26
DBMS_LOGMNR_CDC_PUBLISH

Oracle Change Data Capture identifies new data that has been added to, modified, or removed from relational tables and publishes the changed data in a form that is usable by an application.

This chapter describes how to use the DBMS_LOGMNR_CDC_PUBLISH supplied package to set up an Oracle Change Data Capture system to capture and publish data from one or more Oracle relational source tables. Change Data Capture captures and publishes only committed data.

Typically, a Change Data Capture system has one publisher that captures and publishes changes for any number of Oracle source (relational) tables. The publisher then provides subscribers, typically applications, with access to the published data.

This chapter discusses the following topics:

• Publishing Change Data
• Summary of DBMS_LOGMNR_CDC_PUBLISH Subprograms

Publishing Change Data

The publisher, typically a database administrator, is concerned primarily with the source of the data and with creating the schema objects that describe the structure of the capture system: change sources, change sets, and change tables.

Most Change Data Capture systems have one publisher and many subscribers. The publisher accomplishes the following main objectives:

1. Determine which source table changes need to be published.
2. Use the procedures in the DBMS_LOGMNR_CDC_PUBLISH package to capture change data and makes it available from the source tables by creating and administering the change source, change set, and change table objects.
3. Allow controlled access to subscribers by using the SQL GRANT and REVOKE statements to grant and revoke the SELECT privilege on change tables for users and roles.

   This is necessary to allow the subscribers, usually applications, to use the DBMS_LOGMNR_CDC_SUBSCRIBE procedure to subscribe to the change data.