Slowly Changing Dimension

Data warehouse data are never over-written or deleted - once committed, the data are static, read-only, and retained for future reporting use. Enterprise operation is not constant, it will variant and measurement data may vary when update the business operation.

Sales_Price up and down based on the marketing demand, Employee may transfer from one office location into another office location and Contact_Address may change when Customer or Supplier relocate from one place into another place.

Periodical Sales Analytical Report may vary when change the Sales_Price or Sales_Tax like that Geographical Sales Analytical Report may vary when change the Contact_Address data within the report period of time.

Slowly Changing Dimension is used to maintain slowly changing data rather than changing data on a time-based, regular schedule. Slowly Changing Dimension categories into SCD Type 01, SCD Type 02, SCD Type 03 and Hybrid SCD that based on data storage technique.

SCD Type 01

SCD Type 01 method is used to overwrite old data with new data in the Data warehouse. An instance, OLTP data may have mistake or wrong spelling or numeric mistake. After transfer mistake data from OLTP into Data warehouse, SCD Type 01 method is used to correct mistake data in the Data warehouse. SCD Type 01 method doesn't maintain historical data that is not good idea to maintain Slowly Changing Data in the Data warehouse.
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