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To: "David Witham" <davidw@unidial.com.au>
Cc: pgsql-sql@postgresql.org
Subject: Re: Index question 
In-reply-to: <CFA248776934FD43847E740E43C346D199DBE9@ozimelb03.ozicom.com> 
References: <CFA248776934FD43847E740E43C346D199DBE9@ozimelb03.ozicom.com>
Comments: In-reply-to "David Witham" <davidw@unidial.com.au>
	message dated "Fri, 13 Feb 2004 13:30:10 +1100"
Date: Fri, 13 Feb 2004 00:38:22 -0500
Message-ID: <28006.1076650702@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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"David Witham" <davidw@unidial.com.au> writes:
> I understand that selecting count(*) will involve a scan at some
> stage, but I was surprised that the index wasn't used in the >= case,
> but was used in the between case.

Given the estimated row counts in your examples, the planner's choices
are not surprising.  You have not given us any information on whether
those estimates are accurate.

			regards, tom lane