Horton

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

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Maciek Sakrejda <m.sakrejda@gmail.com>, Lukas Fittl <lukas@fittl.com>, Justin Pryzby <pryzby@telsasoft.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Magnus Hagander <magnus@hagander.net>, Pg Hackers <pgsql-hackers@postgresql.org>, Thomas Munro <thomas.munro@gmail.com>
Date: 2022-12-05T19:32:09Z
Lists: pgsql-hackers 
Hi,

- I think it might be worth to rename IOCONTEXT_BUFFER_POOL to
  IOCONTEXT_{NORMAL, PLAIN, DEFAULT}. I'd like at some point to track WAL IO ,
  temporary file IO etc, and it doesn't seem useful to define a version of
  BUFFER_POOL for each of them. And it'd make it less confusing, because all
  the other existing contexts are also in the buffer pool (for now, can't wait
  for "bypass" or whatever to be tracked as well).

- given that IOContextForStrategy() is defined in freelist.c, and that
  declaring it in pgstat.h requires including buf.h, I think it's probably
  better to move IOContextForStrategy()'s declaration to freelist.h (doesn't
  exist, but whatever the right one is)

- pgstat_backend_io_stats_assert_well_formed() doesn't seem to belong in
  pgstat.c. Why not pgstat_io_ops.c?

- Do pgstat_io_context_ops_assert_zero(), pgstat_io_op_assert_zero() have to
  be in pgstat.h?


I think the only non-trival thing is the first point, the rest is stuff than I
also evolve during commit.

Greetings,

Andres Freund

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.