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English
  • PowerExchange for CDC and Mainframe 10.5
  • All Products

Table of Contents

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  1. Preface
  2. Part 1: PowerExchange CDC Introduction
  3. Part 2: PowerExchange CDC Components
  4. Part 3: PowerExchange CDC Data Sources
  5. Part 4: Change Data Extraction
  6. Part 5: Monitoring and Tuning
  7. Appendix A: DTL__CAPXTIMESTAMP Time Stamps

CDC Guide for Linux, UNIX, and Windows

CDC Guide for Linux, UNIX, and Windows

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Multiple-Source Processing in CDC Sessions

Multiple-Source Processing in CDC Sessions

When you use PWX CDC application connections to extract change data, PowerExchange reads the change stream in a single pass for all source definitions in the mapping. The sources must be of the same type and use the same change stream.
To create source definitions in Designer, import source metadata in one of the following ways:
  • Import a PowerExchange extraction map by using the
    Import from PowerExchange
     dialog box.
  • Import table definitions from a relational database by using the
    Import from PowerExchange
    dialog box or the
    Import from Database
     dialog box.
Informatica recommends that you import extraction maps. It makes creating mappings and sessions easier for the following reasons:
  • The source definition contains the extraction map name. You do not need to provide this name when you configure the session.
  • The source definition contains the PowerExchange-generated CDC columns, such as the DTL__CAPX columns. You do not need to add these columns to the source definition.
During change data extraction, PowerExchange processes all source definitions in the mapping that have the same source type. Do not include multiple data source types in the mapping. Otherwise, the CDC session fails with message PWXPC_10080.
For example, do not run a CDC session that contains a mapping with both Db2 and Oracle source definitions, even if changes for those sources are in the same change stream. Instead, create a mapping and session for all of the Db2 sources and a separate, unique mapping and session for all of the Oracle sources. PowerExchange reads the change stream twice: once for the session with the Db2 sources, and once for the session with the Oracle sources.
The following figure shows an example mapping in PowerCenter Designer that includes three Db2 sources: 
If you include this mapping in a session that uses a PWX DB2LUW CDC application connection, PowerExchange reads the change stream and extracts changes for all three source tables in a single pass. PowerExchange extracts change data in chronological order, based on when the UOWs completed. PowerExchange passes the change data to PWXPC, and PWXPC provides the changes to the appropriate source qualifier.
If you create a workflow that contains multiple CDC sessions, PowerExchange uses a connection for each session, even if the sessions extract change data from the same change stream. For example, the sessions might extract change data from the same PowerExchange Logger log files.
Because the example mapping uses source definitions created from extraction maps, it cannot be used for bulk data movement operations. However, mappings that use source definitions created from database relational metadata can be used for either change data extraction or bulk data movement. 
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