From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
---|---|
To: | Bill Moran <wmoran(at)potentialtech(dot)com> |
Cc: | SHARMILA JOTHIRAJAH <sharmi_jo(at)yahoo(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Postgresql simple query performance question |
Date: | 2007-11-07 11:34:26 |
Message-ID: | 1194435266.4251.38.camel@ebony.site |
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Lists: | pgsql-general |
On Tue, 2007-11-06 at 09:29 -0500, Bill Moran wrote:
> In response to SHARMILA JOTHIRAJAH <sharmi_jo(at)yahoo(dot)com>:
>
> > Hi
> > We are in the process of testing for migration of our database from Oracle to Postgresql.
> > I hava a simple query
> >
> > Select count(*) from foo
>
> This is asked a lot. The quick answer is that PostgreSQL method of MVCC
> makes it impossible to make this query fast. Perhaps, someday, some
> brilliant developer will come up with an optimization, but that hasn't
> happened yet.
What release level is being tested? It may already have happened.
8.3 is substantially faster at seq scans, so the tests should be re-run
on 8.3 beta.
Also, re-run the Postgres test. It should be faster the second time,
even if the database server is restarted between tests.
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
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