Re: optimizing queries and indexes...

From: "Josh Berkus" <josh(at)agliodbs(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-sql(at)postgresql(dot)org
Subject: Re: optimizing queries and indexes...
Date: 2001-09-16 20:36:38
Message-ID: web-119877@davinci.ethosmedia.com
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Tom,

> [ Sorry for slow response, I've been out of town ]

Taking a much-deserved vacation, hey? Any new job plans?

> Postgres absolutely does not care: the optimizer will always consider
> both A-join-B and B-join-A orders for every join it has to do. As
> Stephan and Josh noted, you can constrain the join pairs the
> optimizer
> will consider if you use explicit-JOIN syntax --- but each pair will
> be
> considered in both directions.

Fantastic! You may want to point out to unbelievers that MS SQL Server
does not do this; if you fail to put your joins/where clauses in the
*exact* order of the indecies in SQL Server, it ignores them and does a
table scan. This is especially deadly because table scans are about 1/2
as fast in SQL Server as they are in Postgres.

-Josh

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