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Date: Thu, 25 Aug 2005 08:10:21 -0500
From: Bruno Wolff III <bruno@wolff.to>
To: Bo Lorentsen <bl@netgroup.dk>
Cc: Michael Fuhr <mike@fuhr.org>,
	Russell Simpkins <russellsimpkins@hotmail.com>, pgsql-sql@postgresql.org
Subject: Re: Number of rows in a cursor ?
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On Thu, Aug 25, 2005 at 08:51:59 +0200,
  Bo Lorentsen <bl@netgroup.dk> wrote:
> Michael Fuhr wrote:
> 
> >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.
> > 
> >
> So if i make a but data set as result of a cursor I only "pay" for the 
> rows I actually fetch ?

There is usually some overhead for set up, though I believe quick starting
plans are favored for cursor queries.