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

On Fri, Sep 30, 2011 at 5:23 AM, Vitalii Tymchyshyn <tivv00(at)gmail(dot)com> 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;

Nice! Your version shaved almost a full second off, now 2.5s from 3.4s
it was earlier.