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

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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?

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