ _null_ ));
+DESCR("statistics: last reset for the bgwriter");
 DATA(insert OID = 2775 ( pg_stat_get_buf_written_backend PGNSP PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_buf_written_backend _null_ _null_ _null_ ));
 DESCR("statistics: number of buffers written by backends");
 DATA(insert OID = 3063 ( pg_stat_get_buf_fsync_backend PGNSP PGUID 12 1 0 0 f f f t f s 0 0 20 "" _null_ _null_ _null_ _null_ pg_stat_get_buf_fsync_backend _null_ _null_ _null_ ));

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 9f4e0ca..0414b19 100644 (file)
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -484,7 +484,7 @@ typedef union PgStat_Msg
  * ------------------------------------------------------------
  */
 
-#define PGSTAT_FILE_FORMAT_ID  0x01A5BC98
+#define PGSTAT_FILE_FORMAT_ID  0x01A5BC99
 
 /* ----------
  * PgStat_StatDBEntry                  The collector's data per database
@@ -508,6 +508,7 @@ typedef struct PgStat_StatDBEntry
        PgStat_Counter n_conflict_snapshot;
        PgStat_Counter n_conflict_bufferpin;
        PgStat_Counter n_conflict_startup_deadlock;
+       TimestampTz stat_reset_timestamp;
 
 
        /*
@@ -584,6 +585,7 @@ typedef struct PgStat_GlobalStats
        PgStat_Counter buf_written_backend;
        PgStat_Counter buf_fsync_backend;
        PgStat_Counter buf_alloc;
+       TimestampTz stat_reset_timestamp;
 } PgStat_GlobalStats;
 
 

diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 8ddc116..b494678 100644 (file)
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1294,8 +1294,8 @@ SELECT viewname, definition FROM pg_views WHERE schemaname <> 'information_schem
  pg_stat_activity            | SELECT s.datid, d.datname, s.procpid, s.usesysid, u.rolname AS usename, s.application_name, s.client_addr, s.client_port, s.backend_start, s.xact_start, s.query_start, s.waiting, s.current_query FROM pg_database d, pg_stat_get_activity(NULL::integer) s(datid, procpid, usesysid, application_name, current_query, waiting, xact_start, query_start, backend_start, client_addr, client_port), pg_authid u WHERE ((s.datid = d.oid) AND (s.usesysid = 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_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, pg_stat_get_db_conflict_all(d.oid) AS conflicts FROM pg_database d;
+ 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_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.procpid, s.usesysid, u.rolname AS usename, s.application_name, s.client_addr, s.client_port, s.backend_start, w.state, w.sent_location FROM pg_stat_get_activity(NULL::integer) s(datid, procpid, usesysid, application_name, current_query, waiting, xact_start, query_start, backend_start, client_addr, client_port), pg_authid u, pg_stat_get_wal_senders() w(procpid, state, sent_location) WHERE ((s.usesysid = u.oid) AND (s.procpid = w.procpid));
  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));