From 8d9a935965f01b7759a8c23ff6291000b670a2bf Mon Sep 17 00:00:00 2001 From: Fujii Masao Date: Fri, 2 Oct 2020 10:17:11 +0900 Subject: [PATCH] Add pg_stat_wal statistics view. This view shows the statistics about WAL activity. Currently it has only two columns: wal_buffers_full and stats_reset. wal_buffers_full column indicates the number of times WAL data was written to the disk because WAL buffers got full. This information is useful when tuning wal_buffers. stats_reset column indicates the time at which these statistics were last reset. pg_stat_wal view is also the basic infrastructure to expose other various statistics about WAL activity later. Bump PGSTAT_FILE_FORMAT_ID due to the change in pgstat format. Bump catalog version. Author: Masahiro Ikeda Reviewed-by: Takayuki Tsunakawa, Kyotaro Horiguchi, Amit Kapila, Fujii Masao Discussion: https://postgr.es/m/188bd3f2d2233cf97753b5ced02bb050@oss.nttdata.com --- doc/src/sgml/monitoring.sgml | 63 ++++++++++++- src/backend/access/transam/xlog.c | 1 + src/backend/catalog/system_views.sql | 6 ++ src/backend/postmaster/checkpointer.c | 3 + src/backend/postmaster/pgstat.c | 120 +++++++++++++++++++++++-- src/backend/utils/adt/pgstatfuncs.c | 36 ++++++++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 8 ++ src/include/pgstat.h | 33 ++++++- src/test/regress/expected/rules.out | 3 + src/test/regress/expected/sysviews.out | 7 ++ src/test/regress/sql/sysviews.sql | 3 + src/tools/pgindent/typedefs.list | 2 + 13 files changed, 276 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 4e0193a967..495018009a 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -424,6 +424,14 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser + + pg_stat_walpg_stat_wal + One row only, showing statistics about WAL activity. See + + pg_stat_wal for details. + + + pg_stat_databasepg_stat_database One row per database, showing database-wide statistics. See @@ -3280,6 +3288,56 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i + + <structname>pg_stat_wal</structname> + + + pg_stat_wal + + + + The pg_stat_wal view will always have a + single row, containing data about WAL activity of the cluster. + + + + <structname>pg_stat_wal</structname> View + + + + + Column Type + + + Description + + + + + + + + wal_buffers_full bigint + + + Number of times WAL data was written to the disk because WAL buffers got full + + + + + + stats_reset timestamp with time zone + + + Time at which these statistics were last reset + + + + +
+ + + <structname>pg_stat_database</structname> @@ -4668,8 +4726,9 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i argument. The argument can be bgwriter to reset all the counters shown in the pg_stat_bgwriter - view, or archiver to reset all the counters shown in - the pg_stat_archiver view. + view, archiver to reset all the counters shown in + the pg_stat_archiver view or wal + to reset all the counters shown in the pg_stat_wal view. This function is restricted to superusers by default, but other users diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 03c089b9a9..8f11b1b9de 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2196,6 +2196,7 @@ AdvanceXLInsertBuffer(XLogRecPtr upto, bool opportunistic) WriteRqst.Flush = 0; XLogWrite(WriteRqst, false); LWLockRelease(WALWriteLock); + WalStats.m_wal_buffers_full++; TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE(); } /* Re-acquire WALBufMappingLock and retry */ diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index ed4f3f142d..923c2e2be1 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -979,6 +979,12 @@ CREATE VIEW pg_stat_bgwriter AS pg_stat_get_buf_alloc() AS buffers_alloc, pg_stat_get_bgwriter_stat_reset_time() AS stats_reset; +CREATE VIEW pg_stat_wal AS + SELECT + w.wal_buffers_full, + w.stats_reset + FROM pg_stat_get_wal() w; + CREATE VIEW pg_stat_progress_analyze AS SELECT S.pid AS pid, S.datid AS datid, D.datname AS datname, diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index 3e7dcd4f76..429c8010ef 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -504,6 +504,9 @@ CheckpointerMain(void) */ pgstat_send_bgwriter(); + /* Send WAL statistics to the stats collector. */ + pgstat_send_wal(); + /* * If any checkpoint flags have been set, redo the loop to handle the * checkpoint without sleeping. diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c index e6be2b7836..5294c78549 100644 --- a/src/backend/postmaster/pgstat.c +++ b/src/backend/postmaster/pgstat.c @@ -135,11 +135,12 @@ char *pgstat_stat_filename = NULL; char *pgstat_stat_tmpname = NULL; /* - * BgWriter global statistics counters (unused in other processes). - * Stored directly in a stats message structure so it can be sent - * without needing to copy things around. We assume this inits to zeroes. + * BgWriter and WAL global statistics counters. + * Stored directly in a stats message structure so they can be sent + * without needing to copy things around. We assume these init to zeroes. */ PgStat_MsgBgWriter BgWriterStats; +PgStat_MsgWal WalStats; /* * List of SLRU names that we keep stats for. There is no central registry of @@ -281,6 +282,7 @@ static int localNumBackends = 0; */ static PgStat_ArchiverStats archiverStats; static PgStat_GlobalStats globalStats; +static PgStat_WalStats walStats; static PgStat_SLRUStats slruStats[SLRU_NUM_ELEMENTS]; /* @@ -353,6 +355,7 @@ static void pgstat_recv_vacuum(PgStat_MsgVacuum *msg, int len); static void pgstat_recv_analyze(PgStat_MsgAnalyze *msg, int len); static void pgstat_recv_archiver(PgStat_MsgArchiver *msg, int len); static void pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len); +static void pgstat_recv_wal(PgStat_MsgWal *msg, int len); static void pgstat_recv_slru(PgStat_MsgSLRU *msg, int len); static void pgstat_recv_funcstat(PgStat_MsgFuncstat *msg, int len); static void pgstat_recv_funcpurge(PgStat_MsgFuncpurge *msg, int len); @@ -938,6 +941,9 @@ pgstat_report_stat(bool force) /* Now, send function statistics */ pgstat_send_funcstats(); + /* Send WAL statistics */ + pgstat_send_wal(); + /* Finally send SLRU statistics */ pgstat_send_slru(); } @@ -1370,11 +1376,13 @@ pgstat_reset_shared_counters(const char *target) msg.m_resettarget = RESET_ARCHIVER; else if (strcmp(target, "bgwriter") == 0) msg.m_resettarget = RESET_BGWRITER; + else if (strcmp(target, "wal") == 0) + msg.m_resettarget = RESET_WAL; else ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("unrecognized reset target: \"%s\"", target), - errhint("Target must be \"archiver\" or \"bgwriter\"."))); + errhint("Target must be \"archiver\", \"bgwriter\" or \"wal\"."))); pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETSHAREDCOUNTER); pgstat_send(&msg, sizeof(msg)); @@ -2674,6 +2682,21 @@ pgstat_fetch_global(void) return &globalStats; } +/* + * --------- + * pgstat_fetch_stat_wal() - + * + * Support function for the SQL-callable pgstat* functions. Returns + * a pointer to the WAL statistics struct. + * --------- + */ +PgStat_WalStats * +pgstat_fetch_stat_wal(void) +{ + backend_read_statsfile(); + + return &walStats; +} /* * --------- @@ -4419,6 +4442,38 @@ pgstat_send_bgwriter(void) MemSet(&BgWriterStats, 0, sizeof(BgWriterStats)); } +/* ---------- + * pgstat_send_wal() - + * + * Send WAL statistics to the collector + * ---------- + */ +void +pgstat_send_wal(void) +{ + /* We assume this initializes to zeroes */ + static const PgStat_MsgWal all_zeroes; + + /* + * This function can be called even if nothing at all has happened. In + * this case, avoid sending a completely empty message to the stats + * collector. + */ + if (memcmp(&WalStats, &all_zeroes, sizeof(PgStat_MsgWal)) == 0) + return; + + /* + * Prepare and send the message + */ + pgstat_setheader(&WalStats.m_hdr, PGSTAT_MTYPE_WAL); + pgstat_send(&WalStats, sizeof(WalStats)); + + /* + * Clear out the statistics buffer, so it can be re-used. + */ + MemSet(&WalStats, 0, sizeof(WalStats)); +} + /* ---------- * pgstat_send_slru() - * @@ -4658,6 +4713,10 @@ PgstatCollectorMain(int argc, char *argv[]) pgstat_recv_bgwriter(&msg.msg_bgwriter, len); break; + case PGSTAT_MTYPE_WAL: + pgstat_recv_wal(&msg.msg_wal, len); + break; + case PGSTAT_MTYPE_SLRU: pgstat_recv_slru(&msg.msg_slru, len); break; @@ -4927,6 +4986,12 @@ pgstat_write_statsfiles(bool permanent, bool allDbs) rc = fwrite(&archiverStats, sizeof(archiverStats), 1, fpout); (void) rc; /* we'll check for error with ferror */ + /* + * Write WAL stats struct + */ + rc = fwrite(&walStats, sizeof(walStats), 1, fpout); + (void) rc; /* we'll check for error with ferror */ + /* * Write SLRU stats struct */ @@ -5186,11 +5251,12 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep) HASH_ELEM | HASH_BLOBS | HASH_CONTEXT); /* - * Clear out global and archiver statistics so they start from zero in - * case we can't load an existing statsfile. + * Clear out global, archiver, WAL and SLRU statistics so they start from + * zero in case we can't load an existing statsfile. */ memset(&globalStats, 0, sizeof(globalStats)); memset(&archiverStats, 0, sizeof(archiverStats)); + memset(&walStats, 0, sizeof(walStats)); memset(&slruStats, 0, sizeof(slruStats)); /* @@ -5199,6 +5265,7 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep) */ globalStats.stat_reset_timestamp = GetCurrentTimestamp(); archiverStats.stat_reset_timestamp = globalStats.stat_reset_timestamp; + walStats.stat_reset_timestamp = globalStats.stat_reset_timestamp; /* * Set the same reset timestamp for all SLRU items too. @@ -5268,6 +5335,17 @@ pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep) goto done; } + /* + * Read WAL stats struct + */ + if (fread(&walStats, 1, sizeof(walStats), fpin) != sizeof(walStats)) + { + ereport(pgStatRunningInCollector ? LOG : WARNING, + (errmsg("corrupted statistics file \"%s\"", statfile))); + memset(&walStats, 0, sizeof(walStats)); + goto done; + } + /* * Read SLRU stats struct */ @@ -5578,6 +5656,7 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent, PgStat_StatDBEntry dbentry; PgStat_GlobalStats myGlobalStats; PgStat_ArchiverStats myArchiverStats; + PgStat_WalStats myWalStats; PgStat_SLRUStats mySLRUStats[SLRU_NUM_ELEMENTS]; FILE *fpin; int32 format_id; @@ -5633,6 +5712,17 @@ pgstat_read_db_statsfile_timestamp(Oid databaseid, bool permanent, return false; } + /* + * Read WAL stats struct + */ + if (fread(&myWalStats, 1, sizeof(myWalStats), fpin) != sizeof(myWalStats)) + { + ereport(pgStatRunningInCollector ? LOG : WARNING, + (errmsg("corrupted statistics file \"%s\"", statfile))); + FreeFile(fpin); + return false; + } + /* * Read SLRU stats struct */ @@ -6213,6 +6303,12 @@ pgstat_recv_resetsharedcounter(PgStat_MsgResetsharedcounter *msg, int len) memset(&archiverStats, 0, sizeof(archiverStats)); archiverStats.stat_reset_timestamp = GetCurrentTimestamp(); } + else if (msg->m_resettarget == RESET_WAL) + { + /* Reset the WAL statistics for the cluster. */ + memset(&walStats, 0, sizeof(walStats)); + walStats.stat_reset_timestamp = GetCurrentTimestamp(); + } /* * Presumably the sender of this message validated the target, don't @@ -6427,6 +6523,18 @@ pgstat_recv_bgwriter(PgStat_MsgBgWriter *msg, int len) globalStats.buf_alloc += msg->m_buf_alloc; } +/* ---------- + * pgstat_recv_wal() - + * + * Process a WAL message. + * ---------- + */ +static void +pgstat_recv_wal(PgStat_MsgWal *msg, int len) +{ + walStats.wal_buffers_full += msg->m_wal_buffers_full; +} + /* ---------- * pgstat_recv_slru() - * diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index 95738a4e34..24e191ea30 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -1697,6 +1697,42 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS) PG_RETURN_INT64(pgstat_fetch_global()->buf_alloc); } +/* + * Returns statistics of WAL activity + */ +Datum +pg_stat_get_wal(PG_FUNCTION_ARGS) +{ +#define PG_STAT_GET_WAL_COLS 2 + TupleDesc tupdesc; + Datum values[PG_STAT_GET_WAL_COLS]; + bool nulls[PG_STAT_GET_WAL_COLS]; + PgStat_WalStats *wal_stats; + + /* Initialise values and NULL flags arrays */ + MemSet(values, 0, sizeof(values)); + MemSet(nulls, 0, sizeof(nulls)); + + /* Initialise attributes information in the tuple descriptor */ + tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_WAL_COLS); + TupleDescInitEntry(tupdesc, (AttrNumber) 1, "wal_buffers_full", + INT8OID, -1, 0); + TupleDescInitEntry(tupdesc, (AttrNumber) 2, "stats_reset", + TIMESTAMPTZOID, -1, 0); + + BlessTupleDesc(tupdesc); + + /* Get statistics about WAL activity */ + wal_stats = pgstat_fetch_stat_wal(); + + /* Fill values and NULLs */ + values[0] = Int64GetDatum(wal_stats->wal_buffers_full); + values[1] = TimestampTzGetDatum(wal_stats->stat_reset_timestamp); + + /* Returns the record as Datum */ + PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls))); +} + /* * Returns statistics of SLRU caches. */ diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h index 650e1f733e..1be0179724 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -53,6 +53,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 202009181 +#define CATALOG_VERSION_NO 202010021 #endif diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index f48f5fb4d9..d6f3e2d286 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -5481,6 +5481,14 @@ proname => 'pg_stat_get_buf_alloc', provolatile => 's', proparallel => 'r', prorettype => 'int8', proargtypes => '', prosrc => 'pg_stat_get_buf_alloc' }, +{ oid => '1136', descr => 'statistics: information about WAL activity', + proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's', + proparallel => 'r', prorettype => 'record', proargtypes => '', + proallargtypes => '{int8,timestamptz}', + proargmodes => '{o,o}', + proargnames => '{wal_buffers_full,stats_reset}', + prosrc => 'pg_stat_get_wal' }, + { oid => '2306', descr => 'statistics: information about SLRU caches', proname => 'pg_stat_get_slru', prorows => '100', proisstrict => 'f', proretset => 't', provolatile => 's', proparallel => 'r', diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 0dfbac46b4..343eef507e 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -61,6 +61,7 @@ typedef enum StatMsgType PGSTAT_MTYPE_ANALYZE, PGSTAT_MTYPE_ARCHIVER, PGSTAT_MTYPE_BGWRITER, + PGSTAT_MTYPE_WAL, PGSTAT_MTYPE_SLRU, PGSTAT_MTYPE_FUNCSTAT, PGSTAT_MTYPE_FUNCPURGE, @@ -122,7 +123,8 @@ typedef struct PgStat_TableCounts typedef enum PgStat_Shared_Reset_Target { RESET_ARCHIVER, - RESET_BGWRITER + RESET_BGWRITER, + RESET_WAL } PgStat_Shared_Reset_Target; /* Possible object types for resetting single counters */ @@ -436,6 +438,16 @@ typedef struct PgStat_MsgBgWriter PgStat_Counter m_checkpoint_sync_time; } PgStat_MsgBgWriter; +/* ---------- + * PgStat_MsgWal Sent by backends and background processes to update WAL statistics. + * ---------- + */ +typedef struct PgStat_MsgWal +{ + PgStat_MsgHdr m_hdr; + PgStat_Counter m_wal_buffers_full; +} PgStat_MsgWal; + /* ---------- * PgStat_MsgSLRU Sent by a backend to update SLRU statistics. * ---------- @@ -596,6 +608,7 @@ typedef union PgStat_Msg PgStat_MsgAnalyze msg_analyze; PgStat_MsgArchiver msg_archiver; PgStat_MsgBgWriter msg_bgwriter; + PgStat_MsgWal msg_wal; PgStat_MsgSLRU msg_slru; PgStat_MsgFuncstat msg_funcstat; PgStat_MsgFuncpurge msg_funcpurge; @@ -614,7 +627,7 @@ typedef union PgStat_Msg * ------------------------------------------------------------ */ -#define PGSTAT_FILE_FORMAT_ID 0x01A5BC9D +#define PGSTAT_FILE_FORMAT_ID 0x01A5BC9E /* ---------- * PgStat_StatDBEntry The collector's data per database @@ -745,6 +758,15 @@ typedef struct PgStat_GlobalStats TimestampTz stat_reset_timestamp; } PgStat_GlobalStats; +/* + * WAL statistics kept in the stats collector + */ +typedef struct PgStat_WalStats +{ + PgStat_Counter wal_buffers_full; + TimestampTz stat_reset_timestamp; +} PgStat_WalStats; + /* * SLRU statistics kept in the stats collector */ @@ -1265,6 +1287,11 @@ extern char *pgstat_stat_filename; */ extern PgStat_MsgBgWriter BgWriterStats; +/* + * WAL statistics counter is updated by backends and background processes + */ +extern PgStat_MsgWal WalStats; + /* * Updated by pgstat_count_buffer_*_time macros */ @@ -1464,6 +1491,7 @@ extern void pgstat_twophase_postabort(TransactionId xid, uint16 info, extern void pgstat_send_archiver(const char *xlog, bool failed); extern void pgstat_send_bgwriter(void); +extern void pgstat_send_wal(void); /* ---------- * Support functions for the SQL-callable functions to @@ -1478,6 +1506,7 @@ extern PgStat_StatFuncEntry *pgstat_fetch_stat_funcentry(Oid funcid); extern int pgstat_fetch_stat_numbackends(void); extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void); extern PgStat_GlobalStats *pgstat_fetch_global(void); +extern PgStat_WalStats *pgstat_fetch_stat_wal(void); extern PgStat_SLRUStats *pgstat_fetch_slru(void); extern void pgstat_count_slru_page_zeroed(int slru_idx); diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 2a18dc423e..af4192f9a8 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -2129,6 +2129,9 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid, pg_stat_all_tables.autoanalyze_count FROM pg_stat_all_tables WHERE ((pg_stat_all_tables.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (pg_stat_all_tables.schemaname !~ '^pg_toast'::text)); +pg_stat_wal| SELECT w.wal_buffers_full, + w.stats_reset + FROM pg_stat_get_wal() w(wal_buffers_full, stats_reset); pg_stat_wal_receiver| SELECT s.pid, s.status, s.receive_start_lsn, diff --git a/src/test/regress/expected/sysviews.out b/src/test/regress/expected/sysviews.out index 1cffc3349d..81bdacf59d 100644 --- a/src/test/regress/expected/sysviews.out +++ b/src/test/regress/expected/sysviews.out @@ -76,6 +76,13 @@ select count(*) >= 0 as ok from pg_prepared_xacts; t (1 row) +-- There must be only one record +select count(*) = 1 as ok from pg_stat_wal; + ok +---- + t +(1 row) + -- This is to record the prevailing planner enable_foo settings during -- a regression test run. select name, setting from pg_settings where name like 'enable%'; diff --git a/src/test/regress/sql/sysviews.sql b/src/test/regress/sql/sysviews.sql index ac4a0e1cbb..b9b875bc6a 100644 --- a/src/test/regress/sql/sysviews.sql +++ b/src/test/regress/sql/sysviews.sql @@ -37,6 +37,9 @@ select count(*) = 0 as ok from pg_prepared_statements; -- See also prepared_xacts.sql select count(*) >= 0 as ok from pg_prepared_xacts; +-- There must be only one record +select count(*) = 1 as ok from pg_stat_wal; + -- This is to record the prevailing planner enable_foo settings during -- a regression test run. select name, setting from pg_settings where name like 'enable%'; diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 9cd1179af6..4191f94869 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -1841,6 +1841,7 @@ PgStat_MsgTabpurge PgStat_MsgTabstat PgStat_MsgTempFile PgStat_MsgVacuum +PgStat_MsgWal PgStat_SLRUStats PgStat_Shared_Reset_Target PgStat_Single_Reset_Type @@ -1852,6 +1853,7 @@ PgStat_TableCounts PgStat_TableEntry PgStat_TableStatus PgStat_TableXactStatus +PgStat_WalStats PgXmlErrorContext PgXmlStrictness Pg_finfo_record