What's New in Oracle Data Guard?

The features and enhancements described in this preface were added to Oracle Data Guard in Oracle Database 11g.

Oracle Database 11g Release 2 ( New Features in Oracle Data Guard

The following new features are specific to SQL Apply in Oracle Data Guard 11g Release 2 (

  • Support for XMLType data stored as binary XML

  • Support for XMLType data stored in object-relational format

Support for both these storage formats requires that the primary database be running Oracle Database 11g Release 2 ( or higher with a redo compatibility setting of or higher. See "Datatype Considerations" for more information about supported data types.

New Features in Oracle Data Guard 11.2

The following sections describe the new features and enhancements that were added in Oracle Data Guard 11g Release 2 (11.2):

New 11.2 Features Common to Redo Apply and SQL Apply

  • As of Oracle Database 11g Release 2 (, Oracle Data Guard is fully integrated with Oracle Real Application Clusters One Node (Oracle RAC One Node).

  • A Data Guard configuration can now consist of a primary database and up to 30 standby databases.

  • The FAL_CLIENT database initialization parameter is no longer required.

  • The default archive destination used by the Oracle Automatic Storage Management (Oracle ASM) feature and the fast recovery area feature has changed from LOG_ARCHIVE_DEST_10 to LOG_ARCHIVE_DEST_1.

  • Redo transport compression is no longer limited to compressing redo data only when a redo gap is being resolved. When compression is enabled for a destination, all redo data sent to that destination is compressed.

  • The new ALTER SYSTEM FLUSH REDO SQL statement can be used at failover time to flush unsent redo from a mounted primary database to a standby database, thereby allowing a zero data loss failover to be performed even if the primary database is not running in a zero data loss data protection mode. See Section 8.2.2 for more information.

New 11.2 Features Specific to Redo Apply

  • You can configure apply lag tolerance in a real-time query environment by using the new STANDBY_MAX_DATA_DELAY parameter.

  • You can use the new ALTER SESSION SYNC WITH PRIMARY SQL statement to ensure that a suitably configured physical standby database is synchronized with the primary database as of the time the statement is issued.

  • The V$DATAGUARD_STATS view has been enhanced to a greater degree of accuracy in many of its columns, including apply lag and transport lag.

  • You can view a histogram of apply lag values on the physical standby. To do so, query the new V$STANDBY_EVENT_HISTOGRAM view.

  • A corrupted data block in a primary database can be automatically replaced with an uncorrupted copy of that block from a physical standby database that is operating in real-time query mode. A corrupted block in a physical standby database can also be automatically replaced with an uncorrupted copy of the block from the primary database.

See Also:

Section 9.2, "Opening a Physical Standby Database" for more information about each of these features

New 11.2 Features Specific to SQL Apply

  • Logical standby databases support tables with basic table compression, OLTP table compression, and Hybrid Columnar Compression.

    See Also:

  • Logical standby and the LogMiner utility support tables with SecureFiles LOB columns. Compression and encryption operations on SecureFiles LOB columns are also supported. (De-duplication operations and fragment-based operations are not supported.)

  • Changes made in the context of XA global transactions on an Oracle RAC primary database are replicated on a logical standby database.

  • Online redefinition performed at the primary database using the DBMS_REDEFINITION PL/SQL package is transparently replicated on a logical standby database.

  • Logical Standby supports the use of editions at the primary database, including the use of edition-based redefinition to upgrade applications with minimal downtime.

    See Also:

  • Logical standby databases support Streams Capture. This allows you to offload processing from the primary database in one-way information propagation configurations and make the logical standby the hub that propagates information to multiple databases. Streams Capture can also propagate changes that are local to the logical standby database.

New Features in Oracle Data Guard 11.1

The following sections describe the new features and enhancements that were added in Oracle Data Guard 11g Release 1 (11.1):

New 11.1 Features Common to Redo Apply and SQL Apply

  • Compression of redo traffic over the network in a Data Guard configuration

    This feature improves redo transport performance when resolving redo gaps by compressing redo before it is transmitted over the network.

    See Also:

    "COMPRESSION" attribute
  • Redo transport response time histogram

    The V$REDO_DEST_RESP_HISTOGRAM dynamic performance view contains a histogram of response times for each SYNC redo transport destination. The data in this view can be used to assist in the determination of an appropriate value for the LOG_ARCHIVE_DEST_n NET_TIMEOUT attribute.

    See Also:

    "NET_TIMEOUT" attribute
  • Faster role transitions

  • Strong authentication for redo transport network sessions

    Redo transport network sessions can now be authenticated using SSL. This provides strong authentication and makes the use of remote login password files optional in a Data Guard configuration.

  • Simplified Data Guard management interface

    The SQL statements and initialization parameters used to manage a Data Guard configuration have been simplified through the deprecation of redundant SQL clauses and initialization parameters.

    See Also:

  • Enhancements around DB_UNIQUE_NAME

    You can now find the DB_UNIQUE_NAME of the primary database from the standby database by querying the new PRIMARY_DB_UNIQUE_NAME column in the V$DATABASE view. Also, Oracle Data Guard release 11g ensures each database's DB_UNIQUE_NAME is different. After upgrading to 11g, any databases with the same DB_UNIQUE_NAME will not be able to communicate with each other.

  • Use of physical standby database for rolling upgrades

    A physical standby database can now take advantage of the rolling upgrade feature provided by a logical standby. Through the use of the new KEEP IDENTITY clause option to the SQL ALTER DATABASE RECOVER TO LOGICAL STANDBY statement, a physical standby database can be temporarily converted into a logical standby database for the rolling upgrade, and then reverted back to the original configuration of a primary database and a physical standby database when the upgrade is done.

  • Heterogeneous Data Guard Configuration

    This feature allows a mix of Linux and Windows primary and standby databases in the same Data Guard configuration.

New 11.1 Features Specific to Redo Apply

New 11.1 Features Specific to SQL Apply

  • Support Transparent Data Encryption (TDE)

    Data Guard SQL Apply can be used to provide data protection for the primary database with Transparent Data Encryption enabled. This allows a logical standby database to provide data protection for applications with advanced security requirements.

  • Dynamic setting of Data Guard SQL Apply parameters

    You can now configure specific SQL Apply parameters without requiring SQL Apply to be restarted. Using the DBMS_LOGSTDBY.APPLY_SET package, you can dynamically set initialization parameters, thus improving the manageability, uptime, and automation of a logical standby configuration.

    In addition, the APPLY_SET and APPLY_UNSET subprograms include two new parameters: LOG_AUTO_DEL_RETENTION_TARGET and EVENT_LOG_DEST.

    See Also:

    DBMS_LOGSTDBY PL/SQL package in the Oracle Database PL/SQL Packages and Types Reference
  • Enhanced Oracle RAC switchover support for logical standby databases

    When switching over to a logical standby database where either the primary database or the standby database is using Oracle RAC, the SWITCHOVER command can be used without having to shut down any instance, either at the primary or at the logical standby database.

  • Enhanced DDL handling in Oracle Data Guard SQL Apply

    SQL Apply will execute parallel DDLs in parallel (based on availability of parallel servers).

  • Use of the PL/SQL DBMS_SCHEDULER package to create Scheduler jobs on a standby database

    Scheduler Jobs can be created on a standby database using the PL/SQL DBMS_SCHEDULER package and can be associated with an appropriate database role so that they run when intended (for example, when the database is the primary, standby, or both).