| Lists: | pgsql-hackers |
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| From: | "Felix Schmidt (at) Oracle" <felix(dot)x(dot)schmidt(at)oracle(dot)com> |
|---|---|
| To: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Query Optimizer + Parallel Operators |
| Date: | 2011-01-26 14:46:49 |
| Message-ID: | 4D4033D9.6090106@oracle.com |
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| Lists: | pgsql-hackers |
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?
What kind of parallelism does PostgreSQL use for operators, like
selection or join?
Thank you
- felix
| From: | Josh Berkus <josh(at)agliodbs(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: | 2011-01-26 23:14:54 |
| Message-ID: | 4D40AAEE.1070103@agliodbs.com |
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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
| From: | Dusan Misic <promisic(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | "Felix Schmidt (at) Oracle" <felix(dot)x(dot)schmidt(at)oracle(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Query Optimizer + Parallel Operators |
| Date: | 2011-01-27 07:07:34 |
| Message-ID: | AANLkTi=aKf_HVzx7TS4MHCwphCuPz+i_Qr3nEFiSBxKo@mail.gmail.com |
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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(at)agliodbs(dot)com> wrote:
> 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
>
> --
> Sent via pgsql-hackers mailing list (pgsql-hackers(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers
>
| 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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| 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