For direct MetaStore DB connections, we don't support retries at the client level.

已经配置好hive，mysql作为元数据的数据库。在hive中执行drop语句出错：

hive>drop table tableName;

出现下面提示信息：

FAILED: SemanticException Unable to fetch table ljz. For direct MetaStore DB connections, we don't support retries at the client level.

分析原因：mysql驱动和mysql数据库版本不匹配

解决办法：在官网：https://dev.mysql.com/downloads/connector/j/     下载相应的连接驱动包，然后解压找到我们需要的jar包

替换之前hive的jar包

$>cp mysql-connector-java-8.0.12.jar ~/soft/hive/lib $>rm ~/soft/hive/lib/mysql……old

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再次启动hive，就可以drop table 了，但是出现了下面两个警告信息：

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

原因：使用了最新的连接驱动

解决：

$>gedit ~/soft/hive/conf/hive-site.xml 修改下面选项

javax.jdo.option.ConnectionDriverName     com.mysql.cj.jdbc.Driver

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Tue Aug 07 22:13:17 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

原因：MySQL在高版本需要指明是否进行SSL连接。 
解决：在mysql连接字符串url中加入ssl=true或者false，如下所示：

$>gedit ~/soft/hive/conf/hive-site.xml 修改下面选项

javax.jdo.option.ConnectionURL     jdbc:mysql://master:3306/hive?createDatabaseIfNotExist=true&useSSL=true