Initial array in function to aggregate multi-dimensional array

Question

I have a table with arrays of integer.

I want to create an aggregate function that will return a 2-dimensional array with all the rows together. It then gets passed

Answer 1

Using the built-in array_cat function works.

CREATE AGGREGATE array_sum2 (int[])  (
    SFUNC     = array_cat,
    STYPE     = int[],
    INITCOND  = '{}'
);

test:

select array_sum2(array[d.a]) from (select array[1,1,2,3] as a union select array[5,8,13,21] as a) d;
       array_sum2        
-------------------------
 {{1,1,2,3},{5,8,13,21}}