Re: poc - possibility to write window function in PL languages

st 20. 1. 2021 v 21:32 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:

> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> > st 20. 1. 2021 v 21:07 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:
> >> Uh, what? I don't understand what this "partition context" is.
>
> > It was my name for an access to window partition local memory -
> > WinGetPartitionLocalMemory
>
> Ah.
>
> > We need some interface for this cache
>
> I'm not convinced we need to expose that, or that it'd be very
> satisfactory to plpgsql users if we did. The fact that it's fixed-size
> and initializes to zeroes are both things that are okay for C programmers
> but might be awkward to deal with in plpgsql code. At the very least it
> would greatly constrain what data types you could usefully store.
>
> So I'd be inclined to leave that out, at least for the first version.
>

I think this functionality is relatively important. If somebody tries to
implement own window function, then he starts with some variation of the
row_num function.

We can support only types of fixed length to begin.

Regards

Pavel

>
> regards, tom lane
>