Change Data Capture – Oracle CDC

CDC : is database functionality that helps in capturing incremental changes to Oracle Database.

Terminology in CDC
Publisher
: is database user that publishes captured changed data
Subscriber: is database user that consumes changed data
Change Tables: Changes in database are written to change tables
Subscriber Views: are database views against change tables for subscribers.

Note* -> One publisher can support multiple subscribers

CDC Implementation Methods

A) Synchronous CDC – In this method changes are captured synchronously from source database into change tables. This method uses internal database triggers.

B) Asynchronous Autolog CDC– This method requires staging database separate from source database. Redo logs are transferred from source database to staging database using redo transport service (You can also manually transfer redo and register them to staging database) and changes are captured at staging database. There are two modes available
i) Autolog online CDC  ii) Autolog archived CDC

– Source and Target database should be on same operating system and on same database version.
– SYS password on source and target database must be same.
– Source & Staging database should run in archive mode

C) Asynchronous Hotlog CDC – In this method, online redo log file is used to capture changes and changes are captured at source database itself. Separate process mines redo logs and captures changes in change tables.

D) Asynchronous Distributed Hotlog CDC– This method require staging database. Changes capture is performed by separate process on source database and then propagated to staging database and written to change tables (in staging database). For this method underlying infrastructure is provided by Oracle Streams.

– Source & Staging database should run in archive mode

Related Documentation

More on CDC and implementation with E-Business Suite (Oracle Applications) coming soon…

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About the Author Atul Kumar

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7 comments
chanchal123 says June 23, 2008

How to setup the publisher and subscriber on two different machines.

Reply
Srikanth Mahalingam says August 19, 2009

Can the CDC be implemented on eBusiess Suite implementation – any references?
Particularly Release 12…?

Thanks,
Srikanth

Reply
Srikanth Mahalingam says August 19, 2009

We want to implement change data capture feature on the database, so would like to know if it is done on any eBusiness implementations..?

Reply
Atul Kumar says August 19, 2009

Yes you can implement CDC in EBS database : Check 370629.1 Change Data Capture (Cdc) and Oracle Applications 11i, this note is for 11i but same can be applied to R12

For more information on CDC check

http://download.oracle.com/docs/cd/B19306_01/server.102/b14223/cdc.htm

http://www.oracle.com/technology/products/bi/db/10g/pdf/twp_cdc_cookbook_0206.pdf (CDC cookbook)

Reply
paps12 says October 21, 2009

Hi

Have you implemented CDC on any of the applications.

Regards,
PKB

Reply
sgovindaiah says February 4, 2010

Hi,

I have set-up CDC using Asynchronous capture method. I wanted to understand if we remove DBA access provided to Publisher on source database and publisher on Staging data what would happen. Is there any way of implementing CDC without giving DBA access.

Reply
appaub says October 16, 2011

I am not a technical prson and have a simple question relating to CDC.
Can CDC work in Oracle R12 as itworks in 11i? H
Is there any change at all in relation to R12?

Thanks
Akwasi Appau

Reply
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