关于kettle 写入mysql 遇到一个问题：LOAD_TEMP - Unable to get database metadata from this database connection，报错大致如下：
2021/11/26 14:05:12 - LOAD_TEMP - ERROR (version 5.3.0.0-213, build 1 from 2015-02-02_12-17-08 by buildguy) : org.pentaho.di.core.exception.KettleDatabaseException: 2021/11/26 14:05:12 - LOAD_TEMP - Unable to get database metadata from this database connection 2021/11/26 14:05:12 - LOAD_TEMP - at java.lang.Thread.run (Thread.java:748) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.RunThread.run (RunThread.java:121) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.baseStep.markStop (baseStep.java:2995) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans$1.stepFinished (Trans.java:1244) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.access$600 (Trans.java:155) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.killAllNoWait (Trans.java:1727) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.baseStep.stopAll (baseStep.java:2866) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.stopAll (Trans.java:1892) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.steps.sql.ExecSQL.stopRunning (ExecSQL.java:268) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.core.database.Database.cancelQuery (Database.java:660) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.core.database.Database.getDatabasemetaData (Database.java:2718) 2021/11/26 14:05:12 - LOAD_TEMP - 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.core.database.Database.getDatabasemetaData(Database.java:2720) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.core.database.Database.cancelQuery(Database.java:660) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.steps.sql.ExecSQL.stopRunning(ExecSQL.java:268) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.stopAll(Trans.java:1892) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.baseStep.stopAll(baseStep.java:2866) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.killAllNoWait(Trans.java:1727) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans.access$600(Trans.java:155) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.Trans$1.stepFinished(Trans.java:1244) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.baseStep.markStop(baseStep.java:2995) 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.trans.step.RunThread.run(RunThread.java:121) 2021/11/26 14:05:12 - LOAD_TEMP - at java.lang.Thread.run(Thread.java:748) 2021/11/26 14:05:12 - LOAD_TEMP - Caused by: java.lang.NullPointerException 2021/11/26 14:05:12 - LOAD_TEMP - at org.pentaho.di.core.database.Database.getDatabasemetaData(Database.java:2718) 2021/11/26 14:05:12 - LOAD_TEMP - ... 10 more 2021/11/26 14:05:12 - LOAD_TEMP - ERROR (version 5.3.0.0-213, build 1 from 2015-02-02_12-17-08 by buildguy) : 错误被检测到!
大致的意思就是 不能获取到数据库中的源数据，在网上查找一番，建议是清理数据库的缓存如下：
工具 ---> 数据库 ---> 清楚缓存
但是操作下来没有用。
仔细检查了一下影射字段
在对应的表中，此字段为 is_weak_point ，hive表中的字段拼写错了。是通过获取字段直接来的。看来这个还是得仔细的核对字段名称，避免因字段拼写导致问题。将表字段改成is_weak_point 就行了。
还有一种情况也有可能出现问题。我们一般在hive 中字段类型一般用String 类型，但是业务库中字段却不是，大部分情况下是没有问题，但是遇到 数据库 中使用bit 类型，可能会出问题，一般是文件输入定义字段的时候，将String转成boolean 类型：
