MAPREDUCE服务 MRS-Flink SQL逻辑开发规则:关联嵌套层级不超过三层

时间:2024-10-22 10:50:54

关联嵌套层级不超过三层

嵌套层级越多,回撤流的的数据量越大。

【示例】关联嵌套3层:

SELECT *
    FROM table1 WHERE column1 IN 
( 
   SELECT column1 
   FROM table2 WHERE column2 IN (
      SELECT column2
      FROM table3 WHERE column3 = 'value'
   )
)
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