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To: Robert Haas <robertmhaas@gmail.com>
cc: Bruce Momjian <bruce@momjian.us>,
	Mladen Gogala <mladen.gogala@vmsinfo.com>,
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	Vitalii Tymchyshyn <tivv00@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: [HACKERS] Slow count(*) again... 
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Thu, 03 Feb 2011 12:28:29 -0500"
Date: Thu, 03 Feb 2011 12:46:48 -0500
Message-ID: <25146.1296755208@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Robert Haas <robertmhaas@gmail.com> writes:
> I don't, however, agree with his contention that this is easy to
> implement.  It would be easy to implement something that sucked.  It
> would be hard to implement something that actually helped in the cases
> where the existing settings aren't already sufficient.

Exactly.  A hint system that actually did more good than harm would be a
very nontrivial project.  IMO such effort is better spent on making the
optimizer smarter.

			regards, tom lane