Re: Window-functions patch handling of aggregates

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: jd(at)commandprompt(dot)com
Cc: Greg Stark <greg(dot)stark(at)enterprisedb(dot)com>, Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Window-functions patch handling of aggregates
Date: 2008-12-26 19:46:48
Message-ID: 14558.1230320808@sss.pgh.pa.us
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"Joshua D. Drake" <jd(at)commandprompt(dot)com> writes:
> I believe the goal should be correctness but why not both? Fix what we
> can and put in place a "work around" that would be removed in 8.5?

Why not both what? The driving concern here is that there might be
third-party aggregates that will dump core if invoked as window
functions, and there is simply not anything we can do to prevent that.
Short of refusing to call them at all, which strikes me as an extreme
overreaction since most of them can be expected to work fine. (In
particular, if we went with solution #1 then *all* the ones that were
playing by the documented rules would still work.)

Also, there is no such thing as "a workaround we can remove in 8.5".
If we put in something like a "safe as window function" attribute for
CREATE AGGREGATE, we'll have to support it till the end of time.

regards, tom lane

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