Using Changed Data Capture (CDC) - simple

As mentioned during the introduction of this chapter, one of the more commonly used ETL/ELT methodologies is CDC. This generic term refers to the means by which a data migration design can identify source data, which has been altered in some way (that is, inserted, updated, or deleted). By focusing only on changed data, a migration strategy can avoid having to move an entire set of data, a process that is usually done only during an initial data load.

When determining which ODI KMs and CDC methods to use, a developer/architect should consider several of the following points:

• The availability of pre-existing timestamp attributes on source systems tables

• The database privileges required to create table triggers on the source system

• The availability of database log files and corresponding internal CDC delivery mechanisms (that is, Oracle Logminer, Oracle Streams, and so on)

• The availability of Oracle Golden Gate for specific technologies

Oracle Data Integrator...