| From: | Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com> |
|---|---|
| To: | Gaël Le Mignot <gael(at)pilotsystems(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Performance regression between 8.3 and 8.4 on heavy text indexing |
| Date: | 2009-08-27 22:20:34 |
| Message-ID: | 1d4e0c10908271520q65450977yc7ddac8760079c68@mail.gmail.com |
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| Lists: | pgsql-performance |
2009/8/27 Gaël Le Mignot <gael(at)pilotsystems(dot)net>:
> The weird thing was that with the default of 100 for statistics
> target, it was worse than when we moved back to 10. So I didn't try
> with 1000, but I should have.
When you have so much data and a statistics target so low, you can't
expect the sample taken to be representative :between different runs
of ANALYZE, you can have totally different estimates and so totally
different plans. You just were lucky at 10 and unlucky at 100.
Thanks for your feedback and it's nice to see your problem solved.
--
Guillaume
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