Re: array_except -- Find elements that are not common to both arrays - Mailing list pgsql-performance

On 01/10/11 01:23, Vitalii Tymchyshyn wrote:
> Since you are using except and not except all, you are not looking at
> arrays with duplicates.
> For this case next function what the fastest for me:
>
> create or replace function array_except2(anyarray,anyarray) returns
> anyarray as $$
> select ARRAY(
> (
> select r.elements
> from    (
>         (select 1,unnest($1))
>         union all
>         (select 2,unnest($2))
>         ) as r (arr, elements)
>     group by 1
>     having min(arr)=max(arr)
> ))
> $$ language sql strict immutable;
>
> Best regards, Vitalii Tymchyshyn
>
Very neat!

I could see that this function could trivially be modified to handle 3
arrays.

QUESTION: Could this be modified to take an arbitrary number of arrays?