Re: Pull up aggregate subquery

From: Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Pull up aggregate subquery
Date: 2011-05-24 02:54:55
Message-ID: BANLkTinF0sM+b-2R1rZYxgwxFcMeOqoKhg@mail.gmail.com
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2011/5/24 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Yeah.  I fixed the executor in 9.1, but got hung up on how to fix the
> planner.  So the planner still only knows how to do this for the case of
> an inner indexscan, ie, it can't handle parameterizing any piece of a
> plan larger than a single indexscan.  I have some ideas about fixing
> that but have had no time to pursue them since December :-(

If you can afford, could you describe the ideas? Or I'm glad if you
tell where to start looking. Anyway I'm going to dig into optimizer
more by myself.

> But I'm not sure
> whether the same argument can be made for arbitrary subqueries.

I guess it's hard to apply the mechanism to arbitrary subqueries, but
there are many use cases like my example, Agg node in inner.

Regards,

--
Hitoshi Harada

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