Abstract
The Traditional data warehouse did not contain data as today. Hence, it is difficult to retrieve these data and treat them. Furthermore, its content is not updated, which may lead to bad decisions. Data are typically loaded from conventional operational systems. Given that today's decisions, in the business world, are becoming more and more in real time. Thus, the system supporting these decisions is to be held. In this paper, we are interested in giving a survey on data warehousing starting from a traditional data warehouse to a real time data warehouse. This survey, focus firstly, on data warehouse architecture. Secondly, it details the changes in the Extract-Transform-Load process to deal with real time data warehousing. Thirdly, it sketches the integration data in the real time data warehouse. Finally, a comparative study concerning the real data warehouse approaching is also presented in this paper.