| From: | scott ribe <scott_ribe(at)elevated-dev(dot)com> |
|---|---|
| To: | Greg Stark <stark(at)mit(dot)edu> |
| Cc: | pgsql-admin(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Estimate maintenance_work_mem for CREATE INDEX |
| Date: | 2017-12-19 14:29:29 |
| Message-ID: | 76272163-2E25-4997-9D6F-983F0BBA5885@elevated-dev.com |
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| Lists: | pgsql-admin pgsql-hackers |
> On Dec 19, 2017, at 7:14 AM, Greg Stark <stark(at)mit(dot)edu> wrote:
>
> I'm not clear how you would determine how much memory is needed to
> sort a table without actually doing the sort though. So that would be
> more of an EXPLAIN ANALYZE wouldn't it?
I'd think EXPLAIN could use a quite rough approximation, say based on a rather sparse random sampling of values. EXPLAIN ANALYZE might involve a whole table scan, or might involve more dense sampling.
--
Scott Ribe
https://www.linkedin.com/in/scottribe/
(303) 722-0567
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