Re: How to launch parallel aggregations ?

Thanks a lot! It works!

On Tue, May 18, 2021 at 11:15 AM Bharath Rupireddy <
bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:

> On Tue, May 18, 2021 at 2:32 PM Esteban Zimanyi <ezimanyi(at)ulb(dot)ac(dot)be>
> wrote:
> >
> > Dear all
> >
> > In MobilityDB we have defined parallel aggregations with a combine
> function, e.g.,
> >
> > CREATE AGGREGATE extent(tbox) (
> > SFUNC = tbox_extent_transfn,
> > STYPE = tbox,
> > COMBINEFUNC = tbox_extent_combinefn,
> > PARALLEL = safe
> > );
> >
> > We would like to trigger the combine functions in the coverage tests but
> for this it is required that the tables are VERY big. In particular for the
> above aggregation, the combine function only is triggered when the table
> has more than 300K rows.
> >
> > As it is not very effective to have such a big table in the test
> database used for the regression and the coverage tests I wonder whether it
> is possible to set some parameters to launch the combine functions with
> tables of, e.g., 10K rows, which are the bigger tables in our regression
> test database.
> >
> > Many thanks for your insights !
>
> You could do something like below, just before your test:
>
> -- encourage use of parallel plans
> set parallel_setup_cost=0;
> set parallel_tuple_cost=0;
> set min_parallel_table_scan_size=0;
> set max_parallel_workers_per_gather=2;
>
> And after the test you can reset all of the above parameters.
>
> Hope that helps!
>
> With Regards,
> Bharath Rupireddy.
> EnterpriseDB: http://www.enterprisedb.com
>