From: | Fabio Pardi <f(dot)pardi(at)portavita(dot)eu> |
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To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
Cc: | "pgsql-admin(at)lists(dot)postgresql(dot)org" <pgsql-admin(at)lists(dot)postgresql(dot)org> |
Subject: | Re: parallel index creation: maintenance_work_mem not honored? |
Date: | 2022-06-22 06:15:34 |
Message-ID: | f815f4b2-d49f-434b-b3de-d204605de49f@portavita.eu |
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Lists: | pgsql-admin |
Thanks for the clarification Peter,
On 21/06/2022 08:46, Peter Geoghegan wrote:
>
>> But why the temp files are always on disk and not in RAM as other operations do?
> Why not?
Systems running on slow disks will probably suffer from workers writing temp files to disk.
> It is probably true that it would be better to use shared memory in
> the case where there is sufficient memory, but it's not all that
> significant compared to everything else that must happen at the same
> time. It's rarely the bottleneck. External sorts are often faster than
> internal sorts. That happens because they can be more CPU cache
> friendly, for reasons that aren't fundamental.
>
I would expect this behavior to be mentioned in the documentation.
regards,
fabio pardi
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