Re: inconsistent/weird index usage
Hannu Krosing <hannu@tm.ee>
From: Hannu Krosing <hannu@tm.ee>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Josh Berkus <josh@agliodbs.com>, Dustin Sallings <dustin@spy.net>, pgsql-performance@postgresql.org
Date: 2004-10-02T23:20:41Z
Lists: pgsql-performance
On R, 2004-10-01 at 19:34, Tom Lane wrote: > Josh Berkus <josh@agliodbs.com> writes: > >> Most of the problem here comes from the fact that "current_date - 7" > >> isn't reducible to a constant and so the planner is making bad guesses > >> about how much of each table will be scanned. > > > I thought this was fixed in 7.4. No? > > No. It's not fixed as of CVS tip either, although there was some talk > of doing something in time for 8.0. That's weird - my 7.4.2 databases did not consider (now()-'15 min'::interval) to be a constant whereas 7.4.5 does (i.e. it does use index scan on index on datetime column) Is this somehow different for date types ? -------------- Hannu