Re: inconsistent/weird index usage - Mailing list pgsql-performance

From Hannu Krosing
Subject Re: inconsistent/weird index usage
Date
Msg-id 1096759241.5508.2.camel@fuji.krosing.net
Whole thread Raw
In response to Re: inconsistent/weird index usage  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: inconsistent/weird index usage
List 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

pgsql-performance by date:

Previous
From: Russell Smith
Date:
Subject: Re: Query planner problem
Next
From: Tom Lane
Date:
Subject: Re: Query planner problem