| 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: | Atri Sharma <atri(dot)jiit(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Vik Fearing <vik(dot)fearing(at)dalibo(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Subject: | Re: WITHIN GROUP patch |
| Date: | 2013-12-23 18:48:52 |
| Message-ID: | 87eh53mmqz.fsf@news-spur.riddles.org.uk |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
Tom> What I'm now thinking we want to do is:
Tom> 1. Non-hypothetical direct args always contribute to determining
Tom> the agg's collation.
Tom> 2. Hypothetical and aggregated args contribute to the agg's
Tom> collation only if the agg is designed so that there is always
Tom> exactly one aggregated arg (ie, it's non-variadic with one
Tom> aggregated arg). Otherwise we assign their collations
Tom> per-sort-column and don't merge them into the aggregate's
Tom> collation.
Tom> This specification ensures that a variadic aggregate doesn't
Tom> change behavior depending on how many sort columns there happen
Tom> to be.
Works for me.
--
Andrew (irc:RhodiumToad)
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