Re: UNION causes horrible plan on JOIN

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Oct 28, 2019 at 3:45 PM Justin Pryzby <pryzby@xxxxxxxxxxxxx> 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


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

[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux