ITPub博客

首页 > Linux操作系统 > Linux操作系统 > Applying Redo Data to Physical Standby Databases

Applying Redo Data to Physical Standby Databases

原创 Linux操作系统 作者:todayboy 时间:2012-05-31 20:54:39 0 删除 编辑

6.3 Applying Redo Data to Physical Standby Databases

By default, the redo data is applied from archived redo log files. When performing Redo Apply, a physical standby database can use the real-time apply feature to apply redo directly from the standby redo log files as they are being written by the RFS process. Note that log apply services cannot apply redo data to a physical standby database when it is opened in read-only mode.

This section contains the following topics:

6.3.1 Starting Redo Apply

To start log apply services on a physical standby database, ensure the physical standby database is started and mounted and then start Redo Apply using the SQL ALTER DATABASE RECOVER MANAGED STANDBY DATABASE statement.

You can specify that Redo Apply runs as a foreground session or as a background process, and enable it with real-time apply.

  • To start Redo Apply in the foreground, issue the following SQL statement:

    SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE;
    

    If you start a foreground session, control is not returned to the command prompt until recovery is canceled by another session.

  • To start Redo Apply in the background, include the DISCONNECT keyword on the SQL statement. For example:

    SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;
    

    This statement starts a detached server process and immediately returns control to the user. While the managed recovery process is performing recovery in the background, the foreground process that issued the RECOVER statement can continue performing other tasks. This does not disconnect the current SQL session.

  • To start real-time apply, include the USING CURRENT LOGFILE clause on the SQL statement. For example:

    SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE;
    

6.3.2 Stopping Redo Apply

To stop Redo Apply, issue the following SQL statement in another window:

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/7583803/viewspace-731611/,如需转载,请注明出处,否则将追究法律责任。

请登录后发表评论 登录
全部评论

注册时间:2009-02-24

  • 博文量
    75
  • 访问量
    242711