pig tutorial - apache pig tutorial - Apache Pig - Illustrate Operator - pig latin - apache pig - pig hadoop
What is illustrate operator?
- The illustrate operator gives you the step-by-step execution of a sequence of statements.
- ILLUSTRATE operator is used to review how data is transformed through a sequence of Pig Latin statements.
- ILLUSTRATE command is your best friend when it comes to debugging a script.
- Prints the schema of the relation and a tuple example at standard output
Syntax:
The syntax of the illustrate operator is
grunt> illustrate Relation_name;
Example:
Assume we have a file student_data.txt in HDFS with the following content.
001, Aadhira,Arushi,9848022337, Delhi
002, Mahi,Champa,9848022338, Chennai
003, Avantika,charu,9848022339, Pune
004, Samaira,Hansa,9848022330, Kolkata
005, Abhinav,Akaash,9848022336,Bhuwaneshwar
006, Amarjeet,Aksat,9848022335, Hyderabad
And read it into a relation student using the LOAD operator as shown below.
grunt> student = LOAD 'hdfs://localhost:9000/pig_data/student_data.txt' USING PigStorage(',')
as ( id:int, firstname:chararray, lastname:chararray, phone:chararray, city:chararray );
Now, illustrate the relation named student as shown below.
grunt> illustrate student;
Output:
On executing the above statement, you will get the following output.
grunt> illustrate student;
INFO org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapOnly$M ap - Aliases
being processed per job phase (AliasName[line,offset]): M: student[1,10] C: R:
------------------------------------------------------------------------------------------------------
|student | id:int | firstname:chararray | lastname:chararray | phone:chararray | city:chararray|
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| | 002 | mahi | champa | 9848022338 | chennai |
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