Re: [HACKERS] Vacuum: allow usage of more than 1GB of work mem

From: Claudio Freire <klaussfreire(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Cc: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Andres Freund <andres(at)anarazel(dot)de>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, Anastasia Lubennikova <lubennikovaav(at)gmail(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Vacuum: allow usage of more than 1GB of work mem
Date: 2018-02-08 00:21:29
Message-ID: CAGTBQpbam0TbUtNOo7F6BkvXt+6o=Vkqc7jj8ru1fu43=qYQ8g@mail.gmail.com
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On Wed, Feb 7, 2018 at 8:52 PM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
>> Waiting as you say would be akin to what the patch does by putting
>> vacuum on its own parallel group.
>
> I don't think it's the same. We don't need to wait until all the
> concurrent tests are done -- we only need to wait until the transactions
> that were current when the delete finished are done, which is very
> different since each test runs tons of small transactions rather than
> one single big transaction.

Um... maybe "lock pg_class" ?

That should conflict with basically any other running transaction and
have pretty much that effect.

Attached is a version of patch 1 with that approach.

Attachment Content-Type Size
0001-Vacuum-allow-using-more-than-1GB-work-mem-v17.patch text/x-patch 26.5 KB

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