Name the types of SCD.
There are six types of Slowly Changing Dimension that are:
Type 0: Dimension never changes here, dimension is fixed, and no changes are permissible.
Type 1: 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 is 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.
Hybrid SCD: Hybrid SDC uses techniques from SCD Types 1, 2, and three to trace change.