Pig illustrate 运算符

#Pig illustrate 运算符
illustrate 运算符给你一步一步的执行语句序列。
**语法**
下面给出了 illustrate 运算符的语法。
```bash
grunt> illustrate Relation_name;
```
假设我们在HDFS中有一个具有以下内容的文件Student_data.txt。
```
001,Rajiv,Reddy,9848022337,Hyderabad
002,siddarth,Battacharya,9848022338,Kolkata 
003,Rajesh,Khanna,9848022339,Delhi
004,Preethi,Agarwal,9848022330,Pune 
005,Trupthi,Mohanthy,9848022336,Bhuwaneshwar
006,Archana,Mishra,9848022335,Chennai.
```
如下所示，我们已使用LOAD运算符将其读入关系student。

```bash
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，让我们说明一下名为student的关系，如下所示。
```bash
grunt> illustrate student;
```
执行上述语句后，您将获得以下输出。
```bash
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 |
--------------------------------------------------------------------------------------------- 
|        | 002    | siddarth            | Battacharya        | 9848022338      | Kolkata        |
---------------------------------------------------------------------------------------------
```

大象教程

加我微信交流吧