| From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
|---|---|
| To: | jsarmiento(at)camaralima(dot)org(dot)pe |
| Cc: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Strange behaviour of SELECT ... IN |
| Date: | 2002-06-26 23:28:47 |
| Message-ID: | 20020627092847.B11046@svana.org |
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| Lists: | pgsql-general |
On Wed, Jun 26, 2002 at 04:00:08PM -0400, Jorge Sarmiento wrote:
> uh...
>
> the first one is an INDEX SCAN, the second one a SEQUENTIAL SCAN.
>
> number of rows in table has nothing to do...
Wrong. The number of rows has everything to do with it. If the number of
rows exceeds 50% of the table, a sequential scan is faster than an index
scan.
You can use enable_seq_scan=off to force it. Let us know if the index scan
is actually significantly faster.
Oh, you did use VACUUM ANALYZE right?
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> There are 10 kinds of people in the world, those that can do binary
> arithmetic and those that can't.
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