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|
$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 = 0ul;
$cnt_udaf_factory = AggregationFactory(
"UDAF",
$cnt_create,
$cnt_add,
$cnt_merge,
$cnt_get_result,
$cnt_serialize,
$cnt_deserialize,
$cnt_default
);
SELECT
id,
AGGREGATE_BY(value1, $cnt_udaf_factory) AS cnt1
FROM $my_table
GROUP BY
id
;
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