In this paper, we first introduce the readers to four current query processing techniques that are used in Data Warehousing queries. This is followed by a description of a cost model that we have adopted and later to be used when we compare the performance of the different query processing techniques. The performance of these query processing techniques are compared using a disk I/O. Finally, we propose a recommendation for Database Management Systems (DBMSs) to select the most cost-effective query processing techniques based on the cost model.