CDC Guide for z/OS

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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.

For nonrelational sources, you must import extraction maps.

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, you cannot run a CDC session that contains a mapping with both VSAM and IMS source definitions, even if changes for those sources are in the same change stream. Instead, create unique a mapping and session for the VSAM sources and a separate, unique mapping and session for the IMS sources. PowerExchange reads the change stream twice: once for the session with the VSAM sources, and once for the session with the IMS sources.

The following figure shows an example mapping in PowerCenter Designer with three DB2 sources:

If you include this mapping in a session that uses a PWX DB2zOS 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, such as PowerExchange Logger for z/OS 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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CDC Guide for z/OS

CDC Guide for z/OS

Multiple-Source Processing in CDC Sessions

Multiple-Source Processing in CDC Sessions