Query Optimizer + Parallel Operators

Felix,

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?

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

Normally we're very helpful with this kind of information ... it's all
public after all ... but I have to say that the domain you're e-mailing
from makes it a little hard to give you a direct answer.

Could you maybe give us a little information about what you want this
information for?

--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com

This is kinda scary .....

Oracle guy asking for PostgreSQL documentation and internals of the
optimizer.

On Thu, Jan 27, 2011 at 12:14 AM, Josh Berkus <josh@agliodbs.com> wrote:

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
(http://wiki.postgresql.org/wiki/FAQ#How_does_PostgreSQL_use_CPU_resources.3F).

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
EnterpriseDB http://www.enterprisedb.com