There are two different ways to load data in dimension tables. Conventional (Slow) – All the constraints and keys are validated against the data before, it is loaded; this way data integrity is maintained. Direct (Fast) – All the constraints and keys are disabled before the data is loaded. Once data is loaded, it is validated against all the constraints and keys. If data is found invalid or dirty it is not included in the index and all future processes are skipped on this data. (ALL Interview Questions)