1. Have unknown member in Dimension table
It is often useful to have a pre-established "no such member" or "unknown member" record in each dimension to which orphan fact records can be tied during the update process. Business needs and the reliability of consistent source data will drive the decision as to whether such placeholder dimension records are required
2. Avoid using GUIDs as keys
You should avoid using GUID as key in the data warehouse database. GUIDs may be used in data from distributed source systems, but they are difficult to use as table keys. GUIDs use a significant amount of storage (16 bytes each), cannot be efficiently sorted, and are difficult for humans to read. Indexes on GUID columns may be relatively slower than indexes on integer keys because GUIDs are four times larger.
