Re: Default setting for enable_hashagg_disk - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Default setting for enable_hashagg_disk
Date
Msg-id 2165606.1594418399@sss.pgh.pa.us
Whole thread Raw
In response to Re: Default setting for enable_hashagg_disk  (Stephen Frost <sfrost@snowman.net>)
Responses Re: Default setting for enable_hashagg_disk  (David Rowley <dgrowleyml@gmail.com>)
Re: Default setting for enable_hashagg_disk  (Stephen Frost <sfrost@snowman.net>)
Re: Default setting for enable_hashagg_disk  (Amit Kapila <amit.kapila16@gmail.com>)
List pgsql-hackers
Stephen Frost <sfrost@snowman.net> writes:
> I don't see hash_mem as being any kind of proper fix- it's just punting
> to the user saying "we can't figure this out, how about you do it" and,
> worse, it's in conflict with how we already ask the user that question.
> Turning it into a multiplier doesn't change that either.

Have you got a better proposal that is reasonably implementable for v13?
(I do not accept the argument that "do nothing" is a better proposal.)

I agree that hash_mem is a stopgap, whether it's a multiplier or no,
but at this point it seems difficult to avoid inventing a stopgap.
Getting rid of the process-global work_mem setting is a research project,
and one I wouldn't even count on having results from for v14.  In the
meantime, it seems dead certain that there are applications for which
the current behavior will be problematic.  hash_mem seems like a cleaner
and more useful stopgap than the "escape hatch" approach, at least to me.

            regards, tom lane



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