Research in the data warehousing area focuses on design issues, 
data maintenance and query optimization. Recently new research 
areas appeared that are related to dynamicity of data sources. 
Dynamicity of data sources can be categorized into: data updates, 
schema and instance changes, and constraint modifications. Existing 
data warehouse systems manage data updates. However, they are unable 
to follow schema and instance changes and constraint modifications.
In this paper we analyze schema and instance changes caused by dynamically 
changing external data sources. We advocate the need to apply the external 
data source schema changes to a data warehouse and we present modeling 
issues involving star schema evolution and data warehouse versioning. 
Finally, we show query processing in presence of different data warehouse versions.

Key words: temporal data warehouses, advanced OLAP queries, schema change in data warehouse