SCD Type 2,Slowly Changing Dimension Use,Example,Advantage,Disadvantage

In Type 2 Slowly Changing Dimension, a new record is added to the table to represent the new information. Therefore, both the original and the new record will be present. The new record gets its own primary key.

In our example, recall we originally have the following table:

Customer Key	Name	State
1001	Williams	New York

After Williams moved from New York to Los Angeles, we add the new information as a new row into the table:

Customer Key	Name	State
1001	Williams	New York
1005	Williams	Los Angeles

Advantages

• This allows us to accurately keep all historical information.

Disadvantages

• This will cause the size of the table to grow fast. In cases where the number of rows for the table is very high to start with, storage and performance can become a concern.
• This necessarily complicates the ETL process.

Usage

About 50% of the time.

When to use Type 2

Type 2 slowly changing dimension should be used when it is necessary for the data warehouse to track historical changes.