Horton

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

Thomas Munro <thomas.munro@enterprisedb.com>

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From: Thomas Munro <thomas.munro@enterprisedb.com>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Stephen Frost <sfrost@snowman.net>, Michael Paquier <michael.paquier@gmail.com>, Daniel Gustafsson <daniel@yesql.se>, Andres Freund <andres@anarazel.de>, Masahiko Sawada <sawada.mshk@gmail.com>, Anastasia Lubennikova <a.lubennikova@postgrespro.ru>, Anastasia Lubennikova <lubennikovaav@gmail.com>, PostgreSQL-Dev <pgsql-hackers@postgresql.org>
Date: 2018-01-25T21:21:14Z
Lists: pgsql-hackers 
On Fri, Jan 26, 2018 at 9:38 AM, Claudio Freire <klaussfreire@gmail.com> wrote:
> I had the tests running in a loop all day long, and I cannot reproduce
> that variance.
>
> Can you share your steps to reproduce it, including configure flags?

Here are two build logs where it failed:

https://travis-ci.org/postgresql-cfbot/postgresql/builds/332968819
https://travis-ci.org/postgresql-cfbot/postgresql/builds/332592511

Here's one where it succeeded:

https://travis-ci.org/postgresql-cfbot/postgresql/builds/333139855

The full build script used is:

./configure --enable-debug --enable-cassert --enable-coverage
--enable-tap-tests --with-tcl --with-python --with-perl --with-ldap
--with-icu && make -j4 all contrib docs && make -Otarget -j3
check-world

This is a virtualised 4 core system.  I wonder if "make -Otarget -j3
check-world" creates enough load on it to produce some weird timing
effect that you don't see on your development system.

-- 
Thomas Munro
http://www.enterprisedb.com

Commits

  1. Prefetch blocks during lazy vacuum's truncation scan

  2. Explain unaccounted for space in pgstattuple.