Re: Index of a table is not used (in any case)

From: mlw <markw(at)mohawksoft(dot)com>
To: Doug McNaught <doug(at)wireboard(dot)com>
Cc: Reiner Dassing <dassing(at)wettzell(dot)ifag(dot)de>, pgsql-sql(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Index of a table is not used (in any case)
Date: 2001-10-23 14:40:00
Message-ID: 3BD58140.F7DF625C@mohawksoft.com
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Doug McNaught wrote:

> Reiner Dassing <dassing(at)wettzell(dot)ifag(dot)de> writes:
>
> > Hello PostgreSQl Users!
> >
> > PostSQL V 7.1.1:
> >
> > I have defined a table and the necessary indices.
> > But the index is not used in every SELECT. (Therefore, the selects are
> > *very* slow, due to seq scan on
> > 20 million entries, which is a test setup up to now)
>
> Perennial first question: did you VACUUM ANALYZE?

Can there, or could there, be a notion of "rule based" optimization of
queries in PostgreSQL? The "not using index" problem is probably the most
common and most misunderstood problem.

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