1 官方地址

• Hive 0.8.0 之后引入了EXPORT and IMPORT 命令。

  1. EXPORT命令将表或分区的数据连同元数据一起导出到指定的输出位置（HDFS上）。然后可以将此输出位置移至不同的Hadoop或Hive实例，并使用IMPORT命令进行导入操作。
  2. 导出分区表时，原始数据可能位于不同的HDFS位置。还支持导出/导入分区子集的功能。
  3. 导出的元数据存储在目标目录中，数据文件存储在子目录中。
  4. EXPORT和IMPORT命令独立于所使用的源和目标Metastore DBMS工作;例如，它们可以在Derby和MySQL数据库之间使用。

2 EXPORT

• 官方语法

EXPORT TABLE tablename [PARTITION (part_column="value"[, ...])]TO 'export_target_path' [ FOR replication('eventid') ]

• 将数据导出到HDFS

 export table join_a to '/home/hadoop/data';
Copying data from file:/tmp/hadoop/b96064b0-888a-4618-a110-fc9d09d7c00b/hive_2018-01-10_08-05-04_501_1397817648848080864-1/-local-10000/_metadata
Copying file: file:/tmp/hadoop/b96064b0-888a-4618-a110-fc9d09d7c00b/hive_2018-01-10_08-05-04_501_1397817648848080864-1/-local-10000/_metadata
Copying data from hdfs://192.168.137.200:9000/user/hive/warehouse/join_a
Copying file: hdfs://192.168.137.200:9000/user/hive/warehouse/join_a/join_a.txt
OK

• 查看HDFS上的数据

[hadoop@zydatahadoop001 export]$ hdfs dfs -ls /home/hadoop/data
Found 2 items
-rwxr-xr-x   1 hadoop supergroup       1259 2018-01-10 08:05 /home/hadoop/data/_metadata
drwxr-xr-x   - hadoop supergroup          0 2018-01-10 08:05 /home/hadoop/data/data

3 IMPORT

• 官方语法

IMPORT [[EXTERNAL] TABLE new_or_original_tablename [PARTITION (part_column="value"[, ...])]]FROM 'source_path'[LOCATION 'import_target_path']

• 导入数据

hive> import from '/home/hadoop/data';
Copying data from hdfs://192.168.137.200:9000/home/hadoop/data/data
Copying file: hdfs://192.168.137.200:9000/home/hadoop/data/data/join_a.txt
Loading data to table hive1.join_a
OK
Time taken: 7.444 seconds

• 查询

hive> show tables;
OK
join_ahive> select * from join_a;
OK
1       zhangsan
2       lisi
3       wangwu1

4 其他例子

• Rename table on import:（重命名表名）

export table department to 'hdfs_exports_location/department';
import table imported_dept from 'hdfs_exports_location/department';

• Export partition and import:（导出加上分区）

export table employee partition (emp_country="in", emp_state="ka") to 'hdfs_exports_location/employee';
import from 'hdfs_exports_location/employee';

• Export table and import partition:（导入加上分区）

export table employee to 'hdfs_exports_location/employee';
import table employee partition (emp_country="us", emp_state="tn") from 'hdfs_exports_location/employee';

• Specify the import location:（指定地址）

export table department to 'hdfs_exports_location/department';
import table department from 'hdfs_exports_location/department' location 'import_target_location/department';
Import as an external table:
export table department to 'hdfs_exports_location/department';
import external table department from 'hdfs_exports_location/department';