错误使用Apache钻

Question

donutTest.json（在我的本地系统中的/ home/DEV）查询嵌入式JSON：

{ 
    "id":"0001", 
    "type":"donut", 
    "name":"Cake", 

    "batter":{ 
      "id":"1001", 
      "type":"Regular" 
      }, 

    "topping":[ 
      { "id":"5001", "type":"None"}, 
      { "id":"5002", "type":"Glazed"} 
      ] 
} 

此查询工作正常。

select topping[0].id as topping_id, topping[3].type as topping_type from dfs.`/home/dev/donutTest.json`; 

但当我：

select batter.id as batter_id, batter.type as batter_type from dfs.`/home/dev/donutTest.json`; 

它的示值误差。

表 '连击' 未找到

topping[0]和batter都被嵌入文档还是错误。

Answer 1

尝试使用表别名，然后在select语句中引用它。

select donut.batter.id as batter_id, donut.batter.type as batter_type from dfs.`/home/dev/donutTest.json` as donut; 

这种方式Drill具有对实际表别名的引用，然后引用下面的嵌套结构。