Date: Wed, 24 Aug 2005 11:46:12 -0600
From: Michael Fuhr <mike@fuhr.org>
To: Bo Lorentsen <bl@netgroup.dk>
Cc: Russell Simpkins <russellsimpkins@hotmail.com>,
	pgsql-sql@postgresql.org
Subject: Re: Number of rows in a cursor ?
Message-ID: <20050824174612.GB80642@winnie.fuhr.org>
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	<BAY103-DAV72BF461390EA073012267B5A80@phx.gbl>
	<430C6CFF.9070304@netgroup.dk>
	<20050824131921.GA39444@winnie.fuhr.org>
	<430C842C.8000504@netgroup.dk>
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On Wed, Aug 24, 2005 at 04:29:00PM +0200, Bo Lorentsen wrote:
> Michael Fuhr wrote:
> >...which is the same reason a cursor doesn't know how many rows it will
> >fetch until you fetch them all (or MOVE to the end of the cursor,
> >which fetches the rows internally).
>
> So, Postgresql is not hidding something for me, it just, like me, don't 
> know ?

Right -- when you open a cursor PostgreSQL doesn't know how many
rows it will return.  PostgreSQL selects a query plan based on an
*estimate* of how many rows the query will return, but until you
fetch all the rows you can't know for sure how many rows there will
be.

-- 
Michael Fuhr