Horton

Re: parallel vacuum comments

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>, Peter Geoghegan <pg@bowt.ie>
Date: 2021-11-01T12:47:17Z
Lists: pgsql-hackers

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On Mon, Nov 1, 2021 at 10:44 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Sun, Oct 31, 2021 at 6:21 AM Andres Freund <andres@anarazel.de> wrote:
> >
> > Hi,
> >
> > Due to bug #17245: [1] I spent a considerably amount of time looking at vacuum
> > related code. And I found a few things that I think could stand improvement:
> >
> > - There's pretty much no tests. This is way way too complicated feature for
> >   that. If there had been tests for the obvious edge case of some indexes
> >   being too small to be handled in parallel, but others needing parallelism,
> >   the mistake leading to #17245 would have been caught during development.
>
> Yes. We should have tests at least for such cases.

For discussion, I've written a patch only for adding some tests to
parallel vacuum. The test includes the reported case where small
indexes are not processed by the leader process as well as cases where
different kinds of indexes (i.g., different amparallelvacuumoptions)
are vacuumed or cleaned up.

Regards,

--
Masahiko Sawada
EDB:  https://www.enterprisedb.com/

Commits

  1. Move parallel vacuum code to vacuumparallel.c.

  2. Move index vacuum routines to vacuum.c.

  3. Improve parallel vacuum implementation.

  4. Fix parallel amvacuumcleanup safety bug.

  5. Simplify state managed by VACUUM.