| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Shigeru HANADA <shigeru(dot)hanada(at)gmail(dot)com> |
| Cc: | Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thom Brown <thom(at)linux(dot)com>, "pgsql-hackers(at)postgreSQL(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Custom/Foreign-Join-APIs (Re: [v9.5] Custom Plan API) |
| Date: | 2015-04-29 20:12:05 |
| Message-ID: | CA+TgmobgJk08oUT2pb4L4RxxAdrgGU+CMp5CAXVfYRPhdsFNzA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Apr 27, 2015 at 5:05 AM, Shigeru HANADA
<shigeru(dot)hanada(at)gmail(dot)com> wrote:
> Currently INNER JOINs with unsafe join conditions are not pushed down, so such test is not in the suit. As you say, in theory, INNER JOINs can be pushed down even they have push-down-unsafe join conditions, because such conditions can be evaluated 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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