orignal:http://www.cnblogs.com/subsir/articles/2631635.html
首先认识什么是分区
Hive 中的分区就是分目录，把一个大的数据集根据业务需要分割成更下的数据集。
1. 如何定义分区，创建分区
hive> create table test(name string,sex int) partitioned by (birth string, age string);
Time taken: 0.044 seconds
hive> alter table test add partition (birth=’1980′, age =’30′);
Time taken: 0.079 seconds
hive> alter table test add partition (birth=’1981′, age =’29′);
Time taken: 0.052 seconds
hive> alter table test add partition (birth=’1982′, age =’28′);
Time taken: 0.056 seconds
hive> show partitions test;
birth=1980/age =30
birth=1981/age =29
birth=1982/age =28
2. 如何删除分区
hive> alter table test drop partition (birth=’1980′,age=’30′);
3. 加载数据到指定分区
load data local inpath ‘/home/hadoop/data.log’ overwrite into table
test partition(birth=’1980-01-01′,age=’30′);
创建分区原则： 最少粒度原则
4 向partition_test的分区中插入数据：
hive> insert overwrite table partition_test partition(stat_date=’20110728′,province=’henan’) select member_id,name from partition_test_input where stat_date=’20110728′ and province=’henan’;
5 还可以同时向多个分区插入数据，0.7版本以后不存在的分区会自动创建，0.6之前的版本官方文档上说必须要预先创建好分区：
hive>
> from partition_test_input
> insert overwrite table partition_test partition (stat_date=’20110526′,province=’liaoning’)
> select member_id,name where stat_date=’20110526′ and province=’liaoning’
> insert overwrite table partition_test partition (stat_date=’20110728′,province=’sichuan’)
> select member_id,name where stat_date=’20110728′ and province=’sichuan’
> insert overwrite table partition_test partition (stat_date=’20110728′,province=’heilongjiang’)
> select member_id,name where stat_date=’20110728′ and province=’heilongjiang’;
Total MapReduce jobs = 4