PigLatin 中的 JOIN 用法

Question

我想加入两个 tables/alias，假设：

Table A (People_ID, People_Name)
Table B (Location, People_ID)

以下是我的猪拉丁文输入：

join_table = JOIN A BY People_ID, B BY People_ID

但是当我输入：

describe join_table;

显示：

join_table:{A::people_id:int,A::people_name:chararray,B::people_id:int,B::location:chararray}

这正常吗？我以为结果应该是这样的：

join_table:{A::people_id:int,A::people_name:chararray,B::location:chararray}

Answer 1

是的，输出是正常的，对于你想要的输出，你必须在另一个关系中生成你的 JOINED 关系。

试试这个：

join_table = JOIN A BY People_ID, B BY People_ID

generate_joined_table = FOREACH join_table GENERATE 
A::people_id AS people_id,A::people_name AS people_name,B::location AS location;

DESCRIBE generate_joined_table;

PigLatin 中的 JOIN 用法

JOIN usages in PigLatin

apache-pig