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Re: SELECT * FROM <table> LIMIT 1; is really slow

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,David Blasby <dblasby(at)refractions(dot)net>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: SELECT * FROM <table> LIMIT 1; is really slow
Date: 2004-06-01 12:37:37
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Fri, 28 May 2004 21:59:53 -0400, Alvaro Herrera
<alvherre(at)dcc(dot)uchile(dot)cl> wrote:
>So the assumption was that when we see that this has
>happenned, the Cmin is no longer important (== every future command can
>already see the tuple)

If it was that simple, we wouldn't have had to invent the CMIN_IS_CMAX
flag.  This has been discussed two years ago.  Did you follow the link I
posted last week?  "Every future command" is not enough.  You have to
consider the current command and even commands started before this.


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