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Re: Sort performance cliff with small work_mem - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Sort performance cliff with small work_mem
Date
Msg-id CA+Tgmob-_MwpkXpKAGWs8-_m4Ph=zgqL7ZnHywgCGeP0h8i-BA@mail.gmail.com
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In response to Sort performance cliff with small work_mem  (Heikki Linnakangas <hlinnaka@iki.fi>)
Responses Re: Sort performance cliff with small work_mem  (Peter Geoghegan <pg@bowt.ie>)
Re: Sort performance cliff with small work_mem  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Wed, May 2, 2018 at 11:38 AM, Heikki Linnakangas <hlinnaka@iki.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.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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