2010/8/18 Tom Lane <tgl@sss.pgh.pa.us>:
> Pavel Stehule <pavel.stehule@gmail.com> writes:
>> 2010/8/18 Tom Lane <tgl@sss.pgh.pa.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.
>
I'll test both variant first. Maybe there are not any significant
difference between them. Now nodeAgg can build, fill a tuplesort. So I
think is natural use it. It needs only one - skip a calling a
transident function and directly call final function with external
tuplesort. Minimally you don't need 2x same code.
Regards
Pavel Stehule
> regards, tom lane
>