我在通过hive使用mysql时遇到问题。当我这样做时：

hive> show tables;
FAILED: Error in metadata: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.metastore.HiveMetaStoreClient
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask

这是hive.log文件的部分：

2014-12-10 19:46:01,928 ERROR Datastore.Schema (Log4JLogger.java:error(125)) - Failed initialising database.
Access denied for user 'root'@'localhost' (using password: YES)
org.datanucleus.exceptions.NucleusDataStoreException: Access denied for user 'root'@'localhost' (using password: YES)

这是hive-site.xml的一节

<property>
    <name>javax.jdo.option.ConnectionUserName</name>
    <value>root</value>
</property>
<property>
    <name>javax.jdo.option.ConnectionPassword</name>
    <value></value>
</property>

但是当我在mysql中执行相同的查询时，没有问题。