Re: Really really slow select count(*) - Mailing list pgsql-performance

From Greg Smith
Subject Re: Really really slow select count(*)
Date
Msg-id 4D51A304.4070003@2ndquadrant.com
Whole thread Raw
In response to Re: Really really slow select count(*)  (Marti Raudsepp <marti@juffo.org>)
Responses Re: Really really slow select count(*)
Re: Really really slow select count(*)
List pgsql-performance
Marti Raudsepp wrote:
> I couldn't find any past discussions about changing the default to "fast".
> Are there any reasons why that cannot be done in a future release?
>

Well, it won't actually help as much as you might think.  It's possible
for clients to be in a state where fast shutdown doesn't work, either.
You either have to kill them manually or use an immediate shutdown.

Kevin and I both suggested a "fast plus timeout then immediate" behavior
is what many users seem to want.  My comments were at
http://archives.postgresql.org/pgsql-hackers/2009-09/msg01145.php ; for
an example of how fast shutdown can fail see
http://archives.postgresql.org/pgsql-bugs/2009-03/msg00062.php

--
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support  www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books


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