Almost any cross dbms migration shows a drop in performance. The engine
effectively trains developers and administrators in what works and what
doesn't. The initial migration thus compares a tuned to an untuned version.
/Aaron
----- Original Message -----
From: "Josh Berkus" <josh@agliodbs.com>
To: "Gary Doades" <gpd@gpdnet.co.uk>; <pgsql-performance@postgresql.org>
Sent: Saturday, April 03, 2004 1:59 PM
Subject: Re: [PERFORM] PostgreSQL and Linux 2.6 kernel.
> Gary,
>
> > There are no indexes on the columns involved in the update, they are
> > not required for my usual select statements. This is an attempt to
> > slightly denormalise the design to get the performance up comparable
> > to SQL Server 2000. We hope to move some of our databases over to
> > PostgreSQL later in the year and this is part of the ongoing testing.
> > SQLServer's query optimiser is a bit smarter that PostgreSQL's (yet)
> > so I am hand optimising some of the more frequently used
> > SQL and/or tweaking the database design slightly.
>
> Hmmm ... that hasn't been my general experience on complex queries.
However,
> it may be due to a difference in ANALYZE statistics. I'd love to see you
> increase your default_stats_target, re-analyze, and see if PostgreSQL gets
> "smarter".
>
> --
> -Josh Berkus
> Aglio Database Solutions
> San Francisco
>
>
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