From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: James Coleman <jtc331@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>
Cc: David Johnston <david.g.johnston@gmail.com>
Cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Cc: Andres Freund <andres@anarazel.de>
Subject: Re: [DOC] Document concurrent index builds waiting on each other
Date: Wed, 13 Jan 2021 18:05:37 -0300
Message-ID: <20210113210537.GA15374@alvherre.pgsql> (raw)
In-Reply-To: <CAAaqYe-0xO2HbkyHeMYikkArkWtQCidb-5F-cAyrYPk_DkUBZQ@mail.gmail.com>
On 2021-Jan-13, James Coleman wrote:
> On Wed, Jan 13, 2021 at 12:33 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> > This is true. So I propose
> >
> > Like any long-running transaction, <command>REINDEX</command> can
> > affect which tuples can be removed by concurrent <command>VACUUM</command>
> > on any table.
>
> That sounds good to me.
Great, pushed with one more wording tweak: "REINDEX on any table can
affect ... on any other table". To pg12 and up.
I wondered about noting whether only processes in the current database
are affected, but then I noticed that the current code since commit
dc7420c2c927 uses a completely different algorithm than what we had with
GetOldestXmin() and does not consider database boundaries at all.
This doesn't sound great to me, since a misbehaved database can now
affect others ... Maybe I misunderstand that code.
--
Álvaro Herrera 39°49'30"S 73°17'W
"This is what I like so much about PostgreSQL. Most of the surprises
are of the "oh wow! That's cool" Not the "oh shit!" kind. :)"
Scott Marlowe, http://archives.postgresql.org/pgsql-admin/2008-10/msg00152.php
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Cc: alvherre@alvh.no-ip.org, jtc331@gmail.com, michael@paquier.xyz, david.g.johnston@gmail.com, pgsql-hackers@lists.postgresql.org, andres@anarazel.de
Subject: Re: [DOC] Document concurrent index builds waiting on each other
In-Reply-To: <20210113210537.GA15374@alvherre.pgsql>
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