Oracle-Specific Considerations

These general issues and considerations are specific to using Replication Agent with the Oracle data server.

• Unsupported Oracle Software Features
  Review the Oracle features that are not supported by Replication Agent.
• Unsupported Oracle Datatypes, Data, and Structures
  Review the Oracle datatypes that are not supported by Replication Agent.
• Supported Oracle Datatypes, Data, and Structures
  Replication Agent supports the replication of encrypted data, compressed data, and SecureFiles.
• Replication Agent Connectivity
  Replication Agent for Oracle uses JDBC™ for communications with all replication system components.
• Replication Agent Permissions
  Replication Agent for Oracle uses the pds_username to connect to Oracle and must have certain Oracle permissions.
• Multiple Replication Agents
  Multiple Replication Agent instances allow transactions to be replicated in parallel along multiple independent paths, increasing replication throughput and performance, and reducing resource contention.
• High Availability
  A primary data server may employ a high-availability solution, such as failover clustering, to minimize downtime in the event of hardware or software failure.
• Redo and Archive Log Setup
  By default, you can access both online and archive logs. You can configure Replication Agent to access only the online logs, but doing so requires you to turn Oracle automatic archiving off and requires Replication Agent to issue manual archive log commands to Oracle.
• Supplemental Logging
  Enable supplemental logging and supplemental logging of primary key data and index columns.
• DDL Replication
  Replication of data definition language (DDL) commands is supported, but only to Oracle databases. You cannot replicate DDL commands from Oracle to non-Oracle replicate databases.
• Character Case of Database Object Names
  Database object names must be delivered to the primary Replication Server in the same format as specified in replication definitions; otherwise, replication fails. For example, if a replication definition specifies a table name in all lowercase, then that table name must appear in all lowercase when it is sent to the primary Replication Server by the Replication Agent.
• Format of Origin Queue ID
  Each record in the transaction log is identified by an origin queue ID that consists of 64 hexadecimal characters (32 bytes). The format of the origin queue ID is determined by the Replication Agent instance and varies according to the primary database type.
• LTL Origin Commit Time Granularity
  For Oracle, the precision of the origin commit time does not include milliseconds.
• Replication Server and RSSD Scripts
  Replication Agent provides supplemental scripts to support additional Replication Server user-defined datatypes for Oracle datatypes and the replication of DDL commands.
• Oracle Datatype Compatibility
  Replication Agent for Oracle processes Oracle transactions and passes data to the primary Replication Server. In turn, the primary Replication Server uses the datatype formats specified in the replication definition to receive the data from Replication Agent for Oracle.
• Oracle Datatype Restrictions
  Replication Server and Replication Agent impose some constraints on the Oracle NUMBER datatype.
• Oracle Large Object (LOB) Support
  Oracle LOB data can exist in several formats in Oracle.
• Oracle User-Defined Types
  User-defined datatypes (UDDs) use Oracle built-in datatypes and other user-defined datatypes as building blocks that model the structure and behavior of data in applications.
• Sequence Marking and Unmarking
  Support for Oracle sequence replication is supported only for replication to Oracle. No support is provided for replicating a sequence value to a non-Oracle replicate database.
• Sequence Replication Enabling and Disabling
  To temporarily suspend replication of a sequence, use pdb_setrepseq to disable replication for the marked sequence. When you are ready to resume replication of the marked sequence, use pdb_setrepseq again to enable replication.
• Setting Up Replication Agent and Oracle on Different Machines
  Run Replication Agent and the primary data server on different machines.
• Real Application Clusters (RAC)
  Replication Agent for Oracle provides support for Oracle 10g and 11g RAC environments. When a Replication Agent for Oracle instance is initialized, the Oracle database is queried to determine how many nodes are supported by the cluster. Based on this information, Replication Agent automatically configures itself to process the redo log information from all nodes.
• Automatic Storage Management
  Replication Agent for Oracle supports the use of the Oracle Automatic Storage Management (ASM) feature. ASM provides file system and volume management support for an Oracle database environment. ASM can be used in both Real Application Cluster (RAC) and non-RAC environments.
• Replication Server set autocorrection Command
  The Replication Server set autocorrection command prevents failures that would otherwise be caused by missing or duplicate rows in a replicated table.
• Partitioned Tables
  Replication Agent supports Oracle partitioning functionality.
• Materialized Views
  A materialized view is a stored view query result.
• Index-Organized Tables
  Replication Agent can replicate DML for Oracle index-organized tables (IOTs).
• Replicate Database Trigger Execution Control
  Trigger execution in a replication system can cause problems when both the transaction that caused a trigger to fire and the transactions that resulted from the trigger are replicated.
• Alteration of Replication Definitions from the Primary Data Server
  You can alter replication definitions from the primary data server.
• Oracle Data Guard
  Data Guard is a disaster-protection architecture consisting of a primary Oracle database and one or more standby Oracle databases to which the primary database copies its data. These standby copies can be used in the event that the primary Oracle database fails. Replication Agent supports replication of data from an Oracle database system that uses Data Guard.
• Database Resynchronization
  You can avoid having to quiesce the primary database when you initialize Replication Agent for Oracle if your replication system is configured for database resynchronization.
• Oracle Transaction and Operation Troubleshooting
  The ra_dumptran and ra_helpop commands return information for use in troubleshooting a specified Oracle database transaction or database operation, respectively.
• Stored Procedure Replication with BOOLEAN Arguments
  Learn how to replicate Oracle stored procedures with arguments of boolean type.
• Oracle Warm Standby
  Using Replication Server, you can create and maintain a warm standby environment for an Oracle database.
• Oracle Flashback
  Replication Agent can replicate Oracle Flashback operations performed at the table level and the transaction level.
• XMLTYPE Data Replication
  When an Oracle table is created with an XMLTYPE column but without any XML schema specification, a hidden CLOB column is automatically created to store the XML data. The XMLTYPE column becomes a virtual column for the hidden CLOB column. In the corresponding Oracle base table, the hidden column immediately follows the XMLTYPE column that it represents and is named SYS_NCnnnnn$, where nnnnn represents the position of the hidden column in the base table.
• Oracle 11g Release 2
  All of the functionality that Replication Agent supports for Oracle Database 11g Release 1 is also supported by Replication Agent for Oracle Database 11g Release 2. Replication Agent also supports some functionality introduced by Oracle Database 11g Release 2.
• Oracle 9i
  Replication Agent supports Oracle 9i when Oracle 10g or 11g is running in 9i compatibility mode.