Question - What are the different types of SCD?
Answer -
There are six sorts of Slowly Changing Dimension that are commonly used. They are as follows:
Type 0 – Dimension never changes here, dimension is fixed, and no changes are permissible.
Type 1 – No History Update record directly. There’s no record of historical values, only the current state. A kind 1 SCD always reflects the newest values, and when changes in source data are detected, the dimension table is overwritten.
Type 2 – Row Versioning Track changes as version records which will be identified by current flag & active dates and other metadata. If the source system doesn’t store versions, then it’s usually the info warehouse load process that detects changes and appropriately manages the change during a dimension table.
Type 3 – Previous Value column Track change to a selected attribute, add a column to point out the previous value, which is updated as further changes occur.
Type 4 – History Table shows the current value in the dimension table. All changes are tracked and stored in a separate table.
Hybrid SCD – Hybrid SDC utilizes techniques from SCD Types 1, 2, and three to trace change.
Only types 0, 1, and a couple of are widely used, while the others are applied for very specific requirements.