Question

我想出了以下查询来计算每天的库存余额。查询工作并给出了预期的结果，但是在事务表的子集上运行大约需要200秒，大约有2个行。作为bigquery的新手，我想知道是否有更好/更有效的方法来做到这一点？

下面是包含一些示例数据的代码。提前感谢任何想法或提示。

#### Generate a continuous date range
WITH days AS 
  (
  SELECT day
  FROM UNNEST(
    GENERATE_DATE_ARRAY(DATE('2011-01-01'), CURRENT_DATE(), INTERVAL 1 DAY)) AS day
  ),

#### Transactional information of inventory movements. Simple example
movements AS  
  (
  SELECT 1 AS ItemID
        ,1 AS Location
        ,DATE('2017-12-01') AS TransactionDate
        ,0 AS Quantity
        UNION ALL SELECT 1, 1, DATE('2017-12-03'), 10
        UNION ALL SELECT 1, 1, DATE('2017-12-06'), 100
        UNION ALL SELECT 1, 1, DATE('2017-12-12'), 1000
  ),  

#### Calculate cumulative sum for each item and location based on the transaction date
cumsum AS
  (
  SELECT ItemID
        ,TransactionDate
        ,Location
        ,SUM(Quantity) OVER (PARTITION BY ItemID, Location ORDER BY TransactionDate ROWS UNBOUNDED PRECEDING) as cumulative_quantity
  FROM movements
  ),  

#### Cross join with the date range to backfill cumulative values for each day
#### This will return multiple lines for a day when there are multiple transaction date balances
cross_sum AS
  (
  SELECT m.ItemID
        ,m.Location
        ,d.day
        ,m.TransactionDate
        ,m.cumulative_quantity
  FROM days d
  CROSS JOIN cumsum m
  WHERE m.TransactionDate <= d.day
  ),

#### Get just one line per day, based on the latest transaction date
filtered AS
  (
  SELECT ItemID
      ,Location
      ,CAST (day AS datetime) AS BalanceDate
      ,ARRAY_AGG(cumulative_quantity ORDER BY TransactionDate DESC LIMIT 1) AS InventoryBalance
  FROM cross_sum
  GROUP BY 1,2,3
  )

#### Final result, flattened out
SELECT ItemID
      ,Location
      ,BalanceDate
      ,(SELECT SUM(InventoryBalance) FROM UNNEST(InventoryBalance) AS InventoryBalance) AS InventoryBalance
FROM filtered
ORDER BY 1,2,3

Answer 1

我想知道是否有更好/更有效的方法来做到这一点？

以下是BigQuery Standard SQL

正如您所看到的那样：days，cumsum和cross_sum被修改/优化，剩下的就被淘汰了。它具有更高的效率，但需要在实际数据上进行测试 - 因此您应该尝试查看它是否

#standardSQL
#### Transactional information of inventory movements. Simple example
WITH movements AS (
  SELECT 1 AS ItemID, 1 AS Location, DATE('2017-12-01') AS TransactionDate, 0 AS Quantity UNION ALL 
  SELECT 1, 1, DATE('2017-12-03'), 10 UNION ALL 
  SELECT 1, 1, DATE('2017-12-06'), 100 UNION ALL 
  SELECT 1, 1, DATE('2017-12-12'), 1000
), days AS (
  SELECT day, ItemID, Location
  FROM UNNEST(GENERATE_DATE_ARRAY((SELECT MIN(TransactionDate) AS d FROM movements), CURRENT_DATE(), INTERVAL 1 DAY)) AS day
  CROSS JOIN (SELECT DISTINCT ItemID, Location FROM movements)
), cumsum AS (
  SELECT ItemID
        ,TransactionDate
        ,Location
        ,LEAD(TransactionDate) OVER(PARTITION BY ItemID, Location ORDER BY TransactionDate) AS NextTransactionDate
        ,SUM(Quantity) OVER(PARTITION BY ItemID, Location ORDER BY TransactionDate ROWS UNBOUNDED PRECEDING) AS cumulative_quantity
  FROM movements
), cross_sum AS (
  SELECT d.ItemID
        ,d.Location
        ,d.day AS BalanceDate
        ,m.cumulative_quantity
  FROM days d
  JOIN cumsum m
  ON d.day >= IFNULL(m.TransactionDate, d.day) 
  AND d.day < IFNULL(m.NextTransactionDate, CURRENT_DATE())
)
SELECT ItemID
  ,Location
  ,BalanceDate
  ,cumulative_quantity
FROM cross_sum
ORDER BY 1,2,3

结果是

ItemID  Location    BalanceDate    cumulative_quantity   
1         1         2017-12-01     0     
1         1         2017-12-02     0     
1         1         2017-12-03     10    
1         1         2017-12-04     10    
1         1         2017-12-05     10    
1         1         2017-12-06     110   
1         1         2017-12-07     110   
1         1         2017-12-08     110   
1         1         2017-12-09     110   
1         1         2017-12-10     110   
1         1         2017-12-11     110   
1         1         2017-12-12     1110  
1         1         2017-12-13     1110  
1         1         2017-12-14     1110  
1         1         2017-12-15     1110

是否可以改善对bigquery的每日库存余额计算

1 个答案: