Re: array size

You may use array_length() function, e.g.
dmitigr=> SELECT array_length(ARRAY[ARRAY[1,2,3],ARRAY[4,5,6]], 1);
 array_length
--------------
            2
(1 row)

dmitigr=> SELECT array_length(ARRAY[ARRAY[1,2,3],ARRAY[4,5,6]], 2);
 array_length
--------------
            3
(1 row)

See http://www.postgresql.org/docs/9.0/static/functions-array.html