On Mon, Oct 28, 2019 at 04:30:24PM -0700, Craig James wrote: > On Mon, Oct 28, 2019 at 3:45 PM Justin Pryzby <pryzby@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.
