From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert.Farrugia@go.com.mt
Cc: pgsql-admin@postgresql.org
Subject: Re: After VACUUM, statistics become skewed
Date: Sun, 25 May 2003 00:12:12 -0400
Message-ID: <3276.1053835932@sss.pgh.pa.us> (raw)
In-Reply-To: <20030523093733.0F9AC924DF1@developer.postgresql.org>
References: <20030523093733.0F9AC924DF1@developer.postgresql.org>
Robert.Farrugia@go.com.mt writes:
> Running a slightly modified query i.e. removing the in and using an
> equality, the planner uses the "correct" index this time.
Hm. What were the definitions of the two indexes, exactly?
There is an asymmetry in the planner's handling of AND/OR clauses that
can cause it to fail to recognize that a multicolumn index is usable,
depending on whether the OR clause (the IN part of your query) applies
to the first index column or a later one. I'm not sure if this relates
to your problem or not, though...
regards, tom lane
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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, Robert.Farrugia@go.com.mt
Subject: Re: After VACUUM, statistics become skewed
In-Reply-To: <3276.1053835932@sss.pgh.pa.us>
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