Re: proposal: fix corner use case of variadic fuctions usage

On Sun, Jan 20, 2013 at 2:26 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Sat, Jan 19, 2013 at 3:27 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> That's utter nonsense. Why wouldn't people expect concat(), for
>>> example, to work for large (or even just moderate-sized) arrays?
>
>> /me blinks.
>
>> What does that have to do with anything? IIUC, the question isn't
>> whether CONCAT() would work for large arrays, but rather for very
>> large numbers of arrays written out as CONCAT(a1, ..., a10000000).
>
> No, the question is what happens with CONCAT(VARIADIC some-array-here),
> which currently just returns the array as-is, but which really ought
> to concat all the array elements as if they'd been separate arguments.

Wow, that's pretty surprising behavior.

> Pavel is claiming it's okay for that to fall over if the array has
> more than 100 elements. I disagree, not only for the specific case of
> CONCAT(), but with the more general implication that such a limitation
> is going to be okay for any VARIADIC ANY function that anyone will ever
> write.

I don't know - how many of those will there really ever be? I mean,
people only write functions as VARIADIC as a notational convenience,
don't they? If you actually need to pass more than 100 separate
pieces of data to a function, sending over 100+ parameters is almost
certainly the Wrong Way To Do It.

--
Robert Haas
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