/* syntax version 1 */
/* postgres can not */
$t = AsList(
    AsStruct(7 as a),
    AsStruct(4 as a),
    AsStruct(5 as a),
    AsStruct(1 as a),
    AsStruct(2 as a),
    AsStruct(9 as a),
    AsStruct(1 as a),
    AsStruct(9 as a));

$f = AGGREGATION_FACTORY("top", 3);

select Yql::Aggregate($t, AsTuple(), AsTuple(AsTuple(AsAtom("res"),
    $f(ListItemType(TypeOf($t)), ($z)->{ return $z.a }))));

use plato;
insert into @a select * from as_table($t);
commit;

select AGGREGATE_BY(a, $f) from @a;
select AGGREGATE_BY(distinct a, $f) from @a;