-- DQ: эталонная сессия Метрики против сессии, нарезанной слоем DDS.
--
-- Сопоставление идет по куке внутри завершенного дня: лишняя сессия одной
-- куки не скрывает потерянную сессию другой. Результат содержит итог дня.
WITH
    (SELECT min(EventDate) FROM ods.event_v) AS first_source_day,
    first_source_day + ({position:UInt16} - 1) AS last_lived_day,
    reference AS
    (
        SELECT
            EventDate AS data_date,
            ClientID AS client_id,
            uniqExact(VisitID) AS sessions
        FROM ods.event_v
        WHERE EventDate <= last_lived_day
        GROUP BY
            data_date,
            client_id
    ),
    actual AS
    (
        SELECT
            session_date AS data_date,
            client_id,
            count() AS sessions
        FROM dds.session_v
        WHERE session_date <= last_lived_day
        GROUP BY
            data_date,
            client_id
    ),
    comparison AS
    (
        SELECT
            coalesce(reference.data_date, actual.data_date) AS data_date,
            toString(coalesce(reference.client_id, actual.client_id)) AS business_key,
            isNotNull(reference.client_id) AS reference_present,
            isNotNull(actual.client_id) AS actual_present,
            toString(reference.sessions) AS reference_value,
            toString(actual.sessions) AS actual_value,
            NOT isNotDistinctFrom(reference.sessions, actual.sessions) AS failed
        FROM reference
        GLOBAL FULL OUTER JOIN actual USING (data_date, client_id)
    )
SELECT
    data_date,
    countIf(reference_present) AS reference_rows,
    countIf(actual_present) AS actual_rows,
    countIf(failed) AS failed_rows,
    groupArrayIf(20)(
        concat(
            toString(data_date),
            ' key=',
            business_key,
            ': эталон=',
            if(reference_present, reference_value, 'нет ключа'),
            ', объект=',
            if(actual_present, actual_value, 'нет ключа')
        ),
        failed
    ) AS diagnostics
FROM comparison
GROUP BY data_date
ORDER BY data_date
SETTINGS join_use_nulls = 1