Creates the online redo log files if they do not currently exist.
联机日志损坏，不能做完整修复时，用的。
Changing the size and number of the online redo log files is sometimes done to tune the database.
改变在线重做日志文件大小和数量有时是优化数据库。
Redo Logfile Sizing Advisor - This feature recommends the optimal size of redo log files in order to avoid excessive disk I/Os due to frequent checkpointing.
Redo Logfile SizingAdvisor ——此特性推荐重做日志文件的最佳大小，从而避免因频繁出现的检查点而导致过多的磁盘I/O。
Whenever you add an online redo log file to the primary database, you should add corresponding online and standby redo log files to the standby database.
无论何时，你在主库添加在线重做日志文件，你应该在备库添加相应的在线重做日志和备用重做日志文件。
The maximum protection and maximum availability modes require that standby redo log files are configured on at least one standby database in the configuration.
最大保护和最大可用性模式需要备重做日志文件配置在配置中的至少一个备数据库上。
Checkpoint (CKPt) - Synchronizes the headers of data files and control files with the current redo log and checkpoint Numbers.
检查点(CKPt)——将数据文件头和控制文件头与当前重做日志和检查点数同步。
Log Writer (LGWr) - Writes entries from log buffer to redo the log files.
日志读写器(LGWr)——从日志缓冲区写入项目，以便重做日志文件。
When a physical standby database is open, redo data from the primary database is received by the standby database, but the log files are not applied.
当物理备库是打开时，来自主库的重做数据被备库接收，但是不会被应用。
When a physical standby database is open, redo data from the primary database is received by the standby database, but the log files are not applied.
当物理备库是打开时，来自主库的重做数据被备库接收，但是不会被应用。
应用推荐