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 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.
The Oracle CDC transformation
has been validated on Oracle 10G with asynchronous CDC. The transformation
requires that you license SAS/ACCESS to Oracle.