From: Gregory Stark <stark@enterprisedb.com>
To: <radhika@88thstreet.com>
Cc: <pgsql-sql@postgresql.org>
Subject: Re: Query Plan
In-Reply-To: <63759.63.118.86.10.1184274660.squirrel@www.88thstreet.com>
	(Radhika Sambamurti's message of "Thu, 12 Jul 2007 17:11:00 -0400
	(EDT)")
Organization: EnterpriseDB
References: <63759.63.118.86.10.1184274660.squirrel@www.88thstreet.com>
Date: Thu, 12 Jul 2007 23:14:47 +0100
Message-ID: <874pk96zhk.fsf@oxford.xeocode.com>
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"Radhika Sambamurti" <radhika@88thstreet.com> writes:

> When I run the query with combination of FirmClearingID & status the run
> times are approx 3700ms.
> But when I add tradedate ie date_trunc('day', tradedate) = '20070703' the
> run time becomes a horrendous 19631.958 ms.

I'm not really able to make heads or tails of your plans without the query.
But any where clause of the form date_trunc('...',col)='...' will always
generate crappy plans. And it looks like you already have expressions of that
form in the view even in the one which you label "without date_trunc".

Instead try to write a where clause that the database can understand the end
points of. Something like (col >= '20070703' and col < '20070704'). That's
something the database can apply a normal index to and also something it can
have a chance at guessing how many rows will fit.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com