Apache Pig cross example

posted on Nov 20th, 2016

Apache Pig

Apache Pig is a high-level platform for creating programs that run on Apache Hadoop. The language for this platform is called Pig Latin. Pig can execute its Hadoop jobs in MapReduce, Apache Tez, or Apache Spark. Pig Latin abstracts the programming from the Java MapReduce idiom into a notation which makes MapReduce programming high level, similar to that of SQL for RDBMSs. Pig Latin can be extended using User Defined Functions (UDFs) which the user can write in Java, Python, JavaScript, Ruby or Groovy and then call directly from the language.

Pre Requirements

1) A machine with Ubuntu 14.04 LTS operating system

2) Apache Hadoop 2.6.4 pre installed (How to install Hadoop on Ubuntu 14.04)

3) Apache Pig pre installed (How to install Pig on Ubuntu 14.04)

Pig Cross Example

The cross operator computes the cross-product of two or more relations. This chapter explains with example how to use the cross operator in Pig Latin.

Step 1 - Change the directory to /usr/local/pig/bin

$ cd /usr/local/pig/bin

Step 2 - Enter into grunt shell in MapReduce mode.

$ ./pig -x mapreduce

Step 3 - Create a customers.txt file.

customers.txt

Step 4 - Add these following lines to customers.txt file.

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

Step 5 - Create a orders.txt file.

orders.txt

Step 6 - Add these following lines to orders.txt file.

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

Step 7 - Copy customers.txt and orders.txt from local file system to HDFS. In my case, the customers.txt and orders.txt file are stored in /home/hduser/Desktop/PIG/ directory.

$ hdfs dfs -copyFromLocal /home/hduser/Desktop/PIG/customers.txt /user/hduser/pig/
$ hdfs dfs -copyFromLocal /home/hduser/Desktop/PIG/orders.txt /user/hduser/pig/

Step 8 - Load customers data.

customers = LOAD 'hdfs://localhost:9000/user/hduser/pig/customers.txt' USING
PigStorage(',')as (id:int, name:chararray, age:int, address:chararray,
salary:int);

Step 9 - Load orders data.

orders = LOAD 'hdfs://localhost:9000/user/hduser/pig/orders.txt' USING
PigStorage(',')as (oid:int, date:chararray, customer_id:int, amount:int);

Step 10 - Cross data.

cross_data = CROSS customers, orders;

Dump cross_data;

Please share this blog post and follow me for latest updates on

facebook             google+             twitter             feedburner

Previous Post                                                                                          Next Post

Labels : Pig Installation   Pig Execution Mechanism   Pig GRUNT Shell Usage   Pig Load and Store Operations   Pig Diagnostic Operators   Pig Group Example   Pig Join Example   Pig Union Example   Pig Split Example   Pig Filter Example   Pig Distinct Example   Pig Foreach Example   Pig OrderBy Example   Limit Example   Pig Eval Functions Example   Pig BagToString Example   Pig Concat Example   Pig Tokenize Example   Pig UDF's Java Example   Pig SCRIPT