Re: bad estimates

From: "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au>
To: "Ken Geis" <kgeis(at)speakeasy(dot)org>, "Bruno Wolff III" <bruno(at)wolff(dot)to>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: bad estimates
Date: 2003-08-29 08:15:05
Message-ID: 0bf301c36e05$a72f90b0$2800a8c0@mars
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> > I went through the code (7.4 beta2) that estimates the cost of an index
> > scan path. What I need to be sure of is that when running a query in
> > pgsql that uses only the columns that are in an index, the underlying
> > table need not be accessed. I know that Oracle does this.

PostgreSQL absolutely does not do this. It is also not possible to do this
due to MVCC.

Chris

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