Any existing processing continues until normal completion using the open log file, and any new requests will be logged to a new log file created using the old name.
Be aware that no normal transaction operation is affected if such a log message should fail, but the log message itself is affected by the transaction's failure.
因为如果日志操作失败，并没有正常的事务操作受到影响，但如果事务失败，日志消息却会受到影响。
3
Online archived logs: These are the log files that reside in the database log directory (' online ') and are no longer needed for normal database activity.