Re: Custom/Foreign-Join-APIs (Re: [v9.5] Custom Plan API) - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Custom/Foreign-Join-APIs (Re: [v9.5] Custom Plan API)
Date
Msg-id CA+TgmobgJk08oUT2pb4L4RxxAdrgGU+CMp5CAXVfYRPhdsFNzA@mail.gmail.com
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In response to Re: Custom/Foreign-Join-APIs (Re: [v9.5] Custom Plan API)  (Shigeru HANADA <shigeru.hanada@gmail.com>)
List pgsql-hackers
On Mon, Apr 27, 2015 at 5:05 AM, Shigeru HANADA
<shigeru.hanada@gmail.com> wrote:
> Currently INNER JOINs with unsafe join conditions are not pushed down, so such test is not in the suit.  As you say,
intheory, INNER JOINs can be pushed down even they have push-down-unsafe join conditions, because such conditions can
beevaluated no local side against rows retrieved without those conditions. 

I suspect it's worth trying to do the pushdown if there is at least
one safe joinclause.  If there are none, fetching a Cartesian product
figures to be a loser.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



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