From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
Cc: | David Fetter <david(at)fetter(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: proposal: tuplestore, tuplesort aggregate functions |
Date: | 2010-08-18 15:35:19 |
Message-ID: | 19033.1282145719@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> 2010/8/18 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> There would be plenty of scope to re-use the machinery without any
>> SQL-level extensions. All you need is a polymorphic aggregate
>> transition function that maintains a tuplestore or whatever.
> Have we to use a transisdent function? If we implement median as
> special variant of aggregate - because we need to push an sort, then
> we can skip a transident function function - and call directly final
> function.
Well, that would require a whole bunch of *other* mechanisms, which you
weren't saying anything about in your original proposal. But driving
it off the transtype declaration would be quite inappropriate anyway IMO.
regards, tom lane
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