【大数据学习--hive】hive中执行select * from tablename 报错问题。

在虚拟机中搭建hive之后，创建了表，在执行select * from tablename的时候报错，具体报错信息如下：

hive> select * from hive_01;
FAILED: SemanticException Unable to determine if hdfs://master:9000/user/hive/warehouse/hive_1.db/hive_01 is encrypted: java.lang.IllegalArgumentException: java.net.UnknownHostException: master

报错的大致意思是：hive_1库被锁，后面的提示是未知的主机名：master；根据报错提示：说明创建hive_1库的时候默认保存路径是

hdfs://master:9000/user/hive/warehouse/hive_1.db/hive_01,但是实际上现在找不到这个路径，即：未知的主机名：master，这才像想起来namenode之前设置的主机名为master，后来改了主机名为namenode，由于hive的元数据已经设置保存在mysql中，因此需要修改mysql中记录的默认路径即可，此处主要修改两张表，分别如下：

mysql> select * from DBS;
+-------+-----------------------+--------------------------------------------------+---------+------------+------------+-----------+
| DB_ID | DESC                  | DB_LOCATION_URI                                  | NAME    | OWNER_NAME | OWNER_TYPE | CTLG_NAME |
+-------+-----------------------+--------------------------------------------------+---------+------------+------------+-----------+
|     1 | Default Hive database | hdfs://master:9000/user/hive/warehouse           | default | public     | ROLE       | hive      |
|     2 | NULL                  | hdfs://master:9000/user/hive/warehouse/hive_1.db | hive_1  | root       | USER       | hive      |
+-------+-----------------------+--------------------------------------------------+---------+------------+------------+-----------+

mysql> select * from SDS;
+-------+-------+------------------------------------------+---------------+---------------------------+----------------------------------------------------------+-------------+------------------------------------------------------------+----------+
| SD_ID | CD_ID | INPUT_FORMAT                             | IS_COMPRESSED | IS_STOREDASSUBDIRECTORIES | LOCATION                                                 | NUM_BUCKETS | OUTPUT_FORMAT                                              | SERDE_ID |
+-------+-------+------------------------------------------+---------------+---------------------------+----------------------------------------------------------+-------------+------------------------------------------------------------+----------+
|     1 |     1 | org.apache.hadoop.mapred.TextInputFormat |               |                           | hdfs://master:9000/user/hive/warehouse/hive_1.db/hive_01 |          -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat |        1 |
+-------+-------+------------------------------------------+---------------+---------------------------+----------------------------------------------------------+-------------+------------------------------------------------------------+----------+
1 row in set (0.00 sec)

修改DBS表的DB_LOCATION_URI 的值

mysql> update DBS set DB_LOCATION_URI=REPLACE(‘DB_LOCATION_URI‘,‘hdfs://master:9000/user/hive/warehouse‘,‘hdfs://namenode:9000/user/hive/warehouse‘)      
    -> ;
Query OK, 2 rows affected (0.05 sec)
Rows matched: 2  Changed: 2  Warnings: 0

mysql> select * from DBS;   +-------+-----------------------+-----------------+---------+------------+------------+-----------+
| DB_ID | DESC                  | DB_LOCATION_URI | NAME    | OWNER_NAME | OWNER_TYPE | CTLG_NAME |
+-------+-----------------------+-----------------+---------+------------+------------+-----------+
|     1 | Default Hive database | DB_LOCATION_URI | default | public     | ROLE       | hive      |
|     2 | NULL                  | DB_LOCATION_URI | hive_1  | root       | USER       | hive      |
+-------+-----------------------+-----------------+---------+------------+------------+-----------+
2 rows in set (0.00 sec)

修改SDS表中LOCATION字段的值

mysql> update SDS set LOCATION=REPLACE(LOCATION,‘hdfs://master:9000/user/hive/warehouse/hive_1.db/hive_01‘,‘hdfs://namenode:9000/user/hive/warehouse/hive_1.db/hive_01‘);     
Query OK, 1 row affected (0.08 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from SDS;    +-------+-------+------------------------------------------+---------------+---------------------------+------------------------------------------------------------+-------------+------------------------------------------------------------+----------+
| SD_ID | CD_ID | INPUT_FORMAT                             | IS_COMPRESSED | IS_STOREDASSUBDIRECTORIES | LOCATION                                                   | NUM_BUCKETS | OUTPUT_FORMAT                                              | SERDE_ID |
+-------+-------+------------------------------------------+---------------+---------------------------+------------------------------------------------------------+-------------+------------------------------------------------------------+----------+
|     1 |     1 | org.apache.hadoop.mapred.TextInputFormat |               |                           | hdfs://namenode:9000/user/hive/warehouse/hive_1.db/hive_01 |          -1 | org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat |        1 |
+-------+-------+------------------------------------------+---------------+---------------------------+------------------------------------------------------------+-------------+------------------------------------------------------------+----------+
1 row in set (0.01 sec)

修改完毕，重启mysql服务后，在hive中执行查询操作：

hive> select * from hive_01;
OK
Time taken: 2.329 seconds
hive>

OK......一切正常。

此例可适用于修改了HDFS默认端口，主机名等情况。