3 Replies Latest reply: Apr 21, 2014 12:13 AM by Renu-Oracle RSS

    What is real-time apply?

    user12021554

      Currently  I have setup a data guard: a primary and a physical standby  in Oracle 11.1.0.7. I have setup standby redo logs on both primary and standby. My data guard is in maximum performance mode, information is sent asynchronously from primary to standby as per following parameter:

       

      log_archive_dest_2='SERVICE=xyzsb LGWR ASYNC NOAFFIRM VALID_FOR=(ONLINE_LOGFILES

      ,PRIMARY_ROLE) DB_UNIQUE_NAME=uxyzsb REOPEN=60'

       

      1.       On standby my recovery is done using following command:

      ·         ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;

      2.      

      I see in Oracle 11  following statement as well:

      ·         ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECTION FROM SESSION;

      I am trying to understand difference  in the two recover managed standy database commands.

      I have read that USING CURRENTL LOGFILE does real-time apply.

      In 11.1, is there a difference in 1 and 2? If open standby read only mode, will command 1 not have most up to date information from the primary.

       

       

      IN 11.2, I am setting Active Data Guard. Does active  data guard require command 2, or that is done automatically by Oracle when I have setup active data guard.

        • 1. Re: What is real-time apply?
          Top.Gun

          from the doco:

          "If the real-time apply feature is enabled, apply services can apply redo data as it is received, without waiting for the current standby redo log file to be archived."

          • 2. Re: What is real-time apply?
            Top.Gun

            Also:

            "USING CURRENT LOGFILE Clause Specify USING CURRENT LOGFILE to invoke real-time apply, which recovers redo from the standby redo log files as soon as they are written, without requiring them to be archived first at the physical standby database."

            • 3. Re: What is real-time apply?
              Renu-Oracle

              Hi,

               

              "USING CURRENT LOGFILE" will enable the real-time apply feature is enabled, apply services can apply redo data as it is received, without waiting for the current standby redo log file to be archived. This results in faster switchover and failover times because the standby redo log files have been applied already to the standby database by the time the failover or switchover begins.


              IN 11.2, I am setting Active Data Guard. Does active  data guard require command 2, or that is done automatically by Oracle when I have setup active data guard.

              Ans) Yes,you need to use "USINg CURRENT LOGFILE"


              Thanks,

              Renu