Data WareHouse :: Technology, Database

existence a market leader today requires competitive advantage all over rival organizations. By investing in information w arehouses, organizations can repair predict the trends in market and offer services best suitable to the needs of their customers. A Data Warehouse (DW) can be delimit as a subject-oriented, non-volatile informationbase having records over years 1,2. DWs support the strategic decision-making operation and help to answer questions such as Who was our best customer for this relic last year?3.Different DW systems consists of different components, however, some core components are shared by most DW systems. The first component is the data sources. DW receives foreplay from different data sources (such as Point-Of-Sales (POS) systems, Automated Teller Machines (ATM) in banks, stoppage terminals etc). The second component is the data staging area. The data comes from data sources and it is fit(p) in the staging area, where the data is treated with differen t transformations and cleansed of any anomalies. aft(prenominal) this transformation, the data is placed in the third component which is kn declare as storage area, which is usually a Relational Database Management System (RDBMS). This procedure of data extraction from data sources, transformation and finally loading in storage area is regarded as Extract, Transform and Load (ETL). The saved data from the storage can be viewed by reporting units. Different on-line(a) Analytical Processing (OLAP) tools assist in generating reports based on the data saved in the storage area 4,5,6,7,8.We believe that testing should be ingrained in DW development. Thus, each of the DW components should be tested. One of the main challenges in testing the DW systems is the fact that DW systems are different among organizations, each organization has its own DW system that conforms with its own requirements and needs, which leads to having differences between DW systems in several aspects (such as dat abase technology, tools used, size, weigh of users, number of data sources, how the components are connected, etc.)9. Another big challenge that is set about by the DW testers is regarding the test data preparation. Making use of real data for testing purpose is a violation of citizens privacy laws in some countries (for example, using real data of bank accounts and other information is illegal in many countries). For a proper testing of a DW, front of a huge amount of test data is necessary. In real-time environment, the system may behave differently in the presence of terabytes of data 10.