Hive 分区表

Hive 分区表创建

hive> CREATE TABLE t3(id int,name string,age int) PARTITIONED BY (Year INT, Month INT) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' ;
OK
Time taken: 0.147 seconds

查看表的结构信息

hive> desc t3;
OK
id                  	int                 	                    
name                	string              	                    
age                 	int                 	                    
year                	int                 	                    
month               	int                 	                    
	 	 
# Partition Information	 	 
# col_name            	data_type           	comment             
	 	 
year                	int                 	                    
month               	int                 	                    
Time taken: 0.106 seconds, Fetched: 11 row(s)

 //添加分区,创建目录 

hive> alter table t3 add partition (year=2014, month=12);
OK
Time taken: 0.24 seconds
hive> show partitions t3;
OK
year=2014/month=12
Time taken: 0.183 seconds, Fetched: 1 row(s)

  往分区表插入数据，可以看到insert 语句会执行MR操作 ，效率非常慢，所有通常会使用load 操作.

hive>  insert into t3 partition (year=2014,month=12) (id,name,age) values(1,'ssss',12);
WARNING: Hive-on-MR is deprecated in Hive 2 and may not be available in the future versions. Consider using a different execution engine (i.e. spark, tez) or using Hive 1.X releases.
Query ID = hadoop_20180830111614_afbf7e7e-604c-49c7-bd65-dcdf4066de6c
Total jobs = 3
Launching Job 1 out of 3
Number of reduce tasks is set to 0 since there's no reduce operator

可以使用load 文件将本地文件载入到hive 表中 ，该语句会在hdfs 文件系统中自动创建目录.

hive>load data local inpath '/home/hadoop/student.txt' into table t3 partition(year=2014,month=11);

查询分区表内容:

hive> select * from t3 where year=2014 and month=11;
OK
1	tom	12	2014	11
2	hameimei	13	2014	11
3	lilei	14	2014	11
4	mayun	25	2014	11
Time taken: 0.273 seconds, Fetched: 4 row(s)

 动态分区：

首先创建一个分区表t2

    CREATE external TABLE IF NOT EXISTS t2(id int,name string,age int) 
    COMMENT 'xx' 
    PARTITIONED BY (year int, month int ) 
    ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' 
    STORED AS TEXTFILE ; 

然后使用如下SQL实现动态分区.

INSERT  OVERWRITE TABLE t2
PARTITION (year,month)
SELECT m.id,m.name,m.age,m.year,m.month
FROM t3 m;

hive> INSERT  OVERWRITE TABLE t2
    > PARTITION (year,month)
    > SELECT m.id,m.name,m.age,m.year,m.month
    > FROM t3 m;
WARNING: Hive-on-MR is deprecated in Hive 2 and may not be available in the future versions. Consider using a different execution engine (i.e. spark, tez) or using Hive 1.X releases.
Query ID = hadoop_20180830150223_1979cd0a-8433-4820-b01b-39821fec9a15
Total jobs = 3
Launching Job 1 out of 3
Number of reduce tasks is set to 0 since there's no reduce operator
Starting Job = job_1535543680929_0008, Tracking URL = http://s201:8088/proxy/application_1535543680929_0008/
Kill Command = /soft/hadoop/b

个人理解的动态分区是指不用在给表插入数据时，把分区值给写死。比如如下这样的

INSERT  OVERWRITE TABLE t2
PARTITION (year=2012,month=11)
SELECT m.id,m.name,m.age
FROM t3 m where year=2012 and month=11;