About the Change Data Capture Transformations
Change Data Capture Defined
Change data capture (CDC) is a process that shortens the time required
to load data from a relational database. The process is efficient
because the source is a changed data table, rather than the entire
base table.
The CDC transformations
in SAS Data Integration Studio are used to load dimension tables in
star schemas, as part of an implementation of slowly changing dimensions.
For more information, see About Slowly Changing Dimensions.
The following diagram
illustrates a job that loads changed data into a dimension table.
The temporary target table that is generated by the CDC transformation
is the source for the SCD Type 2 Loader transformation.
SAS Data Integration
Studio provides four CDC transformations: Oracle CDC, DB2 CDC, Attunity
CDC, and General CDC. The Oracle, DB2, and Attunity transformations
work directly with changed data tables that are in native database
format. The General CDC transformation loads change data from other
vendors or from your own custom applications.
The CDC transformations
are available in the Transformations tree under the heading Change
Data Capture.
The CDC transformations
require you to install and configure change data capture software
on your relational database, and then use that software to generate
changed data tables. For details, see the topic that describes the
prerequisites for each of the CDC transformations.
All of the CDC transformations
require you to supply a source changed data table. Additionally, the
CDC transformations can be configured to read a control table. The
primary purpose of the control table is to allow only one write to
each record in the target. For information about control tables, see About CDC Control Tables.
Prerequisites for Change Data Capture
The CDC transformations
require the following software:
Attunity CDC
Attunity is a data
integration product, in which the Attunity Stream software enables
connectivity between databases and across operating environments.
The Attunity CDC transformation has been validated on Attunity AIS
5.0 with Attunity Stream. To use the Attunity software you need to
license SAS/ACCESS Interface to ODBC.
Oracle CDC
The Oracle CDC transformation
has been validated on Oracle 10G with asynchronous CDC. The transformation
requires that you license SAS/ACCESS to Oracle. Note that Oracle CDC
supports Asynchronous Autolog Publishing.