Re: array_except -- Find elements that are not common to both arrays

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