Horton

Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and more?)

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: Pavel Luzanov <p.luzanov@postgrespro.ru>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Andres Freund <andres@anarazel.de>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, tgl@sss.pgh.pa.us, vignesh21@gmail.com, lukas@fittl.com, alvherre@alvh.no-ip.org, magnus@hagander.net, pgsql-hackers@postgresql.org, thomas.munro@gmail.com, m.sakrejda@gmail.com
Date: 2023-04-03T20:50:43Z
Lists: pgsql-hackers

Attachments

On Mon, Apr 3, 2023 at 12:13 AM Pavel Luzanov <p.luzanov@postgrespro.ru> wrote:
>
> Hello,
>
> I found that the 'standalone backend' backend type is not documented
> right now.
> Adding something like (from commit message) would be helpful:
>
> Both the bootstrap backend and single user mode backends will have
> backend_type STANDALONE_BACKEND.

Thanks for the report.

Attached is a tiny patch to add standalone backend type to
pg_stat_activity documentation (referenced by pg_stat_io).

I mentioned both the bootstrap process and single user mode process in
the docs, though I can't imagine that the bootstrap process is relevant
for pg_stat_activity.

I also noticed that the pg_stat_activity docs call background workers
"parallel workers" (though it also mentions that extensions could have
other background workers registered), but this seems a bit weird because
pg_stat_activity uses GetBackendTypeDesc() and this prints "background
worker" for type B_BG_WORKER. Background workers doing parallelism tasks
is what users will most often see in pg_stat_activity, but I feel like
it is confusing to have it documented as something different than what
would appear in the view. Unless I am misunderstanding something...

- Melanie

Commits

  1. Stabilize pg_stat_io writes test

  2. Fix flakey pg_stat_io test

  3. Suppress more compiler warnings in new pgstats code.

  4. Suppress compiler warnings in new pgstats code.

  5. Add tests for pg_stat_io

  6. Create regress_tblspc in test_setup

  7. Add pg_stat_io view, providing more detailed IO statistics

  8. pgstat: Track more detailed relation IO statistics

  9. pgstat: Infrastructure for more detailed IO statistics

  10. doc: Fix some issues in logical replication section

  11. Manual cleanup and pgindent of pgstat and bufmgr related code

  12. Have the planner consider Incremental Sort for DISTINCT

  13. Use actual backend IDs in pg_stat_get_backend_idset() and friends.

  14. Remove redundant call to pgstat_report_wal()

  15. Add BackendType for standalone backends

  16. Initialize backend status reporting during bootstrap.