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Re: Query Optimizer + Parallel Operators

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: "Felix Schmidt (at) Oracle" <felix(dot)x(dot)schmidt(at)oracle(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Query Optimizer + Parallel Operators
Date: 2011-01-27 10:38:52
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On 26.01.2011 16:46, Felix Schmidt @ Oracle wrote:
> Everybody,
> I'm interested in the query optimizer of PostgreSQL DB. Where could I
> find useful documentation or could you send me a pointer in the source code?

The relevant source code is in src/backend/optimizer directory. If you 
google around, you'll find introductory presentations, but I can't 
recommend any particular one.

> What kind of parallelism does PostgreSQL use for operators, like
> selection or join?

The short answer is "none". Each PostgreSQL backend is a one 
single-threaded process, one query will only utilize one CPU 

If you search the archives, you'll find discussion on how it might one 
day be improved, but nothing concrete has been done.

   Heikki Linnakangas

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