Re: [HACKERS] Slow count(*) again...

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Bruce Momjian <bruce@momjian.us>, Mladen Gogala <mladen.gogala@vmsinfo.com>, Greg Smith <greg@2ndquadrant.com>, Andrew Dunstan <andrew@dunslane.net>, "david@lang.hm" <david@lang.hm>, Craig Ringer <craig@postnewspapers.com.au>, Vitalii Tymchyshyn <tivv00@gmail.com>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>

Date: 2011-02-03T17:46:48Z

Lists: pgsql-hackers, pgsql-performance

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