pig基本语法——order by limit

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主要参考：

https://book.itxueyuan.com/3b7D/XDBe

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

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

grunt> B = order A by age DESC;

grunt> dump B;

输出结果：

(youyou,89,12.3)

(ddf,19,12.8)

(aaa,13,1.1)

(kjkj,12,12.1)

(xiaoxiao,12,12.1)

能够看到结果已经根据第二列倒叙排列了。

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主要参考：

https://book.itxueyuan.com/3b7D/BDOK

limit 主要用于限定输出数量

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

[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

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

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

grunt> B = limit A 3;

grunt> dump B;

运行结果：

(aaa,13,1.1)

(kjkj,12,12.1)

(xiaoxiao,12,12.1)