Re: SELECT Query taking 200 ms on PostgreSQL compared to 4 ms on Oracle after migration.

so 3. 4. 2021 v 19:37 odesílatel aditya desai <admad123@gmail.com> napsal:

Hi Justin/Bruce/Pavel,

Thanks for your inputs. After setting force_parallel_mode=off Execution time of same query was reduced to 1ms from 200 ms. Worked like a charm. We also increased work_mem to 80=MB. Thanks

super.

The too big max_connection can cause a lot of problems. You should install and use pgbouncer or pgpool II.

https://scalegrid.io/blog/postgresql-connection-pooling-part-4-pgbouncer-vs-pgpool/

Regards

Pavel

 

again.

Regards,

Aditya.

On Sat, Apr 3, 2021 at 9:14 PM aditya desai <admad123@gmail.com> wrote:

Thanks Justin. Will review all parameters and get back to you.

On Sat, Apr 3, 2021 at 9:11 PM Justin Pryzby <pryzby@telsasoft.com> wrote:

On Sat, Apr 03, 2021 at 11:39:19AM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > On Sat, Apr  3, 2021 at 08:38:18PM +0530, aditya desai wrote:
> >> Yes, force_parallel_mode is on. Should we set it off?
>
> > Yes.  I bet someone set it without reading our docs:
>
> >     https://www.postgresql.org/docs/13/runtime-config-query.html#RUNTIME-CONFIG-QUERY-OTHER
>
> > --> Allows the use of parallel queries for testing purposes even in cases
> > --> where no performance benefit is expected.
>
> > We might need to clarify this sentence to be clearer it is _only_ for
> > testing.
>
> I wonder why it is listed under planner options at all, and not under
> developer options.

Because it's there to help DBAs catch errors in functions incorrectly marked as
parallel safe.

--
Justin