| 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: | 4D414B3C.7020603@enterprisedb.com |
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| Thread: | |
| 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
(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
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