PowerExchange Express CDC for Oracle is more efficient and faster than PowerExchange Oracle CDC with LogMiner in many Oracle environments. PowerExchange Express CDC does not use Oracle LogMiner to read the redo logs. It has its own log reader to get change data directly from the redo logs for real-time extraction processing. This architecture avoids the performance degradation that can occur on Oracle systems because of initialization of LogMiner sessions.
Also, PowerExchange Express CDC for Oracle does not use the PowerExchange UOW Cleanser. PowerExchange Express CDC capture components handle UOW Cleanser functions transparently for CDC sessions that run in real-time extraction mode. The capture components produce a change stream in which inserts, updates, and deletes are organized by transaction, and the transactions are arranged in their original commit order.
If you currently use Oracle CDC with LogMiner and need better CDC performance, consider migrating to PowerExchange Express CDC for Oracle.
You cannot use both PowerExchange Express CDC for Oracle and PowerExchange Oracle CDC with LogMiner in the same PowerExchange instance with the same dbmover.cfg and pwxccl.cfg configuration files.
PowerExchange Express CDC can capture change data from most types of data source environments, including Oracle RACs that use Automatic Storage Management (ASM), Oracle Data Guard logical or physical standby databases, Oracle Exadata database machines, and Oracle multitenant pluggable databases. Also, PowerExchange Express CDC can capture change data in an Amazon Elastic Compute Cloud (EC2) environment.
With PowerExchange Express CDC, use of the PowerExchange Logger for Linux, UNIX, and Windows is optional but strongly recommended. The PowerExchange Logger writes successful units of work (UOWs) in chronological order by end time to PowerExchange Logger log files. CDC sessions can then extract the change data from the PowerExchange Logger log files in either continuous extraction mode or batch extraction mode. Benefits of using the PowerExchange Logger include fewer database accesses, faster CDC restart, and no need for prolonged retention of the Oracle redo files for CDC.
To configure PowerExchange Express CDC, you must add some Oracle-specific statements to the DBMOVER configuration file and define the separate PowerExchange Express CDC configuration file, which has the default file name of pwxorad.cfg. Also, create capture registrations, configure PowerCenter CDC sessions, and configure restart processing, as normal. The restart token format for PowerExchange Express CDC for Oracle sources is different from that for any other data source type, including Oracle CDC with LogMiner sources.
You must also perform some configuration tasks in Oracle. PowerExchange Express CDC requires the Oracle database to run in ARCHIVELOG mode with minimal global supplemental logging enabled.
