On Wed, Jun 03, 2020 at 06:23:57PM -0400, Philip Semanchuk wrote: > > On Jun 3, 2020, at 5:15 PM, Justin Pryzby <pryzby@xxxxxxxxxxxxx> wrote: > > What version postgres ? > > This is AWS’ version of Postgres 11.6 (“Aurora”) which of course might make a difference. > > I guess you should show an explain analyze, specifically "Workers > > Planned/Launched", maybe by linking to explain.depesz.com > > Out of an abundance of caution, our company has a policy of not pasting our plans to public servers. However, I can confirm that when I set max_parallel_workers_per_gather > 4 and the runtime increases, this is what’s in the EXPLAIN ANALYZE output: > > Workers Planned: 1 > Workers Launched: 1 Are you referring to a parallel scan/aggregate/hash/?? Are you able to show a plan for a toy query like SELECT count(col) FROM tbl , preferably including a CREATE TABLE tbl AS... ; VACUUM ANALYZE tbl; Are you able to reproduce with an unpatched postgres ? -- Justin
