From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: pgsql-performance@postgresql.org
Subject: Re: checkpoints, proper config
Date: Thu, 10 Dec 2015 23:40:18 +0100
Message-ID: <5669FF52.2030303@2ndquadrant.com> (raw)
In-Reply-To: <5669B47B.9010504@commandprompt.com>
References: <CAEaSS0af0GpqQYSwePKRQq6RtX-x9NXDm=jOXcbcGAmGHXapFw@mail.gmail.com>
<5669B47B.9010504@commandprompt.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
On 12/10/2015 06:20 PM, Joshua D. Drake wrote:
> On 12/10/2015 01:12 AM, Tory M Blue wrote:
>
>> checkpoint_timeout = 5min
>>
>> checkpoint_completion_target = 0.9
>>
>
> The above is your problem. Make checkpoint_timeout = 1h . Also,
> considering turning synchronous_commit off.
I doubt that. The report mentioned that the checkpoints happen 0.027...
minutes apart (assuming the minutes_between_checkpoints is computed in a
sane way). That's way below 5 minutes, so the checkpoints have to be
triggered by something else - probably by running out of segments, but
we don't know the value before Tory increased it to 150.
Also, recommending synchronous_commit=off is a bit silly, because not
only it introduces data loss issues, but it'll likely cause even more
frequent checkpoints.
Tory, please enable logging of checkpoints (log_checkpoints=on). Also, I
don't think it makes much sense to set
(checkpoint_warning > checkpoint_timeout)
as it kinda defeats the whole purpose of the warning.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
--
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tomas.vondra@2ndquadrant.com
Subject: Re: checkpoints, proper config
In-Reply-To: <5669FF52.2030303@2ndquadrant.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox