pig基本语法——union和split

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union用于连接结构相同的表，split可以根据条件拆分表。

1、基础数据：

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[root@cdh1 data]# cat demodata

xiaoxiao,12,12.1f

aaa,13,1.1f

kjkj,12,12.1f

ddf,19,12.8f

youyou,89,12.3f

==============================================

2、使用union

grunt> A = load '/root/xytest/pig/data/demodata' using PigStorage(',') as (name:chararray,age:int,gpa:float);

grunt> B = load '/root/xytest/pig/data/demodata' using PigStorage(',') as (name:chararray,age:int,gpa:float);

grunt> C = union A,B;

grunt> dump C;

输出结果：

(xiaoxiao,12,12.1)

(aaa,13,1.1)

(kjkj,12,12.1)

(ddf,19,12.8)

(youyou,89,12.3)

(xiaoxiao,12,12.1)

(aaa,13,1.1)

(kjkj,12,12.1)

(ddf,19,12.8)

(youyou,89,12.3)

3、使用split

grunt> A = load '/root/xytest/pig/data/demodata' using PigStorage(',') as (name:chararray,age:int,gpa:float);

grunt> split A into D if age < 18,E if age >=18;

grunt> dump D;

输出结果：

(xiaoxiao,12,12.1)

(aaa,13,1.1)

(kjkj,12,12.1)

grunt> dump E;

输出结果：

(ddf,19,12.8)

(youyou,89,12.3)