| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Man <man(dot)trieu(at)gmail(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: How to change order sort of table in HashJoin |
| Date: | 2016-11-20 16:39:39 |
| Message-ID: | 18388.1479659979@sss.pgh.pa.us |
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| Lists: | pgsql-general pgsql-hackers |
Man <man(dot)trieu(at)gmail(dot)com> writes:
> Additional information.
> In 9.6 the second table (lesser tuple) was choosen (the same testdata).
> There are something (cost estimation?) different in previous versions.
I'd bet on different statistics in the two installations (either you
forgot to ANALYZE, or the random sample came up quite a bit different).
And I'm a little suspicious that these tests weren't all done with the
same work_mem setting.
regards, tom lane
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