Re: WAL logging problem in 9.4.3?

From: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WAL logging problem in 9.4.3?
Date: 2016-02-04 12:24:21
Message-ID: 56B342F5.1050502@iki.fi
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On 22/10/15 03:56, Michael Paquier wrote:
> On Wed, Oct 21, 2015 at 11:53 PM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:
>> Heikki Linnakangas wrote:
>>
>>> Thanks. For comparison, I wrote a patch to implement what I had in mind.
>>>
>>> When a WAL-skipping COPY begins, we add an entry for that relation in a
>>> "pending-fsyncs" hash table. Whenever we perform any action on a heap that
>>> would normally be WAL-logged, we check if the relation is in the hash table,
>>> and skip WAL-logging if so.
>>
>> I think this wasn't applied, was it?
>
> No, it was not applied.

I dropped the ball on this one back in July, so here's an attempt to
revive this thread.

I spent some time fixing the remaining issues with the prototype patch I
posted earlier, and rebased that on top of current git master. See attached.

Some review of that would be nice. If there are no major issues with it,
I'm going to create backpatchable versions of this for 9.4 and below.

- Heikki

Attachment Content-Type Size
0001-Fix-the-optimization-to-skip-WAL-logging-on-table-cr.patch text/x-diff 40.7 KB

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