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Re: Much Ado About COUNT(*)

From: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
To: Jeff Davis <jdavis-pgsql(at)empires(dot)org>
Cc: Greg Stark <gsstark(at)mit(dot)edu>,"Jonah H(dot) Harris" <jharris(at)tvi(dot)edu>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Much Ado About COUNT(*)
Date: 2005-01-12 21:43:46
Message-ID: 20050112214346.GA29039@dcc.uchile.cl (view raw or flat)
Thread:
Lists: pgsql-announcepgsql-hackerspgsql-patches
On Wed, Jan 12, 2005 at 12:41:38PM -0800, Jeff Davis wrote:

> Except then the two heaps would have to be joined somehow for every
> operation. It makes sense some times to (if you have a very wide table)
> split off the rarely-accessed attributes into a seperate table to be
> joined one-to-one when those attributes are needed. To have the system
> do that automatically would create problems if the attributes that are
> split off are frequently accessed, right?

That mechanism exists right now, and it's called TOAST, dubbed the best
thing since sliced bread.  We even have documentation for it, new as of
our latest RC:

http://developer.postgresql.org/docs/postgres/storage-toast.html

-- 
Alvaro Herrera (<alvherre[(at)]dcc(dot)uchile(dot)cl>)
"El día que dejes de cambiar dejarás de vivir"

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