| From: | Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> |
|---|---|
| To: | Richard van den Berg <richard(dot)vandenberg(at)trust-factory(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Explain not accurate |
| Date: | 2004-01-12 00:24:00 |
| Message-ID: | 4001E920.5080100@familyhealth.com.au |
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| Lists: | pgsql-performance |
You need to regularly run 'analyze'.
Chris
Richard van den Berg wrote:
> Hi there,
>
> I am quite new to postgresql, and love the explain feature. It enables
> us to predict which SQL queries needs to be optimized before we see any
> problems. However, I've run into an issue where explain tells us a the
> costs of a quiry are tremendous (105849017586), but the query actually
> runs quite fast. Even "explain analyze" shows these costs.
>
> This makes me wonder: can the estimates explain shows be dead wrong?
>
> I can explain in more detail (including the query and output of explain)
> if needed. I'm using 7.4 on Solaris 8.
>
> Sincerely,
>
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