| From: | Dieter Rehbein <dieter(dot)rehbein(at)skiline(dot)cc> |
|---|---|
| To: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: performance problem with LIMIT (order BY in DESC order). Wrong index used? |
| Date: | 2011-04-12 08:59:22 |
| Message-ID: | CF07BFEA-8AFB-4EF8-BBB1-342F6EF23CC2@skiline.cc |
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| Lists: | pgsql-performance |
what I did, was an ANALYZE, which did not change anything.
I just executed a VACUUM ANALYZE and now everything performs well. hm, strange.
thanks
Dieter
Am 12.04.2011 um 09:42 schrieb Claudio Freire:
On Tue, Apr 12, 2011 at 7:20 AM, Dieter Rehbein
<dieter(dot)rehbein(at)skiline(dot)cc> wrote:
> Hi everybody,
>
> I have a performance-problem with a query using a LIMIT. There are other threads rergading performance issues with LIMIT, but I didn't find useful hints for our problem and it might
> be interesting for other postgres-users.
Did you perform an ANALYZE or VACUUM ANALYZE?
Did you try increasing the statistic targets?
AFAIK, it looks a lot like the planner is missing stats, since it
estimates the index query on idx_nfi_newsfeed will fetch 10k rows -
instead of 25.
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