On Mon, Jan 18, 2021 at 10:27 AM tsunakawa.ta...@fujitsu.com <tsunakawa.ta...@fujitsu.com> wrote: > > From: Amit Kapila <amit.kapil...@gmail.com> > > We already allow users to specify the degree of parallelism for all > > the parallel operations via guc's max_parallel_maintenance_workers, > > max_parallel_workers_per_gather, then we have a reloption > > parallel_workers and vacuum command has the parallel option where > > users can specify the number of workers that can be used for > > parallelism. The parallelism considers these as hints but decides > > parallelism based on some other parameters like if there are that many > > workers available, etc. Why the users would expect differently for > > parallel DML? > > I agree that the user would want to specify the degree of parallelism of DML, > too. My simple (probably silly) question was, in INSERT SELECT, > > * If the target table has 10 partitions and the source table has 100 > partitions, how would the user want to specify parameters? > > * If the source and target tables have the same number of partitions, and the > user specified different values to parallel_workers and parallel_dml_workers, > how many parallel workers would run? >
Good question. I think if we choose to have a separate parameter for DML, it can probably a boolean to just indicate whether to enable parallel DML for a specified table and use the parallel_workers specified in the table used in SELECT. -- With Regards, Amit Kapila.
