Re: Indexes on NULL's and order by ... limit N queries

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Maxim Boguk <mboguk(at)masterhost(dot)ru>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Indexes on NULL's and order by ... limit N queries
Date: 2008-12-01 13:22:44
Message-ID: 3032.1228137764@sss.pgh.pa.us
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Maxim Boguk <mboguk(at)masterhost(dot)ru> writes:
> Looks like when indexed search over NULL's added, planner wasn't learned right way use such index on "where something is NULL order by ... limit ..."
> queries.

There's nothing wrong with the plan; you've just got too many NULLs to
make it worth using the index for that.

regards, tom lane

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