| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Sort performance cliff with small work_mem |
| Date: | 2018-05-02 16:14:33 |
| Message-ID: | CAH2-Wz=jq+3WZWD1QcZf=uXAB_72pPzt8qQz3_EJX9bpYUDi7w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, May 2, 2018 at 8:46 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, May 2, 2018 at 11:38 AM, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>> To fix, I propose that we change the above so that we always subtract
>> tapeSpace, but if there is less than e.g. 32 kB of memory left after that
>> (including, if it went below 0), then we bump availMem back up to 32 kB. So
>> we'd always reserve 32 kB to hold the tuples, even if that means that we
>> exceed 'work_mem' slightly.
>
> Sounds very reasonable.
+1
--
Peter Geoghegan
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