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Re: Getting number of matched records from query

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: Michael Owens <mike(at)mikesclutter(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Getting number of matched records from query
Date: 2003-11-02 05:58:00
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Sat, 1 Nov 2003, Michael Owens wrote:

> Isn't this information (the number of matched records) available to the
> backend --- even in the case of LIMIT? All matched records still have to be
> materialized right? Therefore the record count should be available and could
> therefore be available to the client. Is this correct?

No.  For many plans, the entire record set does not have to be fully
materialized in the presence of LIMIT. In general, the limit node should
have the effect of making such plans more likely to be chosen.

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