ddadmin
e29a249830
- Зачем: - объяснить студентам, почему подход MAX() + ROW_NUMBER() безопасен только при последовательном запуске. - Что: - добавлен комментарий в dim_airplanes_load.sql. - добавлен комментарий в dim_airports_load.sql. - добавлен комментарий в dim_passengers_load.sql. - добавлен комментарий в dim_routes_load.sql. - добавлен комментарий в dim_tariffs_load.sql. - Проверка: - git diff HEAD~1 sql/dds/.
97 lines
2.7 KiB
SQL
97 lines
2.7 KiB
SQL
-- Загрузка DDS dim_airplanes: SCD1 UPSERT (UPDATE изменившихся + INSERT новых).
|
|
|
|
-- Statement 1: UPDATE существующих записей (если атрибуты изменились).
|
|
WITH seats_agg AS (
|
|
SELECT
|
|
s.airplane_code,
|
|
COUNT(*)::INTEGER AS total_seats
|
|
FROM ods.seats AS s
|
|
GROUP BY s.airplane_code
|
|
),
|
|
src AS (
|
|
SELECT
|
|
a.airplane_code,
|
|
a.model,
|
|
a.range_km,
|
|
a.speed_kmh,
|
|
COALESCE(sa.total_seats, 0) AS total_seats
|
|
FROM ods.airplanes AS a
|
|
LEFT JOIN seats_agg AS sa
|
|
ON sa.airplane_code = a.airplane_code
|
|
)
|
|
UPDATE dds.dim_airplanes AS d
|
|
SET model = s.model,
|
|
range_km = s.range_km,
|
|
speed_kmh = s.speed_kmh,
|
|
total_seats = s.total_seats,
|
|
updated_at = now(),
|
|
_load_id = '{{ run_id }}',
|
|
_load_ts = now()
|
|
FROM src AS s
|
|
WHERE d.airplane_bk = s.airplane_code
|
|
AND (
|
|
d.model IS DISTINCT FROM s.model
|
|
OR d.range_km IS DISTINCT FROM s.range_km
|
|
OR d.speed_kmh IS DISTINCT FROM s.speed_kmh
|
|
OR d.total_seats IS DISTINCT FROM s.total_seats
|
|
);
|
|
|
|
-- Statement 2: INSERT новых записей (MAX(sk) + ROW_NUMBER()).
|
|
WITH seats_agg AS (
|
|
SELECT
|
|
s.airplane_code,
|
|
COUNT(*)::INTEGER AS total_seats
|
|
FROM ods.seats AS s
|
|
GROUP BY s.airplane_code
|
|
),
|
|
src AS (
|
|
SELECT
|
|
a.airplane_code,
|
|
a.model,
|
|
a.range_km,
|
|
a.speed_kmh,
|
|
COALESCE(sa.total_seats, 0) AS total_seats
|
|
FROM ods.airplanes AS a
|
|
LEFT JOIN seats_agg AS sa
|
|
ON sa.airplane_code = a.airplane_code
|
|
),
|
|
-- Учебный комментарий: Генерация SK через MAX() + ROW_NUMBER()
|
|
-- Этот подход работает безопасно только потому, что Airflow запускает
|
|
-- джобы загрузки для одной таблицы строго последовательно (concurrency=1).
|
|
-- При параллельной загрузке возникнет состояние гонки (race condition) и возможны дубли SK.
|
|
max_sk AS (
|
|
SELECT COALESCE(MAX(airplane_sk), 0) AS v
|
|
FROM dds.dim_airplanes
|
|
)
|
|
INSERT INTO dds.dim_airplanes (
|
|
airplane_sk,
|
|
airplane_bk,
|
|
model,
|
|
range_km,
|
|
speed_kmh,
|
|
total_seats,
|
|
created_at,
|
|
updated_at,
|
|
_load_id,
|
|
_load_ts
|
|
)
|
|
SELECT
|
|
(SELECT v FROM max_sk) + ROW_NUMBER() OVER (ORDER BY s.airplane_code)::INTEGER,
|
|
s.airplane_code,
|
|
s.model,
|
|
s.range_km,
|
|
s.speed_kmh,
|
|
s.total_seats,
|
|
now(),
|
|
now(),
|
|
'{{ run_id }}',
|
|
now()
|
|
FROM src AS s
|
|
WHERE NOT EXISTS (
|
|
SELECT 1
|
|
FROM dds.dim_airplanes AS d
|
|
WHERE d.airplane_bk = s.airplane_code
|
|
);
|
|
|
|
ANALYZE dds.dim_airplanes;
|