Show WAL write and fsync stats in pg_stat_io

Nazir Bilal Yavuz <byavuz81@gmail.com>

From: Nazir Bilal Yavuz <byavuz81@gmail.com>

To: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2023-06-28T10:09:14Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Fix copy-paste error related to the autovacuum launcher in pgstat_io.c
- 17d8bba6dad1 18.0 landed
Move SQL tests of pg_stat_io for WAL data to recovery test 029_stats_restart
- 428fadb7e97e 18.0 landed
Add data for WAL in pg_stat_io and backend statistics
- a051e71e28a1 18.0 landed
Improve comment on top of pgstat_count_io_op_time()
- b998fedab74c 18.0 landed
Refactor pgstat_prepare_io_time() with an input argument instead of a GUC
- 3c9d9acae0bc 17.0 landed

Attachments

v1-0001-WIP-Show-WAL-write-and-fsync-stats-on-pg_stat_io.patch (application/octet-stream) patch v1-0001

Hi,

This is a WIP patch to add WAL write and fsync stats to pg_stat_io
view. There is a track_io_timing variable to control pg_stat_io
timings and a track_wal_io_timing variable to control WAL timings. I
couldn't decide on which logic to enable WAL timings on pg_stat_io.
For now, both pg_stat_io and track_wal_io_timing are needed to be
enabled to track WAL timings in pg_stat_io.

Also, if you compare WAL stats in pg_stat_wal and pg_stat_io; you can
come across differences. These differences are caused by the
background writer's WAL stats not being flushed. Because of that,
background writer's WAL stats are not seen in pg_stat_wal but in
pg_stat_io. I already sent a patch [1] to fix that.

[1] https://www.postgresql.org/message-id/CAN55FZ2FPYngovZstr%3D3w1KSEHe6toiZwrurbhspfkXe5UDocg%40mail.gmail.com

Any kind of feedback would be appreciated.

Regards,
Nazir Bilal Yavuz
Microsoft