To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: Odd estimation issue with user-defined type
References: <82zkvyncaw.fsf@mid.bfk.de> <23120.1283526855@sss.pgh.pa.us>
From: Florian Weimer <fweimer@bfk.de>
Date: Fri, 03 Sep 2010 15:28:19 +0000
In-Reply-To: <23120.1283526855@sss.pgh.pa.us> (Tom Lane's message of "Fri\,
	03 Sep 2010 11\:14\:15 -0400")
Message-ID: <824oe6lucs.fsf@mid.bfk.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable

* Tom Lane:

>> Any idea what could cause this?  Do I need to provide some estimator
>> function somewhere?
>
> If you haven't, then how would you expect the planner to know that?

Perhaps it's psychic, or there is some trick I don't know about? 8-)

> Less flippantly, you really need to tell us exactly what planner support
> you did provide, before you can expect any intelligent comment.  Has the
> type got a default btree opclass?

Yes, I think so (because of CREATE OPERATOR CLASS ... USING btree).

> What selectivity estimators did you attach to the comparison
> operators?

Ah, I see, I probably need to provide a RESTRICT clause in the
operator definition.  That should do the trick, and should be fairly
easy to implement in this case.

Sorry, I just missed this piece of information in the documentation, I
should have read it more carefully.

--=20
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstra=DFe 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99