Dataguard Enhancements

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SYSDG Privilege

This new privilege is used to handle Oracle Dataguard administrative duties. This privilege provides only the minimum privilege level required to administer the DataGuard standby database.

Far Sync Instance

  • An Oracle Data Guard far sync instance is a remote Oracle Data Guard destination that accepts redo from the primary database and then ships that redo to other members of the Oracle Data Guard configuration.
  • A far sync instance manages a control file, receives redo into standby redo logs (SRLs), and archives those SRLs to local archived redo logs, but that is where the similarity with standbys ends. A far sync instance does not have user data files, cannot be opened for access, cannot run redo apply, and can never function in the primary role or be converted to any type of standby database.
  • Far sync instances are part of the Oracle Active Data Guard Far Sync feature, which requires an Oracle Active Data Guard license.
  • A far sync instance consumes very little disk and processing resources, yet provides the ability to failover to a terminal destination with zero data loss, as well as offload the primary database of other types of overhead (for example, redo transport).

Cascaded Redo Transport Destinations

  • A cascaded redo transport destination receives primary database redo indirectly from a standby database rather than directly from a primary database.
  • A standby database that cascades primary database redo to one or more cascaded destinations is known as a cascading standby database.
  • Cascading offloads the overhead associated with performing redo transport from a primary database to a cascading standby database.

in 12cR1, you can now cascade in real time (without having to wait for a redo log switch) to upt to 10 destinations. This feature requires the Oracle Active Dataguard option.

Fast-Sync Mode

The Fast Sync Mode sync and noaffirm are now available for reduced latency for synchronous processing of the redo stream between the primary and standby database. (Before, only sync plus affirm were available)