Re: proposal: tuplestore, tuplesort aggregate functions

2010/8/18 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> 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.
>

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
>