Re: parallel index creation: maintenance_work_mem not honored?

Hi all,

Not quite following this line of logic...  If "External sorts are often
faster than internal sorts", why bother with increasing work_mem to
avoid sorting on disk?

Regards,
Michael Vitale

Fabio Pardi wrote on 6/22/2022 2:15 AM:
> 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
>
>

Regards,

Michael Vitale

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