Re: Spreading full-page writes

On 27 May 2014 13:20, Heikki Linnakangas <hlinnakangas@vmware.com> wrote:
> On 05/27/2014 03:18 PM, Simon Riggs wrote:
>>
>> IIRC Koichi had a patch for prefetch during recovery. Heikki, is that
>> the reason you also discussed changing the WAL record format to allow
>> us to identify the blocks touched by recovery more easily?
>
>
> Yeah, that was one use case I had in mind for the WAL format changes. See
> http://www.postgresql.org/message-id/533D6CBF.6080203@vmware.com.

Those proposals suggest some very big changes to the way WAL works.

Prefetch can work easily enough for most records - do we really need
that much churn?

You mentioned Btree vacuum records, but I'm planning to optimize those
another way.

Why don't we just have the prefetch code in core and forget the WAL
format changes?

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services