$my_table =
SELECT
    1 AS id
    , 1 AS ts
    , 4 AS value1
    , 5 AS value2
UNION ALL
SELECT
    3 AS id
    , 10 AS ts
    , 40 AS value1
    , NULL AS value2
UNION ALL
SELECT
    2 AS id
    , 1 AS ts
    , NULL AS value1
    , NULL AS value2
UNION ALL
SELECT
    1 AS id
    , 2 AS ts
    , 4 AS value1
    , 5 AS value2
UNION ALL
SELECT
    3 AS id
    , 2 AS ts
    , 40 AS value1
    , NULL AS value2
UNION ALL
SELECT
    3 AS id
    , 5 AS ts
    , 2 AS value1
    , 7 AS value2
;

-- Эмуляция агрегационной функции COUNT
$cnt_create = ($_item, $_parent) -> { return 1ul };
$cnt_add = ($state, $_item, $_parent) -> { return 1ul + $state };
$cnt_merge = ($state1, $state2) -> { return $state1 + $state2 };
$cnt_get_result = ($state) -> { return $state };
$cnt_serialize = ($state) -> { return $state };
$cnt_deserialize = ($state) -> { return $state };
$cnt_default = 0l;

$cnt_udaf_factory = AggregationFactory(
	    "UDAF",
	    $cnt_create,
	    $cnt_add,
	    $cnt_merge,
	    $cnt_get_result,
	    $cnt_serialize,
	    $cnt_deserialize,
	    $cnt_default
);


SELECT
    AGGREGATE_BY(value1, $cnt_udaf_factory) AS cnt1
FROM $my_table
;