How do you implement slowly changing dimensions in Datastage?
SCD-2 Implementation in Datastage: Slowly changing dimension Type 2 is a model where the whole history is stored in the database. An additional dimension record is created and the segmenting between the old record values and the new (current) value is easy to extract and the history is clear.
How do you implement SCD2 in DataStage?
How to Implement SCD using DataStage 8.1 –SCD stage?
- Source file that comes from the OLTP sources.
- Old dimesion refernce table link.
- The SCD stage.
- Target Fact Table.
- Dimesion Update/Insert link. Figure 1.
What are dimension tables in a star schema?
Dimension tables describe business entities—the things you model. Entities can include products, people, places, and concepts including time itself. The most consistent table you’ll find in a star schema is a date dimension table. A dimension table contains a key column (or columns) that acts as a unique identifier, and descriptive columns.
What do you need to know about star schema?
Star schema is a mature modeling approach widely adopted by relational data warehouses. It requires modelers to classify their model tables as either dimension or fact. Dimension tables describe business entities—the things you model.
Can you change the dimension of a fact table?
You would not add a record according to SCD2 rules in the fact table, if one of the dimension tables changes, in this design. This way you can model changes in each entity, like name changes in people, color changes in cars and the relationship between cars and people, for example ownership.
What does the slowly changing dimension stage do?
Slowly Changing Dimension stage The Slowly Changing Dimension (SCD) stage is a processing stage that works within the context of a star schema database. The SCD stage has a single input link, a single output link, a dimension reference link, and a dimension update link.