ORA-01609: log string is the current log for thread string – cannot drop members
Cause: A member of the current log for a thread cannot be dropped.
Action: If the thread is opened, request a log switch by the instance that is using it. If it is not open, disable the thread, manually archive the log, or clear it.
ORA-01609错误是由于在当前日志期间尝试删除已在工作的日志组时发生的，而其中的某个成员正在使用时导致的。
ORA-01609: log string is the current log for thread string – cannot drop members
Cause: The database attempted to drop a member from the redo log group when it was the current log for a thread. This operation is not allowed.
Action: Check for any open database processes that could be using the member of the redo log group and make sure that it is no longer used. Then drop the member with the ALTER DATABASE DROP LOGFILE command.
ORA-01609错误常常会发生在一个应用程序或会话正在处理日志组中某个成员，而另一个会话尝试删除该组成员时产生。
对于ORA-01609错误，可以通过以下步骤来处理：
1、检查是否有任何正在使用日志组成员（运行v$session表）。
2、确认这个成员已不再使用，可以使用alter database drop logfile命令来删除它。