Hive启动正常，但是执行语句出错

Hive用的是MySQL数据库，然后启动Hive的时候正常，但是执行show databases;的时候报错。

hive> show databases;
FAILED: SemanticException org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.ql.metadata.SessionHiveMetaStoreClient

经过网上查询发现是元数据的问题，启动前要初始化元数据schematool -dbType mysql -initSchema

[administrator@Master bin]$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/usr/local/hive/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop-2.10.0/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL:	 jdbc:mysql://127.0.0.1:3306/hive?createDatabaseIfNotExist=true&useSSL=true
Metastore Connection Driver :	 com.mysql.jdbc.Driver
Metastore connection User:	 administrator
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version.
Underlying cause: java.sql.SQLException : Access denied for user 'administrator'@'localhost' (using password: YES)
SQL Error code: 1045
Use --verbose for detailed stacktrace.
*** schemaTool failed ***

这里失败是因为 hive-site.xml里面关于元数据的配置没有配置对。由于hive-site.xml中配置信息非常多，可以进入hive-site.xml文件后，点击ESC，然后点击 / 输入你要查询的内容，比如/metastore database找到对应的用户名和密码的配置信息，用户名和密码是MySQL的用户名和密码。

这里输入的是MySQL的用户名。

这里输入的是MySQL的密码。

重新配置完成后再启动元数据schematool -dbType mysql -initSchema

[administrator@Master bin]$ schematool -dbType mysql -initSchema
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/usr/local/hive/lib/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/usr/local/hadoop-2.10.0/share/hadoop/common/lib/slf4j-log4j12-1.7.25.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Metastore connection URL:	 jdbc:mysql://127.0.0.1:3306/hive?createDatabaseIfNotExist=true&useSSL=true
Metastore Connection Driver :	 com.mysql.jdbc.Driver
Metastore connection User:	 root
Starting metastore schema initialization to 2.3.0
Initialization script hive-schema-2.3.0.mysql.sql
Initialization script completed
schemaTool completed

启动成功后再启动Hive然后执行hql就可以了。

参考链接：(https://ask.csdn.net/questions/679379?depth_1-utm_source=distribute.pc_relevant.none-task-ask_topic-BlogCommendFromBaidu-2&utm_source=distribute.pc_relevant.none-task-ask_topic-BlogCommendFromBaidu-2）