Horton

Re: Show WAL write and fsync stats in pg_stat_io

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Nazir Bilal Yavuz <byavuz81@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>, Melanie Plageman <melanieplageman@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>, "bharath.rupireddyforpostgres@gmail.com" <bharath.rupireddyforpostgres@gmail.com>, Thomas Munro <thomas.munro@gmail.com>
Date: 2025-01-24T14:20:24Z
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 →

  1. Fix copy-paste error related to the autovacuum launcher in pgstat_io.c

  2. Move SQL tests of pg_stat_io for WAL data to recovery test 029_stats_restart

  3. Add data for WAL in pg_stat_io and backend statistics

  4. Improve comment on top of pgstat_count_io_op_time()

  5. Refactor pgstat_prepare_io_time() with an input argument instead of a GUC

Hi,

On Fri, Jan 24, 2025 at 11:31:02AM +0300, Nazir Bilal Yavuz wrote:
> v9 is rebased and attached as three patches. The first one is a
> squashed patch for the current version of Andres' proposed fix to pass
> the CI, the second one is for adding WAL stats to pg_stat_io and the
> third one is for fetching timing columns from pg_stat_io in the
> pg_stat_wal view.

Thanks for the patch!

I did not look at the code yet but did a few tests.
I can see diff between pg_stat_wal and pg_stat_io, for example:

"
postgres=# select pg_stat_reset_shared();
 pg_stat_reset_shared
----------------------

(1 row)

postgres=# insert into bdt select a from generate_series(1,200000) a ;
INSERT 0 200000

postgres=# select wal_bytes,stats_reset from pg_stat_wal;
 wal_bytes |          stats_reset
-----------+-------------------------------
  11800088 | 2025-01-24 14:17:28.507994+00
(1 row)

postgres=# select sum(write_bytes),stats_reset from pg_stat_io where object = 'wal' group by stats_reset;
   sum    |          stats_reset
----------+-------------------------------
 12853248 | 2025-01-24 14:17:28.507988+00
(1 row)

Is that expected?

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
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