| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)mit(dot)edu> |
| Cc: | Peter Geoghegan <pg(at)heroku(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Robert Haas <robertmhaas(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Subject: | Re: Using quicksort for every external sort run |
| Date: | 2015-11-19 20:12:57 |
| Message-ID: | CANP8+jKsZsGc0xt0BHYvpXLGdQC+V8VpeWOVGLzpHU3Gx_FQ6w@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 19 November 2015 at 01:22, Greg Stark <stark(at)mit(dot)edu> wrote:
> Perhaps the right thing to do is report a statistic to pg_stats so
> DBAs can see how often sorts are in memory, how often they're on disk,
> and how often the on disk sort requires n passes. That would put them
> in the same category as "sequential scans" for DBAs that expect the
> application to only run index-based OLTP queries for example. The
> problem with this is that sorts are not tied to a particular relation
> and without something to group on the stat will be pretty hard to act
> on.
>
+1
We don't have a message appear when hash joins use go weird, and we
definitely don't want anything like that for sorts either.
--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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