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

From Peter Geoghegan
Subject Re: Default setting for enable_hashagg_disk
Date
Msg-id CAH2-Wz=LjdJ+iedXN67g4VRwn6GHzmEGU-7gCKCFMN_XJwLhEA@mail.gmail.com
Whole thread Raw
In response to Re: Default setting for enable_hashagg_disk  (Alvaro Herrera <alvherre@2ndquadrant.com>)
List pgsql-hackers
On Fri, Jul 10, 2020 at 2:10 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> I'm not sure about this bit; sounds a bit like what has been qualified
> as "nannyism" elsewhere.  Suppose I want to give a hash table 2GB of
> memory for whatever reason.  If my work_mem is default (4MB) then I
> cannot possibly achieve that without altering both settings.
>
> So I propose that maybe we do want a maximum value, but if so it should
> be higher than what you propose.  I think 10000 is acceptable in that it
> doesn't get in the way.

That's a good point.

I amend my proposal: the maximum allowable value of
hash_mem_multiplier should be 10000.0 (i.e., ten thousand times
whatever work_mem is set to, which is subject to the existing work_mem
sizing restrictions).

-- 
Peter Geoghegan



pgsql-hackers by date:

Previous
From: Peter Geoghegan
Date:
Subject: Re: Default setting for enable_hashagg_disk
Next
From: Tom Lane
Date:
Subject: Re: Default setting for enable_hashagg_disk