Re: Redesigning checkpoint_segments

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: hlinnaka <hlinnaka(at)iki(dot)fi>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Venkata Balaji N <nag1010(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Redesigning checkpoint_segments
Date: 2015-06-26 13:58:22
Message-ID: CA+TgmoZJe_f9kKvzzhAY_Ow44K=i1Vk6k5G3aHfgGTni8FNrDA@mail.gmail.com
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On Fri, Jun 26, 2015 at 9:47 AM, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> On 06/26/2015 03:40 PM, Robert Haas wrote:
>> Actually, I've seen a number of presentations indicating
>> that the pacing of checkpoints is already too aggressive near the
>> beginning, because as soon as we initiate the checkpoint we have a
>> storm of full page writes. I'm sure we can come up with arbitrarily
>> complicated systems to compensate for this, but something simple might
>> be to calculate progress done+adjust/total+adjust rather than
>> done/total. If you let adjust=total/9, for example, then you
>> essentially start the progress meter at 10% instead of 0%. Even
>> something that simple might be an improvement.
>
> Yeah, but that's an unrelated issue. This was most recently discussed at
> http://www.postgresql.org/message-id/CAKHd5Ce-bnD=gEEdtXiT2_AY7shquTKd0yHXXk5F4zVEKRPX-w@mail.gmail.com.
> I posted a simple patch there - review and testing is welcome ;-).

Ah, thanks for the pointer - I had forgotten about that thread.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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