Re: more problems with count(*) on large table

From: "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: more problems with count(*) on large table
Date: 2007-09-28 16:38:17
Message-ID: 20070928163817.GA20354@a-kretschmer.de
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

am Fri, dem 28.09.2007, um 11:56:46 -0400 mailte Mike Charnoky folgendes:
> Hi,
>
> I am still having problems performing a count(*) on a large table. This
>
> Now, certain count(*) queries are failing to complete for certain time
> ranges (I killed the query after about 24 hours). The table is indexed
> on a timestamp field. Here is one query that hangs:

Again: an index can't help! Because of MVCC: 'select count(*)' without
WHERE-condition forces an seq. table-scan.

Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Alvaro Herrera 2007-09-28 16:50:34 Re: more problems with count(*) on large table
Previous Message Tom Lane 2007-09-28 16:36:34 Re: row->ARRAY or row->table casting?