Re: UNION causes horrible plan on JOIN

On Mon, Oct 28, 2019 at 3:45 PM Justin Pryzby <pryzby(at)telsasoft(dot)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.

Craig

>
>
> Justin
>

--
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Craig A. James
Chief Technology Officer
eMolecules, Inc.
3430 Carmel Mountain Road, Suite 250
San Diego, CA 92121
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