连接MySql报错Unable to load authentication plugin ‘caching_sha2_password’
错误的原因是由于MySQL8.0之后的加密规则为caching_sha2_password，而在此之前的加密规则为mysql_native_password。解决方法：
mysql -u root -p
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '密码'; // USER是表名java.math.BigInteger cannot be cast to java.lang.Long
报错：
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version. Underlying cause: java.sql.SQLException : java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long解决
原来项目的jar包版本是5.1.27会报错，换成5.1.46就ok了：mysql-connector-java-5.1.46，版本问题！
Unknown system variable ‘query_cache_size’
解决参考：版本问题
