From: Josh Berkus <josh@agliodbs.com>
To: Stephan Szabo <sszabo@megazone23.bigpanda.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Indexing UNIONs
Date: Mon, 15 Jul 2002 17:31:24 -0700
Message-ID: <200207151731.24567.josh@agliodbs.com> (raw)
In-Reply-To: <20020715130911.V41271-100000@megazone23.bigpanda.com>
References: <20020715130911.V41271-100000@megazone23.bigpanda.com>
Stephan,
> We had a discussion recently on -general about this. Right now the
> planner won't push the conditions down into the arms of the union because
> noone's been sure under what conditions the optimization is safe.
So, if performance is horrible with the view, I should use a dummy table to
hold the Unioned data and index that instead?
I can understand the difficultyof optimization. However, the example I
supplied is the simplest of unions, and the two Seq Scans do seem to be
proceeding against each table seperately. I think for very simple Unions
(i.e. no grouping, no filtering within subqueries, etc.) that index usage
would be reasonable to implement.
However, I can't program it myself, so I'll have to just stick to whining and
pitiful pleading <blink puppy-dog eyes, sniffle>
--
-Josh Berkus
Aglio Database Solutions
San Francisco
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To: pgsql-sql@postgresql.org
Cc: josh@agliodbs.com, sszabo@megazone23.bigpanda.com
Subject: Re: Indexing UNIONs
In-Reply-To: <200207151731.24567.josh@agliodbs.com>
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