说明运算符为您提供了一系列语句的逐步执行.
语法
下面给出了说明运算符的语法.
grunt> illustrate Relation_name;
示例
假设我们在HDFS中有一个文件 student_data.txt ，其中包含以下内容内容.
001,Rajiv,Reddy,9848022337,Hyderabad002,siddarth,Battacharya,9848022338,Kolkata 003,Rajesh,Khanna,9848022339,Delhi004,Preethi,Agarwal,9848022330,Pune 005,Trupthi,Mohanthy,9848022336,Bhuwaneshwar006,Archana,Mishra,9848022335,Chennai.
我们已经使用LOAD运算符将其读入关系 student ，如下所示.
grunt> student = LOAD 'hdfs://localhost:9000/pig_data/student_data.txt' USING PigStorage(',') as ( id:int, firstname:chararray, lastname:chararray, phone:chararray, city:chararray );现在，让我们说明名为student的关系，如下所示.
grunt> illustrate student;
输出
执行上述语句后，您将获得以下输出.
grunt> illustrate student;INFO org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapOnly$M ap - Aliasesbeing processed per job phase (AliasName[line,offset]): M: student[1,10] C: R:---------------------------------------------------------------------------------------------|student | id:int | firstname:chararray | lastname:chararray | phone:chararray | city:chararray |--------------------------------------------------------------------------------------------- | | 002 | siddarth | Battacharya | 9848022338 | Kolkata |---------------------------------------------------------------------------------------------