The PowerExchange Client for PowerCenter can extract change data for relational and nonrelational sources directly from the change stream in real time.
The change stream contains the source data changes in time-sequence order. As a result, the changes in a single unit of work (UOW) are not contiguous in the change stream. The UOW Cleanser reconstructs the UOWs into complete and consecutive UOWs based on transaction end time. The UOW Cleanser functionality is incorporated into PowerExchange CDC solutions for Db2 LUW, Microsoft SQL Server, MySQL, Oracle Express, and PostgreSQL sources but is a separate task for all other PowerExchange CDC sources.
When you use PWX CDC Real Time application connections to extract change data, PWXPC connects to PowerExchange through the PowerExchange Call Level Interface (SCLI) and specifies the PowerExchange CAPXRT access method. PowerExchange reads change data from the change stream for all sources in the mapping in a single pass. PWXPC real-time sessions run for a specified period or continuously until stopped.
The following image shows the change data flow from PowerExchange to the PowerCenter target tables: