CDC Guide for z/OS

10.5.2
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- 10.5.6
- 10.5.5
- 10.5.4
- 10.5.3
- 10.5.1
- 10.5
- 10.4.1
- 10.4.0 HotFix 1
- 10.4.0

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IMS CDC Overview

PowerExchange change data capture (CDC) for IMS captures changes made to IMS databases and logs those changes to PowerExchange Logger for z/OS log files.

You can use PowerCenter CDC sessions to extract the captured change data from the PowerExchange Logger log files or from PowerExchange Condense condense files and apply that data to one or more target databases.

PowerExchange provides the following alternative methods for performing IMS CDC:

Synchronous IMS CDC
. Captures changes as they occur and logs them to the PowerExchange Logger. The IMS synchronous ECCR runs as separate subtasks in IMS regions such as the control region, DBCTL, DL/1, and DBB batch jobs.

Log-based IMS CDC
. Asynchronously captures changes by reading them from the IMS archive logs and logging them to the PowerExchange Logger. The IMS log-based ECCR runs in a separate address space as a started task or a batch job.

The following table compares IMS synchronous CDC and the IMS

log-based

CDC methods:

Feature	IMS Synchronous CDC	IMS Log-Based CDC
Does real-time capture of change data.	Yes	No
Reads IMS archive logs to capture IMS change data asynchronously.	No	Yes
PowerExchange IMS interface modules install into the IMS RESLIB.	Yes	No
Uses the IMS external subsystem to communicate with IMS ECCR.	Yes	No
PowerExchange libraries must be added to the IMS region JCL.	Yes	No
An EXIT statement must be added to the DBD for each database from which you capture changes.	No	Yes
All databases from which you capture changes must be registered in DBRC.	No	Yes
ECCR uses the current RECON data set to determine which IMS archive logs to process.	No	Yes
Captures change data within an IMSplex.	Yes	No
Captures multiple segments with a single capture registration.	No	Yes
Captures non-keyed and non-uniquely keyed segments.	Yes	No
Captures changes from segments that have had compression exits applied.	Yes	Yes
Adds additional data to the IMS log data sets.	No	Yes