There are many different of ways are there which is two different ways to load data in dimension tables.
> Direct (Fast) : It is the basically use for the loading purpose in this way All the constraints and keys are can be disabled before the data is loaded. Once a tym data is loaded, it is validated against all the constraints and keys. If data is found invalid or dirty it is not included in index and all future processes are skipped on this data.
> Conventional (Slow) : It is basically for the All the constraints and keys are validated against the data before, it is loaded, this way data integrity is maintained.