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From: Bo Lorentsen <bl@netgroup.dk>
To: Michael Fuhr <mike@fuhr.org>
Cc: Russell Simpkins <russellsimpkins@hotmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Number of rows in a cursor ?
Date: Thu, 25 Aug 2005 08:51:59 +0200
Message-ID: <430D6A8F.6000404@netgroup.dk> (raw)
In-Reply-To: <20050824174612.GB80642@winnie.fuhr.org>
References: <B74B7433CDDD2C4AA41D94832E32E19D92EE9A@EMEXM1112.dir.svc.accenture.com>
	<430C4C70.2010005@netgroup.dk>
	<BAY103-DAV72BF461390EA073012267B5A80@phx.gbl>
	<430C6CFF.9070304@netgroup.dk>
	<20050824131921.GA39444@winnie.fuhr.org>
	<430C842C.8000504@netgroup.dk>
	<20050824174612.GB80642@winnie.fuhr.org>

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 ?

/BL

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