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Code Activity

Remove read/sync fields from pg_stat_wal and GUC track_wal_io_timing

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The four following attributes are removed from pg_stat_wal:
* wal_write
* wal_sync
* wal_write_time
* wal_sync_time

a051e71e28 has added an equivalent of this information in pg_stat_io
with more granularity as this now spreads across the backend types, IO
context and IO objects.  So, keeping the same information in pg_stat_wal
has little benefits.

Another benefit of this commit is the removal of PendingWalStats,
simplifying an upcoming patch to add per-backend WAL statistics, which
already support IO statistics and which have access to the write/sync
stats data of WAL.

The GUC track_wal_io_timing, that was used to enable or disable the
aggregation of the write and sync timings for WAL, is also removed.
pgstat_prepare_io_time() is simplified.

Bump catalog version.
Bump PGSTAT_FILE_FORMAT_ID, due to the update of PgStat_WalStats.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/Z7RkQ0EfYaqqjgz/@ip-10-97-1-34.eu-west-3.compute.internal
This commit is contained in:
Michael Paquier
2025-02-24 09:51:56 +09:00
parent fc0d0ce978
commit 2421e9a51d
20 changed files with 32 additions and 229 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
src/backend/utils/activity/pgstat_io.c
View File

@@ -83,15 +83,14 @@ pgstat_count_io_op(IOObject io_object, IOContext io_context, IOOp io_op,
}
/*
* Initialize the internal timing for an IO operation, depending on an
* IO timing GUC.
* Initialize the internal timing for an IO operation.
*/
instr_time
pgstat_prepare_io_time(bool track_io_guc)
pgstat_prepare_io_time(void)
{
instr_time io_start;
if (track_io_guc)
if (track_io_timing)
INSTR_TIME_SET_CURRENT(io_start);
else
{

24
src/backend/utils/activity/pgstat_wal.c
View File

@@ -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

20
src/backend/utils/adt/pgstatfuncs.c
View File

@@ -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)));

9
src/backend/utils/misc/guc_tables.c
View File

@@ -1500,15 +1500,6 @@ struct config_bool ConfigureNamesBool[] =
false,
NULL, NULL, NULL
},
{
{"track_wal_io_timing", PGC_SUSET, STATS_CUMULATIVE,
gettext_noop("Collects timing statistics for WAL I/O activity."),
NULL
},
&track_wal_io_timing,
false,
NULL, NULL, NULL
},
{
{"update_process_title", PGC_SUSET, PROCESS_TITLE,

1
src/backend/utils/misc/postgresql.conf.sample
View File

@@ -641,7 +641,6 @@
#track_counts = on
#track_cost_delay_timing = off
#track_io_timing = off
#track_wal_io_timing = off
#track_functions = none # none, pl, all
#stats_fetch_consistency = cache # cache, none, snapshot