On Mon, Oct 28, 2019 at 4:31 PM Justin Pryzby <pry...@telsasoft.com> wrote:
> On Mon, Oct 28, 2019 at 04:30:24PM -0700, Craig James wrote: > > On Mon, Oct 28, 2019 at 3:45 PM Justin Pryzby <pry...@telsasoft.com> > wrote: > > > > > On Mon, Oct 28, 2019 at 03:40:58PM -0700, Craig James wrote: > > > > On Postgres 9.6 (config below), I have a case I don't understand: > three > > > > tables that can be separately queried in milliseconds, but when put > > > > together into one view using UNION, take 150 seconds to query. > Here's the > > > > rough idea (actual details below): > > > > > > Do you want UNION ALL ? > > > > > > UNION without ALL distintifies the output. > > > https://www.postgresql.org/docs/current/sql-select.html#SQL-UNION > > > > > > Interesting idea, thanks. But it makes no difference. Tried it and got > the > > same bad performance. > > Could you mail the list the plan with union ALL ? > Here it is. It is indeed different, but takes 104 seconds instead of 140 seconds. https://explain.depesz.com/s/zW6I -- --------------------------------- Craig A. James Chief Technology Officer eMolecules, Inc. 3430 Carmel Mountain Road, Suite 250 San Diego, CA 92121 ---------------------------------
