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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

42
src/backend/access/transam/xlog.c
View File

@@ -134,7 +134,6 @@ int CommitSiblings = 5; /* # concurrent xacts needed to sleep */
int wal_retrieve_retry_interval = 5000;
int max_slot_wal_keep_size_mb = -1;
int wal_decode_buffer_size = 512 * 1024;
bool track_wal_io_timing = false;
#ifdef WAL_DEBUG
bool XLOG_DEBUG = false;
@@ -2436,10 +2435,9 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
errno = 0;
/*
* Measure I/O timing to write WAL data, for pg_stat_io and/or
* pg_stat_wal.
* Measure I/O timing to write WAL data, for pg_stat_io.
*/
start = pgstat_prepare_io_time(track_io_timing || track_wal_io_timing);
start = pgstat_prepare_io_time();
pgstat_report_wait_start(WAIT_EVENT_WAL_WRITE);
written = pg_pwrite(openLogFile, from, nleft, startoffset);
@@ -2448,20 +2446,6 @@ 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];
@@ -3264,7 +3248,7 @@ XLogFileInitInternal(XLogSegNo logsegno, TimeLineID logtli,
errmsg("could not create file \"%s\": %m", tmppath)));
/* Measure I/O timing when initializing segment */
io_start = pgstat_prepare_io_time(track_io_timing);
io_start = pgstat_prepare_io_time();
pgstat_report_wait_start(WAIT_EVENT_WAL_INIT_WRITE);
save_errno = 0;
@@ -3326,7 +3310,7 @@ XLogFileInitInternal(XLogSegNo logsegno, TimeLineID logtli,
}
/* Measure I/O timing when flushing segment */
io_start = pgstat_prepare_io_time(track_io_timing);
io_start = pgstat_prepare_io_time();
pgstat_report_wait_start(WAIT_EVENT_WAL_INIT_SYNC);
if (pg_fsync(fd) != 0)
@@ -8758,10 +8742,9 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
return;
/*
* Measure I/O timing to sync the WAL file for pg_stat_io and/or
* pg_stat_wal.
* Measure I/O timing to sync the WAL file for pg_stat_io.
*/
start = pgstat_prepare_io_time(track_io_timing || track_wal_io_timing);
start = pgstat_prepare_io_time();
pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC);
switch (wal_sync_method)
@@ -8807,21 +8790,8 @@ 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++;
}
/*