Apache Pig – 交叉运算符

该CROSS操作符计算两个或两个以上关系的跨产品。本章举例说明如何在 Pig Latin 中使用交叉运算符。

句法

下面给出了CROSS运算符的语法。

grunt> Relation3_name = CROSS Relation1_name, Relation2_name;

例子

假设我们在HDFS的/pig_data/目录中有两个文件，customers.txt和orders.txt，如下所示。

客户.txt

1,Ramesh,32,Ahmedabad,2000.00
2,Khilan,25,Delhi,1500.00
3,kaushik,23,Kota,2000.00
4,Chaitali,25,Mumbai,6500.00
5,Hardik,27,Bhopal,8500.00
6,Komal,22,MP,4500.00
7,Muffy,24,Indore,10000.00

订单.txt

102,2009-10-08 00:00:00,3,3000
100,2009-10-08 00:00:00,3,1500
101,2009-11-20 00:00:00,2,1560
103,2008-05-20 00:00:00,4,2060

我们已经将这两个文件加载到 Pig 中，其中包含客户和订单的关系，如下所示。

grunt> customers = LOAD 'hdfs://localhost:9000/pig_data/customers.txt' USING PigStorage(',')
   as (id:int, name:chararray, age:int, address:chararray, salary:int);
  
grunt> orders = LOAD 'hdfs://localhost:9000/pig_data/orders.txt' USING PigStorage(',')
   as (oid:int, date:chararray, customer_id:int, amount:int);

现在让我们在这两个关系上使用交叉运算符来获得这两个关系的叉积，如下所示。

grunt> cross_data = CROSS customers, orders;

确认

使用DUMP运算符验证关系cross_data，如下所示。

grunt> Dump cross_data;

输出

它将产生以下输出，显示关系cross_data的内容。

(7,Muffy,24,Indore,10000,103,2008-05-20 00:00:00,4,2060) 
(7,Muffy,24,Indore,10000,101,2009-11-20 00:00:00,2,1560) 
(7,Muffy,24,Indore,10000,100,2009-10-08 00:00:00,3,1500) 
(7,Muffy,24,Indore,10000,102,2009-10-08 00:00:00,3,3000) 
(6,Komal,22,MP,4500,103,2008-05-20 00:00:00,4,2060) 
(6,Komal,22,MP,4500,101,2009-11-20 00:00:00,2,1560) 
(6,Komal,22,MP,4500,100,2009-10-08 00:00:00,3,1500) 
(6,Komal,22,MP,4500,102,2009-10-08 00:00:00,3,3000) 
(5,Hardik,27,Bhopal,8500,103,2008-05-20 00:00:00,4,2060) 
(5,Hardik,27,Bhopal,8500,101,2009-11-20 00:00:00,2,1560) 
(5,Hardik,27,Bhopal,8500,100,2009-10-08 00:00:00,3,1500) 
(5,Hardik,27,Bhopal,8500,102,2009-10-08 00:00:00,3,3000) 
(4,Chaitali,25,Mumbai,6500,103,2008-05-20 00:00:00,4,2060) 
(4,Chaitali,25,Mumbai,6500,101,2009-20 00:00:00,4,2060) 
(2,Khilan,25,Delhi,1500,101,2009-11-20 00:00:00,2,1560) 
(2,Khilan,25,Delhi,1500,100,2009-10-08 00:00:00,3,1500) 
(2,Khilan,25,Delhi,1500,102,2009-10-08 00:00:00,3,3000) 
(1,Ramesh,32,Ahmedabad,2000,103,2008-05-20 00:00:00,4,2060) 
(1,Ramesh,32,Ahmedabad,2000,101,2009-11-20 00:00:00,2,1560) 
(1,Ramesh,32,Ahmedabad,2000,100,2009-10-08 00:00:00,3,1500) 
(1,Ramesh,32,Ahmedabad,2000,102,2009-10-08 00:00:00,3,3000)-11-20 00:00:00,2,1560) 
(4,Chaitali,25,Mumbai,6500,100,2009-10-08 00:00:00,3,1500) 
(4,Chaitali,25,Mumbai,6500,102,2009-10-08 00:00:00,3,3000) 
(3,kaushik,23,Kota,2000,103,2008-05-20 00:00:00,4,2060) 
(3,kaushik,23,Kota,2000,101,2009-11-20 00:00:00,2,1560) 
(3,kaushik,23,Kota,2000,100,2009-10-08 00:00:00,3,1500) 
(3,kaushik,23,Kota,2000,102,2009-10-08 00:00:00,3,3000) 
(2,Khilan,25,Delhi,1500,103,2008-05-20 00:00:00,4,2060) 
(2,Khilan,25,Delhi,1500,101,2009-11-20 00:00:00,2,1560) 
(2,Khilan,25,Delhi,1500,100,2009-10-08 00:00:00,3,1500)
(2,Khilan,25,Delhi,1500,102,2009-10-08 00:00:00,3,3000) 
(1,Ramesh,32,Ahmedabad,2000,103,2008-05-20 00:00:00,4,2060) 
(1,Ramesh,32,Ahmedabad,2000,101,2009-11-20 00:00:00,2,1560) 
(1,Ramesh,32,Ahmedabad,2000,100,2009-10-08 00:00:00,3,1500) 
(1,Ramesh,32,Ahmedabad,2000,102,2009-10-08 00:00:00,3,3000)