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From: Alexander Korotkov <aekorotkov@gmail.com>
Date: Sat, 8 Mar 2025 12:49:35 +0200
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Subject: Re: pgsql: reindexdb: Add the index-level REINDEX with multiple jobs
To: =?UTF-8?Q?=C3=81lvaro_Herrera?= <alvherre@alvh.no-ip.org>
Cc: Alexander Korotkov <akorotkov@postgresql.org>,
 pgsql-hackers@lists.postgresql.org,
	Maxim Orlov <orlovmg@gmail.com>,
 Svetlana Derevyanko <s.derevyanko@postgrespro.ru>
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On Fri, Mar 7, 2025 at 8:20=E2=80=AFPM =C3=81lvaro Herrera <alvherre@alvh.n=
o-ip.org> wrote:
>
> On 2024-Mar-25, Alexander Korotkov wrote:
>
> > reindexdb: Add the index-level REINDEX with multiple jobs
> >
> > Straight-forward index-level REINDEX is not supported with multiple job=
s as
> > we cannot control the concurrent processing of multiple indexes dependi=
ng on
> > the same relation.  Instead, we dedicate the whole table to certain rei=
ndex
> > job.  Thus, if indexes in the lists belong to different tables, that gi=
ves us
> > a fair level of parallelism.
>
> I tested this, because of a refactoring suggestion [1] and I find that
> it's rather completely broken.

The code was written with assumption that running
run_reindex_command() with async =3D=3D true can schedule a number of
queries for a connection.  But actually that's not true and everything
is broken.

------
Regards,
Alexander Korotkov
Supabase