st 9. 1. 2019 v 1:07 odesÃlatel Tom Lane <t...@sss.pgh.pa.us> napsal:
> Pavel Stehule <pavel.steh...@gmail.com> writes:
> > We cannot to write
> > SELECT least(VARIADIC ARRAY[1,2,3]);
> > Attached patch add this possibility to least, greatest functions.
>
> TBH, I don't find that natural at all. If I were looking for the
> functionality "smallest element of an array", I think I'd expect to find
> that exposed as "array_smallest(anyarray) returns anyelement", not as
> some weird syntax option for LEAST.
>
The target of this patch is a consistency LEAST, GREATEST variadic
functions (implementet) with generic variadic functions.
Sure it is possible to implement array_smallest(anyarray), but it
different. This patch try to eliminate unpleasing surprising about
different behave LEAST, GREATEST from other variadic functions.
> It also seems rather inconsistent that this behaves so differently
> from, eg,
>
> =# select least(array[1,2], array[3,4]);
> least
> -------
> {1,2}
> (1 row)
>
> Normally, if you have a variadic function, it doesn't also take arrays,
> so that there's less possibility for confusion.
>
This is different case - the keyword VARIADIC was not used here.
> The implementation seems mighty ugly too, in that it has to treat this
> as entirely disjoint from MinMaxExpr's normal argument interpretation.
> But that seems like a symptom of the fact that the definition is
> disjointed itself.
>
I don't think so there is any other possibility - I have not a possibility
to unpack a array to elements inside analyze stage.
> In short, I'd rather see this done with a couple of array functions,
> independently of MinMaxExpr.
>
It doesn't help to user, when they try to use VARIADIC keyword on LEAST,
GREATEST functions.
Regards
Pavel
>
> regards, tom lane
>
