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Re: SELECT * FROM LIMIT 1; is really slow - Mailing list pgsql-hackers
From Manfred Koizar
Subject Re: SELECT * FROM LIMIT 1; is really slow
Date
Msg-id 8f0fb0drfn3rl4hj6ercgf98021894444i@email.aon.at
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In response to Re: SELECT * FROM LIMIT 1; is really slow  (Alvaro Herrera <alvherre@dcc.uchile.cl>)
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On Thu, 27 May 2004 16:50:24 -0400, Alvaro Herrera
<alvherre@dcc.uchile.cl> wrote:
>Now you are on the subject, can I ask you to take a peek at what I did
>regarding tuple headers?

I did read your patch, but I didn't understand it. :-(

>At first I thought I'd have to add back Xmax as a field on its own

Veto!  This would increase heap tuple header size ==> less tuples per
page ==> more pages per table ==> more I/O ==> performance loss.

> is there a situation
>on which we should need to peek at Cmin after setting Xmax for a
>particusar tuple?

http://archives.postgresql.org/pgsql-hackers/2002-05/msg00090.php


ServusManfred

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