Getting started with Change Data Capture (CDC)

Products

• Datacom
• Datacom/DB
• Datacom/DB

Issue/Introduction

We are considering using Datacom Change Data Capture (CDC) and have some general questions:

1. Can all application tables be monitored by CDC?
2. What is the added overhead?
3. What is CDC Plus and what does it buy?
4. Can the monitor be on the mainframe and the listener be on another platform? 

Environment

z/OS

Datacom/DB

Resolution

Here are the answers:

1) Can all application tables be monitored by CDC? 
==> Yes, as long as the application tables are defined with LOG=YES, RECOVERY=YES 

2) What is the added overhead? 
==> Overhead is variable and is based on how much maintenance activity is being captured. For most shops maintenance activity is a small percentage of the requests (10-15%).

Overhead can be shifted from the production MUF for CDC activity to a special CDC replication MUF. The CDC replication MUF does not reduce the overhead, but moves it out of the production MUF to a separate address space 

3) What is CDC Plus and what does it buy? 
==> CDC plus allows the user to separate the captured changes to different (max 9) CDC repository databases. The separate databases allow the customer to separate captured changes by monitored table name so they can be isolated into separate repository databases according to application function or security requirements. 

4) Can the mainframe send CDC to another platform? 
==> CDC itself does not "send" data to other platforms -- it just captures the changes and stores them is a standard database table to be processed. Datacom has a listener/applier process specific to Datacom MUF (zOS) to Datacom MUF (zOS) movement (replication) thru MQ. This is part of an Active/Query implementation.  There are 3rd parties (like Power Exchange, GT Software) that have tools that read the Datacom CDC database and forward the changes to off platform processes. 

Additional Information

See Change Data Capture (CDC) documentation and CDC Plus databases:
http://docops.ca.com/ca-datacom/15-1/en/administrating/ca-datacom-db-database-and-system-administration/using-the-multi-user-facility/change-data-capture

http://docops.ca.com/ca-datacom/15-1/en/administrating/how-to-build-the-cdc-plus-databases