Hive 中 Array、Map、Struct 的使用

hive提供了复合数据类型：

Struct： Struct内部的数据可以通过DOT（.）来存取，例如，表中一列c的类型为STRUCT{a INT; b INT}，我们可以通过c.a来访问域a

Map（K-V对）：访问指定域可以通过["指定域名称"]进行，例如，一个Map M包含了一个group-》gid的kv对，gid的值可以通过M['group']来获取

Array：Array中的数据为相同类型，例如，假如array A中元素['a','b','c']，则A[1]的值为'b'

Struct使用

建表：

hive> create table student_test(id INT, info struct<name:STRING, age:INT>)  
    > ROW FORMAT DELIMITED FIELDS TERMINATED BY ','                         
    > COLLECTION ITEMS TERMINATED BY ':';                                   
OK  
Time taken: 0.446 seconds 

 FIELDS TERMINATED BY ：字段与字段之间的分隔符
 COLLECTION ITEMS TERMINATED BY ：一个字段各个item的分隔符 

导入数据：

$ cat test5.txt   
1,zhou:30  
2,yan:30  
3,chen:20  
4,li:80  
hive> LOAD DATA LOCAL INPATH '/home/work/data/test5.txt' INTO TABLE student_test;  
Copying data from file:/home/work/data/test5.txt  
Copying file: file:/home/work/data/test5.txt  
Loading data to table default.student_test  
OK  
Time taken: 0.35 seconds  

查询：

hive> select info.age from student_test;  
Total MapReduce jobs = 1  
......  
Total MapReduce CPU Time Spent: 490 msec  
OK  
30  
30  
20  
80  
Time taken: 21.677 seconds  

Array使用

建表：

hive> create table class_test(name string, student_id_list array<INT>)  
    > ROW FORMAT DELIMITED                                              
    > FIELDS TERMINATED BY ','                                          
    > COLLECTION ITEMS TERMINATED BY ':';                               
OK  
Time taken: 0.099 seconds  

导入数据：

$ cat test6.txt   
034,1:2:3:4  
035,5:6  
036,7:8:9:10  
hive>  LOAD DATA LOCAL INPATH '/home/work/data/test6.txt' INTO TABLE class_test ;  
Copying data from file:/home/work/data/test6.txt  
Copying file: file:/home/work/data/test6.txt  
Loading data to table default.class_test  
OK  
Time taken: 0.198 seconds  

查询：

hive> select student_id_list[3] from class_test;  
Total MapReduce jobs = 1  
......  
Total MapReduce CPU Time Spent: 480 msec  
OK  
4  
NULL  
10  
Time taken: 21.574 seconds  

Map使用

建表：

hive> create table employee(id string, perf map<string, int>)       
    > ROW FORMAT DELIMITED                                          
    > FIELDS TERMINATED BY '\t'                                
    > COLLECTION ITEMS TERMINATED BY ','                       
    > MAP KEYS TERMINATED BY ':';                                    
OK  
Time taken: 0.144 seconds  

MAP KEYS TERMINATED BY ：key value分隔符

导入数据：

$ cat test7.txt   
1       job:80,team:60,person:70  
2       job:60,team:80  
3       job:90,team:70,person:100  
hive>  LOAD DATA LOCAL INPATH '/home/work/data/test7.txt' INTO TABLE employee;

查询：

hive> select perf['person'] from employee;  
Total MapReduce jobs = 1  
......  
Total MapReduce CPU Time Spent: 460 msec  
OK  
70  
NULL  
100  
Time taken: 20.902 seconds  
hive> select perf['person'] from employee where perf['person'] is not null;     
Total MapReduce jobs = 1  
.......  
Total MapReduce CPU Time Spent: 610 msec  
OK  
70  
100  
Time taken: 21.989 seconds