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

Melanie Plageman <melanieplageman@gmail.com>

From: Melanie Plageman <melanieplageman@gmail.com>

To: Andres Freund <andres@anarazel.de>

Cc: 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>, Maciek Sakrejda <m.sakrejda@gmail.com>

Date: 2023-01-04T22:56:07Z

Lists: pgsql-hackers

Attachments

v44-0004-Add-system-view-tracking-IO-ops-per-backend-type.patch (application/octet-stream) patch v44-0004
v44-0002-pgstat-Infrastructure-to-track-IO-operations.patch (application/octet-stream) patch v44-0002
v44-0003-pgstat-Count-IO-for-relations.patch (application/octet-stream) patch v44-0003
v44-0001-pgindent-and-some-manual-cleanup-in-pgstat-relat.patch (application/octet-stream) patch v44-0001

On Mon, Jan 2, 2023 at 8:15 PM Melanie Plageman
<melanieplageman@gmail.com> wrote:
>
> On Mon, Jan 2, 2023 at 5:46 PM Melanie Plageman
> <melanieplageman@gmail.com> wrote:
> >
> > Besides docs, there is one large change to the code which I am currently
> > working on, which is to change PgStat_IOOpCounters into an array of
> > PgStatCounters instead of having individual members for each IOOp type.
> > I hadn't done this previously because the additional level of nesting
> > seemed confusing. However, it seems it would simplify the code quite a
> > bit and is probably worth doing.
>
> As described above, attached v43 uses an array for the PgStatCounters of
> IOOps instead of struct members.

This wasn't quite a multi-dimensional array. Attached is v44, in which I
have removed all of the granular struct types -- PgStat_IOOps,
PgStat_IOContext, and PgStat_IOObject by collapsing them into a single
array of PgStat_Counters in a new struct PgStat_BackendIO. I needed to
keep this in addition to PgStat_IO to have a data type for backends to
track their stats in locally.

I've also done another round of cleanup.

- Melanie

Commits

Stabilize pg_stat_io writes test
- ef719e7b32fc 16.0 landed
Fix flakey pg_stat_io test
- 1be0fdb9de55 16.0 landed
Suppress more compiler warnings in new pgstats code.
- b1b86820d84e 16.0 landed
Suppress compiler warnings in new pgstats code.
- 728560db7d86 16.0 landed
Add tests for pg_stat_io
- 10a082bf7215 16.0 landed
Create regress_tblspc in test_setup
- 9c83bbcf7ef6 16.0 landed
Add pg_stat_io view, providing more detailed IO statistics
- a9c70b46dbe1 16.0 landed
pgstat: Track more detailed relation IO statistics
- f30d62c2fc60 16.0 landed
pgstat: Infrastructure for more detailed IO statistics
- 28e626bde00e 16.0 landed
doc: Fix some issues in logical replication section
- 4f74f5641d53 16.0 cited
Manual cleanup and pgindent of pgstat and bufmgr related code
- 250c8ee07ede 16.0 landed
Have the planner consider Incremental Sort for DISTINCT
- 3c6fc58209f2 16.0 cited
Use actual backend IDs in pg_stat_get_backend_idset() and friends.
- d7e39d72ca1c 16.0 cited
Remove redundant call to pgstat_report_wal()
- 1bdd54e662d5 16.0 landed
Add BackendType for standalone backends
- 0c679464a837 16.0 landed
Initialize backend status reporting during bootstrap.
- 3b34645678d1 15.0 landed