Re: parallel index creation: maintenance_work_mem not honored?

From: Fabio Pardi <f(dot)pardi(at)portavita(dot)eu>
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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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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