On Wed, Jul 4, 2018 at 3:36 PM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp> wrote: > > I don't produce a test case where the plan is an Append with Gather > subplans, but I'm not sure that it's a good thing to allow us to consider > such a plan because in that plan, each Gather would try to grab its own pool > of workers. Am I missing something?
If the overall join can not use parallelism, having individual child joins use parallel query might turn out to be efficient even if done one child at a time. Parallel append drastically reduces the cases where something like could be useful, but I don't think we can theoretically eliminate the need for such a plan. -- Best Wishes, Ashutosh Bapat EnterpriseDB Corporation The Postgres Database Company
