How to launch parallel aggregations ? - Mailing list pgsql-hackers

From Esteban Zimanyi
Subject How to launch parallel aggregations ?
Date
Msg-id CAPqRbE5Mvc_ed7TmrOnE_VmnEzFDgSWiHctosQLotZyJGeSNJw@mail.gmail.com
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Responses Re: How to launch parallel aggregations ?
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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 !

Esteban




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