Slowly changing dimensions
Type 1 overwrites the existing value with new value and does not retain history
Name ID Description laptop 0 xxxx phone 1 yyy ⇓Name ID Description laptop 0 zzz phone 1 yyy Type 2 add a new role for the new value and maintains the existing row for historical and reporting purposes
Name ID Description laptop 0 xxxx phone 1 yyy ⇓Name ID Description laptop 0 xxx phone 1 yyy laptop 0 zzz Type 3 allows storage of bith current value and previous vious of the dimension’s attributes in the same row, also it has the limited historical tracking. Last description go to prev Description column, updated description goes to current description column, change date reflects the modify time.
Name ID Prev Description Current Description Change date laptop 0 xxxx zzz 2024-04-29 phone 1 yyy mmm 2024-05-01