Re: Planner chooses multi-column index in 9.2 when maybe it should not

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Sabino Mullane <greg(at)endpoint(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Planner chooses multi-column index in 9.2 when maybe it should not
Date: 2012-10-10 23:50:45
Message-ID: 13660.1349913045@sss.pgh.pa.us
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Greg Sabino Mullane <greg(at)endpoint(dot)com> writes:
> Found a good demonstration of the problem. Here's explain analyze of a
> query on 9.2 with enable_indexonlyscan = off; This produces the exact same
> plan as 8.3. The tables in question have been analyzed. Changing
> random_page_cost has no effect. The main foobar table has 17M rows.

Can you provide a self-contained test case for this (ie, sample data)?

regards, tom lane

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