访问 BigQuery RECORD - 在 Tableau 中重复

Question

我有一个 BigQuery 表，其中有一列 RECORD 类型和模式 REPEATED。我必须在 Tableau 中查询和使用这个表。在 BigQuery 中使用 UNNEST 或 FLATTEN 正在执行影响性能的表的 CROSS JOIN。有没有其他方法可以在 Tableau 中使用此表而不展平它。已在下面发布了表架构图片链接。

[表的架构] https://i.stack.imgur.com/T4jHg.png

Answer 1

还有其他方法可以使用...吗？

您不应该仅仅因为 UNNEST “确实” CROSS JOIN 而害怕它
诀窍是，即使它是交叉连接，但它只是行内的交叉连接，并且对表中的所有行都是全局的。同时，总有办法做不同的事情
因此，下面的示例 1 – 展示了使用 UNNEST 的虚拟示例
然后示例 2 – 展示了如何在不使用 UNNEST 而是使用 SQL UDF 的情况下执行相同操作
您尚未提供有关您的案例的具体信息，因此以下内容足够通用以显示“其他”方式

与Flattening via UNNEST

#standardSQL
WITH yourTable AS (
  SELECT 1 AS id, ARRAY<STRUCT<details INT64, flag STRING, value STRING, description STRING>>
    [(1,'y','a','xxx'),(2,'n','b','yyy'),(3,'y','c','zzz'),(4,'n','d','vvv')] AS type UNION ALL
  SELECT 2 AS id, ARRAY<STRUCT<details INT64, flag STRING, value STRING, description STRING>>
    [(11,'t','c','xxx'),(21,'n','a','yyy'),(31,'y','c','zzz'),(41,'f','d','vvv')] AS type
)
SELECT id, SUM(t.details) AS details
FROM yourTable, UNNEST(type) AS t
WHERE t.flag = 'y'
GROUP BY id

与SQL UDF

#standardSQL
CREATE TEMP FUNCTION do_something (
  type  ARRAY<STRUCT<details INT64, flag STRING, value STRING, description STRING>>
)
RETURNS INT64 AS ((
  SELECT SUM(t.details) AS details
  FROM UNNEST(type) AS t
  WHERE t.flag = 'y'
));

WITH yourTable AS (
  SELECT 1 AS id, ARRAY<STRUCT<details INT64, flag STRING, value STRING, description STRING>>
    [(1,'y','a','xxx'),(2,'n','b','yyy'),(3,'y','c','zzz'),(4,'n','d','vvv')] AS type UNION ALL
  SELECT 2 AS id, ARRAY<STRUCT<details INT64, flag STRING, value STRING, description STRING>>
    [(11,'t','c','xxx'),(21,'n','a','yyy'),(31,'y','c','zzz'),(41,'f','d','vvv')] AS type
)
SELECT id, do_something(type) AS details
FROM yourTable