Re: type cache for concat functions

> On 20 May 2017 at 10:03, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>
> Now concat is 2x times slower than || operator. With cached FmgrInfo for
> output function it will be only 5%.

Looks nice and does what's expected (what else one may need from a Saturday
evening). I just can mention that from what I see the previous version of
`concat` is slower the more arguments are getting involved, so looks like it
can be more than 2x.

Also, it was a little bit confusing to see that the function `concat`
behaves
differently from operator `||` in terms of performance. When you're looking
at
the code it's becoming obvious, but I couldn't find any mention about that
in
the documentation.