Re: Suppressing unused subquery output columns

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Suppressing unused subquery output columns
Date: 2014-06-12 16:03:07
Message-ID: 26238.1402588987@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Thu, Jun 5, 2014 at 10:27 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> The attached draft patch fixes this by deleting unused output expressions
>> from unflattened subqueries, so that we get:
>> ...
>> I'm not entirely convinced that it's worth the extra planning cycles,
>> though. Given the small number of complaints to date, it might not
>> be worth doing this. Thoughts?

> I've encountered this issue before and think it would be great to fix
> it. I'm not sure precisely how many cycles it's worth paying, but
> definitely more than zero.

We have a couple votes for this patch and no one has spoken against it,
so I'll go ahead and push it into HEAD.

regards, tom lane

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