A Change Data Capture tracks or consumes changes in a data source using streams. A stream is a point in a data base’s change log that is used as a point of reference by the CDC agent. Each time you begin to start a Change Data Capture, a new stream, with a unique name is automatically created. You can have as many concurrent streams as necessary. The place where the changes are currently being consumed is called the stream position. The stream position is automatically saved in the data base.
You can filter a stream to consume for selected tables in the data base or for all of the tables.
The following are the parts of the CDC stream:
  • Data Source: The native data source where you are consuming changes. For example, Adabas.
  • Change Logger: This is the native tool that logs changes for a data source.
  • Change Source: This is the data source log. It contains various information depending on the data source and the log configuration. This part has a different name depending on the data source you are working with. For example, for Adabas this is called the PLOG, for DB2 it is called a journal, and for Oracle it is called REDO logs. For more information, see the Overview for a list of the CDC agents.
  • Change Capture Agent: This is the Attunity CDC Agent. The agent consumes the changes from the Change Source and outputs them into a standard XML format.