Thread: [PERFORM] Can postgresql plan a query using multiple CPU cores?
Hi, I have a letancy-sensitive legacy application, where the time consumed by query planning was always causing some headaches. Currently it is running on postgresql-8.4 - will postgresql-10 support generating plans using multiple CPU cores to reduce the time required to generate a single plan? Thank you in advance and best regards, Clemens
On Monday, May 22, 2017, Clemens Eisserer <linuxhippy@gmail.com> wrote:
Hi,
I have a letancy-sensitive legacy application, where the time consumed
by query planning was always causing some headaches.
Currently it is running on postgresql-8.4 - will postgresql-10 support
generating plans using multiple CPU cores to reduce the time required
to generate a single plan?
My understanding, from both list monitoring and the release notes, is that query parallelization happens only during execution, not planning. A single process is still responsible for evaluating all (possibly partial) plans and picking the best one - flagging those plan steps that can leverage parallelism for possible execution.
David J.
On 23/05/17 08:21, Clemens Eisserer wrote: > Hi, > > I have a letancy-sensitive legacy application, where the time consumed > by query planning was always causing some headaches. > Currently it is running on postgresql-8.4 - will postgresql-10 support > generating plans using multiple CPU cores to reduce the time required > to generate a single plan? > > Thank you in advance and best regards, Clemens > > Hi, Might be worthwhile posting an example (query + EXPLAIN ANALYZE etc), so we can see what type of queries are resulting in long plan times. Cheers Mark
Hi
2017-05-22 22:21 GMT+02:00 Clemens Eisserer <linuxhippy@gmail.com>:
Hi,
I have a letancy-sensitive legacy application, where the time consumed
by query planning was always causing some headaches.
Currently it is running on postgresql-8.4 - will postgresql-10 support
generating plans using multiple CPU cores to reduce the time required
to generate a single plan?
no. PostgreSQL 9.6 and higher uses more CPU only for execution.
For planner speed are important GUC parameters join_collapse_limit, from_collapse_limit and show geqo_threshold.
You can try to decrease geqo_threshold - with low geqo_threshold you can increase join_collapse_limit and from_collapse_limit
Regards
Pavel
Thank you in advance and best regards, Clemens
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