【背景说明】

之前hadoop有问题，把hadoop和MySQL删了重装，hive没有动，然后启hive的metastore服务的时候，显示找不到metastore数据库

【报错】

Caused by: java.lang.reflect.InvocationTargetExceptionat sun.reflect.GeneratedConstructorAccessor74.newInstance(Unknown Source)at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)at java.lang.reflect.Constructor.newInstance(Constructor.java:423)at org.datanucleus.plugin.NonManagedPluginRegistry.createExecutableExtension(NonManagedPluginRegistry.java:606)at org.datanucleus.plugin.PluginManager.createExecutableExtension(PluginManager.java:330)at org.datanucleus.store.AbstractStoreManager.registerConnectionFactory(AbstractStoreManager.java:203)at org.datanucleus.store.AbstractStoreManager.<init>(AbstractStoreManager.java:162)at org.datanucleus.store.rdbms.RDBMSStoreManager.<init>(RDBMSStoreManager.java:285)at sun.reflect.GeneratedConstructorAccessor73.newInstance(Unknown Source)at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)at java.lang.reflect.Constructor.newInstance(Constructor.java:423)at org.datanucleus.plugin.NonManagedPluginRegistry.createExecutableExtension(NonManagedPluginRegistry.java:606)at org.datanucleus.plugin.PluginManager.createExecutableExtension(PluginManager.java:301)at org.datanucleus.NucleusContextHelper.createStoreManagerForProperties(NucleusContextHelper.java:133)at org.datanucleus.PersistenceNucleusContextImpl.initialise(PersistenceNucleusContextImpl.java:422)at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.freezeConfiguration(JDOPersistenceManagerFactory.java:817)... 43 more
Caused by: org.datanucleus.exceptions.NucleusException: Attempt to invoke the "HikariCP" plugin to create a ConnectionPool gave an error : Failed to initialize pool: Unknown database 'metastore'at org.datanucleus.store.rdbms.ConnectionFactoryImpl.generateDataSources(ConnectionFactoryImpl.java:232)at org.datanucleus.store.rdbms.ConnectionFactoryImpl.initialiseDataSources(ConnectionFactoryImpl.java:117)at org.datanucleus.store.rdbms.ConnectionFactoryImpl.<init>(ConnectionFactoryImpl.java:82)... 59 more
Caused by: com.zaxxer.hikari.pool.HikariPool$PoolInitializationException: Failed to initialize pool: Unknown database 'metastore'at com.zaxxer.hikari.pool.HikariPool.throwPoolInitializationException(HikariPool.java:544)at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:536)at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:112)at com.zaxxer.hikari.HikariDataSource.<init>(HikariDataSource.java:72)at org.datanucleus.store.rdbms.connectionpool.HikariCPConnectionPoolFactory.createConnectionPool(HikariCPConnectionPoolFactory.java:176)at org.datanucleus.store.rdbms.ConnectionFactoryImpl.generateDataSources(ConnectionFactoryImpl.java:213)... 61 more
Caused by: java.sql.SQLSyntaxErrorException: Unknown database 'metastore'at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828)at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448)at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241)at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:95)at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:101)at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:356)at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:199)at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:444)at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:515)

【原因】

我真是个傻子，重装以后要在MySQL初始化metastore元数据库

【解决】

3.3.1初始化元数据库
1）登陆MySQL。
[atguigu@hadoop102 conf]$ mysql -uroot -p000000
2）新建Hive元数据库。
mysql> create database metastore;
3）初始化Hive元数据库。
[atguigu@hadoop102 conf]$ schematool -initSchema -dbType mysql -verbose
4）修改元数据库字符集。
Hive元数据库的字符集默认为Latin1，由于其不支持中文字符，所以建表语句中如果包含中文注释，会出现乱码现象。如需解决乱码问题，须做以下修改。
修改Hive元数据库中存储注释的字段的字符集为utf-8。
（1）字段注释。
mysql> use metastore;
mysql> alter table COLUMNS_V2 modify column COMMENT varchar(256) character set utf8;
（2）表注释。
mysql> alter table TABLE_PARAMS modify column PARAM_VALUE mediumtext character set utf8;
5）退出mysql。
mysql> quit;
3.3.2启动Hive客户端
1）启动Hive客户端。
[atguigu@hadoop102 hive]$ hive
2）查看一下数据库。
hive (default)> show databases;
OK
database_name
default
Time taken: 0.955 seconds, Fetched: 1 row(s)

成功~