Apache Pig Filter 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 Filter Example

The filter operator is used to select the required tuples from a relation based on a condition.

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 student_details.txt file.

student_details.txt

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

001,Rajiv,Reddy,21,9848022337,Hyderabad
002,siddarth,Battacharya,22,9848022338,Kolkata
003,Rajesh,Khanna,22,9848022339,Delhi
004,Preethi,Agarwal,21,9848022330,Pune
005,Trupthi,Mohanthy,23,9848022336,Bhuwaneshwar
006,Archana,Mishra,23,9848022335,Chennai
007,Komal,Nayak,24,9848022334,trivendram
008,Bharathi,Nambiayar,24,9848022333,Chennai

Step 5 - Copy student_details.txt from local file system to HDFS. In my case, the employee.txt file is stored in /home/hduser/Desktop/PIG directory.

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

Step 6 - Load Data.

student_details = LOAD 'hdfs://localhost:9000/user/hduser/pig/student_details.txt'
USING PigStorage(',')as (id:int, firstname:chararray, lastname:chararray,
age:int, phone:chararray, city:chararray);

Step 7 - Filter data by city.

filter_data = FILTER student_details BY city == 'Chennai';

Dump filter_data;

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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 Cross Example   Pig Union Example   Pig Split 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