From: Josh Berkus <josh@agliodbs.com>
To: pgsql-hackers@postgresql.org
To: jonah.harris@gmail.com
Cc: pryscila.lista@gmail.com
Subject: Re: About method of PostgreSQL's Optimizer
Date: Wed, 14 Sep 2005 08:44:02 -0700
Message-ID: <200509140844.03449.josh@agliodbs.com> (raw)
In-Reply-To: <36e6829205091320085993ceba@mail.gmail.com>
References: <cf0868bd05091315503024742@mail.gmail.com>
<cf0868bd05091317412310c490@mail.gmail.com>
<36e6829205091320085993ceba@mail.gmail.com>
Pryscila,
> > There are other methods for query optimization, one of them is based on
> > plan transformations (for example, using A-Star algorithm) instead of
> > plan constructions used by PostgreSQL.
We do certainly need a specific optimization for large star-schema joins. I'm
not certain that A* is suitable for our cost model, though; I think we might
need to work up something more particular to Postgres.
> > Does anyone know why this method was choosen? Are there any papers or
> > researches about it?
There probably are on ACM but I've not read them. Ours is a pretty
straightforward implementation of a cost-based optimizer. You can always
read the code ;-)
Mark Kirkwood put together this nice paper on planner statistics:
http://www.powerpostgresql.com/PlanStats
--
Josh Berkus
Aglio Database Solutions
San Francisco
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To: pgsql-performance@postgresql.org
Cc: josh@agliodbs.com, pgsql-hackers@postgresql.org, jonah.harris@gmail.com, pryscila.lista@gmail.com
Subject: Re: About method of PostgreSQL's Optimizer
In-Reply-To: <200509140844.03449.josh@agliodbs.com>
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