From 3e54a2f32b79238cefdd946e2fc017de0883c182 Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Mon, 17 Feb 2025 07:17:49 +0000 Subject: [PATCH v7 1/4] Remove wal_[sync|write][_time] from pg_stat_wal a051e71e28a added this information into pg_stat_io (with more details and granularity), so there is no need to keep it in pg_stat_wal. This also allows to remove PendingWalStats and simplifies up coming commits related to per backend WAL statistics. --- doc/src/sgml/config.sgml | 4 +- doc/src/sgml/monitoring.sgml | 98 +++++++++++-------------- doc/src/sgml/wal.sgml | 9 ++- src/backend/access/transam/xlog.c | 27 ------- src/backend/catalog/system_views.sql | 4 - src/backend/utils/activity/pgstat_wal.c | 24 +----- src/backend/utils/adt/pgstatfuncs.c | 20 +---- src/include/catalog/pg_proc.dat | 6 +- src/include/pgstat.h | 28 ------- src/test/regress/expected/rules.out | 6 +- src/tools/pgindent/typedefs.list | 1 - 11 files changed, 57 insertions(+), 170 deletions(-) 56.1% doc/src/sgml/ 6.6% src/backend/access/transam/ 11.6% src/backend/utils/activity/ 11.0% src/backend/utils/adt/ 3.4% src/include/catalog/ 7.7% src/include/ 3.3% src/ diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 336630ce417..9fff9048551 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -8341,8 +8341,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; You can use the pg_test_timing tool to measure the overhead of timing on your system. I/O timing information is - displayed in - pg_stat_wal. + displayed in + pg_stat_io for the wal object. Only superusers and users with the appropriate SET privilege can change this setting. diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 928a6eb64b0..e645591ce53 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -2930,6 +2930,47 @@ description | Waiting for a newly initialized WAL file to reach durable storage writer. + + For the wal object: + + + + writes is the number of times WAL buffers were + written out to disk via XLogWrite request (See + for more information about the internal WAL function XLogWrite). + + + + + fsyncs is the number of times WAL files were + synced to disk via issue_xlog_fsync request (if + is on and is either + fdatasync, fsync or fsync_writethrough, + otherwise zero) (See for more information about + the internal WAL function issue_xlog_fsync). + + + + + write_time is the total amount of time spent writing + WAL buffers to disk via XLogWrite request (if + is enabled, otherwise zero). This includes the sync time when wal_sync_method + is either open_datasync or open_sync. + + + + + sync_time is the total amount of time spent syncing + WAL files to disk via issue_xlog_fsync request (if + track_wal_io_timing is enabled, fsync is + on, and wal_sync_method is either + fdatasync, fsync or fsync_writethrough, + otherwise zero). + + + + + pg_stat_io can be used to inform database tuning. For example: @@ -3255,63 +3296,6 @@ description | Waiting for a newly initialized WAL file to reach durable storage - - - wal_write bigint - - - Number of times WAL buffers were written out to disk via - XLogWrite request. - See for more information about - the internal WAL function XLogWrite. - - - - - - wal_sync bigint - - - Number of times WAL files were synced to disk via - issue_xlog_fsync request - (if is on and - is either - fdatasync, fsync or - fsync_writethrough, otherwise zero). - See for more information about - the internal WAL function issue_xlog_fsync. - - - - - - wal_write_time double precision - - - Total amount of time spent writing WAL buffers to disk via - XLogWrite request, in milliseconds - (if is enabled, - otherwise zero). This includes the sync time when - wal_sync_method is either - open_datasync or open_sync. - - - - - - wal_sync_time double precision - - - Total amount of time spent syncing WAL files to disk via - issue_xlog_fsync request, in milliseconds - (if track_wal_io_timing is enabled, - fsync is on, and - wal_sync_method is either - fdatasync, fsync or - fsync_writethrough, otherwise zero). - - - stats_reset timestamp with time zone diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index b908720adea..bb4892413fc 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -813,8 +813,8 @@ When is enabled, the total amounts of time XLogWrite writes and issue_xlog_fsync syncs WAL data to disk are counted as - wal_write_time and wal_sync_time in - , respectively. + write_time and sync_time in + for the wal object, respectively. XLogWrite is normally called by XLogInsertRecord (when there is no space for the new record in WAL buffers), XLogFlush and the WAL writer, @@ -832,8 +832,9 @@ of the setting of track_wal_io_timing, the number of times XLogWrite writes and issue_xlog_fsync syncs WAL data to disk are also - counted as wal_write and wal_sync - in pg_stat_wal, respectively. + counted as write and sync + in pg_stat_io for the wal object + respectively. diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 25a5c605404..020b99d402c 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2448,20 +2448,6 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible) pgstat_count_io_op_time(IOOBJECT_WAL, IOCONTEXT_NORMAL, IOOP_WRITE, start, 1, written); - /* - * Increment the I/O timing and the number of times WAL data - * were written out to disk. - */ - if (track_wal_io_timing) - { - instr_time end; - - INSTR_TIME_SET_CURRENT(end); - INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, end, start); - } - - PendingWalStats.wal_write++; - if (written <= 0) { char xlogfname[MAXFNAMELEN]; @@ -8767,21 +8753,8 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli) pgstat_report_wait_end(); - /* - * Increment the I/O timing and the number of times WAL files were synced. - */ - if (track_wal_io_timing) - { - instr_time end; - - INSTR_TIME_SET_CURRENT(end); - INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, end, start); - } - pgstat_count_io_op_time(IOOBJECT_WAL, IOCONTEXT_NORMAL, IOOP_FSYNC, start, 1, 0); - - PendingWalStats.wal_sync++; } /* diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql index eff0990957e..a4d2cfdcaf5 100644 --- a/src/backend/catalog/system_views.sql +++ b/src/backend/catalog/system_views.sql @@ -1189,10 +1189,6 @@ CREATE VIEW pg_stat_wal AS w.wal_fpi, w.wal_bytes, w.wal_buffers_full, - w.wal_write, - w.wal_sync, - w.wal_write_time, - w.wal_sync_time, w.stats_reset FROM pg_stat_get_wal() w; diff --git a/src/backend/utils/activity/pgstat_wal.c b/src/backend/utils/activity/pgstat_wal.c index c1ca65eb991..4dc41a4a590 100644 --- a/src/backend/utils/activity/pgstat_wal.c +++ b/src/backend/utils/activity/pgstat_wal.c @@ -21,8 +21,6 @@ #include "utils/pgstat_internal.h" -PgStat_PendingWalStats PendingWalStats = {0}; - /* * WAL usage counters saved from pgWalUsage at the previous call to * pgstat_report_wal(). This is used to calculate how much WAL usage @@ -118,17 +116,10 @@ pgstat_wal_flush_cb(bool nowait) #define WALSTAT_ACC(fld, var_to_add) \ (stats_shmem->stats.fld += var_to_add.fld) -#define WALSTAT_ACC_INSTR_TIME(fld) \ - (stats_shmem->stats.fld += INSTR_TIME_GET_MICROSEC(PendingWalStats.fld)) WALSTAT_ACC(wal_records, wal_usage_diff); WALSTAT_ACC(wal_fpi, wal_usage_diff); WALSTAT_ACC(wal_bytes, wal_usage_diff); WALSTAT_ACC(wal_buffers_full, wal_usage_diff); - WALSTAT_ACC(wal_write, PendingWalStats); - WALSTAT_ACC(wal_sync, PendingWalStats); - WALSTAT_ACC_INSTR_TIME(wal_write_time); - WALSTAT_ACC_INSTR_TIME(wal_sync_time); -#undef WALSTAT_ACC_INSTR_TIME #undef WALSTAT_ACC LWLockRelease(&stats_shmem->lock); @@ -138,11 +129,6 @@ pgstat_wal_flush_cb(bool nowait) */ prevWalUsage = pgWalUsage; - /* - * Clear out the statistics buffer, so it can be re-used. - */ - MemSet(&PendingWalStats, 0, sizeof(PendingWalStats)); - return false; } @@ -158,18 +144,12 @@ pgstat_wal_init_backend_cb(void) } /* - * To determine whether any WAL activity has occurred since last time, not - * only the number of generated WAL records but also the numbers of WAL - * writes and syncs need to be checked. Because even transaction that - * generates no WAL records can write or sync WAL data when flushing the - * data pages. + * To determine whether WAL usage happened. */ bool pgstat_wal_have_pending_cb(void) { - return pgWalUsage.wal_records != prevWalUsage.wal_records || - PendingWalStats.wal_write != 0 || - PendingWalStats.wal_sync != 0; + return pgWalUsage.wal_records != prevWalUsage.wal_records; } void diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c index e9096a88492..68e16e52ab6 100644 --- a/src/backend/utils/adt/pgstatfuncs.c +++ b/src/backend/utils/adt/pgstatfuncs.c @@ -1637,7 +1637,7 @@ pg_stat_get_backend_io(PG_FUNCTION_ARGS) Datum pg_stat_get_wal(PG_FUNCTION_ARGS) { -#define PG_STAT_GET_WAL_COLS 9 +#define PG_STAT_GET_WAL_COLS 5 TupleDesc tupdesc; Datum values[PG_STAT_GET_WAL_COLS] = {0}; bool nulls[PG_STAT_GET_WAL_COLS] = {0}; @@ -1654,15 +1654,7 @@ pg_stat_get_wal(PG_FUNCTION_ARGS) NUMERICOID, -1, 0); TupleDescInitEntry(tupdesc, (AttrNumber) 4, "wal_buffers_full", INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 5, "wal_write", - INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 6, "wal_sync", - INT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 7, "wal_write_time", - FLOAT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 8, "wal_sync_time", - FLOAT8OID, -1, 0); - TupleDescInitEntry(tupdesc, (AttrNumber) 9, "stats_reset", + TupleDescInitEntry(tupdesc, (AttrNumber) 5, "stats_reset", TIMESTAMPTZOID, -1, 0); BlessTupleDesc(tupdesc); @@ -1682,14 +1674,8 @@ pg_stat_get_wal(PG_FUNCTION_ARGS) Int32GetDatum(-1)); values[3] = Int64GetDatum(wal_stats->wal_buffers_full); - values[4] = Int64GetDatum(wal_stats->wal_write); - values[5] = Int64GetDatum(wal_stats->wal_sync); - - /* Convert counters from microsec to millisec for display */ - values[6] = Float8GetDatum(((double) wal_stats->wal_write_time) / 1000.0); - values[7] = Float8GetDatum(((double) wal_stats->wal_sync_time) / 1000.0); - values[8] = TimestampTzGetDatum(wal_stats->stat_reset_timestamp); + values[4] = TimestampTzGetDatum(wal_stats->stat_reset_timestamp); /* Returns the record as Datum */ PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls))); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 9e803d610d7..1e1626964e3 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -5950,9 +5950,9 @@ { oid => '1136', descr => 'statistics: information about WAL activity', proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's', proparallel => 'r', prorettype => 'record', proargtypes => '', - proallargtypes => '{int8,int8,numeric,int8,int8,int8,float8,float8,timestamptz}', - proargmodes => '{o,o,o,o,o,o,o,o,o}', - proargnames => '{wal_records,wal_fpi,wal_bytes,wal_buffers_full,wal_write,wal_sync,wal_write_time,wal_sync_time,stats_reset}', + proallargtypes => '{int8,int8,numeric,int8,timestamptz}', + proargmodes => '{o,o,o,o,o}', + proargnames => '{wal_records,wal_fpi,wal_bytes,wal_buffers_full,stats_reset}', prosrc => 'pg_stat_get_wal' }, { oid => '6248', descr => 'statistics: information about WAL prefetching', proname => 'pg_stat_get_recovery_prefetch', prorows => '1', proretset => 't', diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 53f2a8458e6..a3a341cc604 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -480,28 +480,9 @@ typedef struct PgStat_WalStats PgStat_Counter wal_fpi; uint64 wal_bytes; PgStat_Counter wal_buffers_full; - PgStat_Counter wal_write; - PgStat_Counter wal_sync; - PgStat_Counter wal_write_time; - PgStat_Counter wal_sync_time; TimestampTz stat_reset_timestamp; } PgStat_WalStats; -/* - * This struct stores wal-related durations as instr_time, which makes it - * cheaper and easier to accumulate them, by not requiring type - * conversions. During stats flush instr_time will be converted into - * microseconds. - */ -typedef struct PgStat_PendingWalStats -{ - PgStat_Counter wal_write; - PgStat_Counter wal_sync; - instr_time wal_write_time; - instr_time wal_sync_time; -} PgStat_PendingWalStats; - - /* * Functions in pgstat.c */ @@ -834,13 +815,4 @@ extern PGDLLIMPORT PgStat_Counter pgStatTransactionIdleTime; /* updated by the traffic cop and in errfinish() */ extern PGDLLIMPORT SessionEndType pgStatSessionEndCause; - -/* - * Variables in pgstat_wal.c - */ - -/* updated directly by backends and background processes */ -extern PGDLLIMPORT PgStat_PendingWalStats PendingWalStats; - - #endif /* PGSTAT_H */ diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out index 5baba8d39ff..62f69ac20b2 100644 --- a/src/test/regress/expected/rules.out +++ b/src/test/regress/expected/rules.out @@ -2259,12 +2259,8 @@ pg_stat_wal| SELECT wal_records, wal_fpi, wal_bytes, wal_buffers_full, - wal_write, - wal_sync, - wal_write_time, - wal_sync_time, stats_reset - FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, wal_write, wal_sync, wal_write_time, wal_sync_time, stats_reset); + FROM pg_stat_get_wal() w(wal_records, wal_fpi, wal_bytes, wal_buffers_full, stats_reset); pg_stat_wal_receiver| SELECT pid, status, receive_start_lsn, diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index bce4214503d..740777127e9 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -2163,7 +2163,6 @@ PgStat_KindInfo PgStat_LocalState PgStat_PendingDroppedStatsItem PgStat_PendingIO -PgStat_PendingWalStats PgStat_SLRUStats PgStat_ShmemControl PgStat_Snapshot -- 2.34.1