| From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Strange result with LATERAL query |
| Date: | 2016-08-24 15:29:16 |
| Message-ID: | 87oa4ib36h.fsf@news-spur.riddles.org.uk |
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| Thread: | |
| Lists: | pgsql-hackers |
>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
Tom> I'm not sure if it's worth trying to distinguish whether the Param
Tom> is inside any aggregate calls or not. The existing code gets the
Tom> right answer for
Tom> select array(select x+sum(y) from generate_series(1,3) y group by y)
Tom> from generate_series(1,3) x;
Tom> and we'd be losing some efficiency for cases like that if we fix
Tom> it as above. But is it worth the trouble?
The loss of efficiency could be significant, since it's forcing a rescan
of what could be an expensive plan.
--
Andrew (irc:RhodiumToad)
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