B. Ashadevi et. al. / (IJCSE) International Journal on Computer Science and Engineering Vol. 02, No. 09, 2010, 2820-2826 A Framework for the View Selection Problem in Data Warehousing Environment B. Ashadevi 1 Assistant Professor, Department of MCA. Velalar College of Engineering And Technology Thindal, Erode - 638012 Dr. R.Balasubramanian 2 Dean Academic Affairs, PPG Institute of Technology, Saravanampatty, Coimbatore-35 Dr. P.Navaneetham 3 Professor & Head of the Department, Department of MCA. Velalar College of Engineering And Technology Thindal, Erode - 638012 Abstract : A set of essential new concepts and tools have evolved into a new technology that makes it possible to access and produce accurate and timely management information for the competitive world. The phrase that has come to characterize this new technology is Data Warehousing (DW). The general problem of selecting an appropriate set of views to materialize is called the materialized view selection problem. In order to acquire a precise and quick response to an analytical query, proper selection of the views to materialize in the data warehouse is crucial. In traditional view selection algorithms, all relations are considered for selection as materialized views. Due to the space constraint and maintenance cost constraint, the materialization of all views is not possible. The primary goal of data warehousing is to select a suitable set of views that minimizes the total cost associated with the materialized views. In this paper, we present a framework, an optimized version of our previous work, for the view selection problem, which intends to achieve the best combination of low query processing cost, low view maintenance cost and good query response. All the cost metrics associated with the materialized views selection that comprise the query execution frequencies, base-relation update frequencies, query access costs, view maintenance costs and the system’s storage space constraints are considered by this framework. This framework optimizes the maintenance, storage and query processing cost and selects the most cost effective views to materialize. Thus, an efficient data warehousing system is the outcome. Keywords: Data Warehousing, Views, Materialization, View Selection, View-Maintenance, Query processing cost, Storage space. I. INTRODUCTION data warehouse is an information base that stores a large volume of extracted and summarized data for On-Line Analytical Processing and Decision Support Systems. To reduce the cost of executing queries in a data warehousing environment, frequently used aggregates queries are often pre-computed and materialized into summary views so that future queries can utilize them directly. Undoubtedly, materializing these summary views can minimize query response time. However, if the once data changes frequently, keeping these materialized views updated will inevitably incur a high maintenance cost. Furthermore, for a system with limited storage space and/or with thousands of summary views, we may be able to materialize only a small fraction of the views. Therefore, a number of parameters, including the query execution frequencies, base-relation update frequencies, query access costs, view maintenance costs and the system’s storage space constraints, should be considered in order to select an optimal set of summary views to be materialized. According to Inmon, W.H [1], a data warehouse is a subject-oriented, integrated, time-varying, nonvolatile collection of data that is used primarily in organizational decision making. The Data Warehouse is the heart of the architected environment, and is the foundation of all decision support system (DSS) processing. On-Line Analytical Processing (OLAP) and Decision Support Systems utilize the large volume of extracted and summarized data stored in an information base referred as a data warehouse [2]. The data warehousing technologies is the basis for the effective embarking of many industries, for instance, manufacturing financial services, transportation, telecommunications, utilities and healthcare. In order to collect data from many data sources, a data warehouse uses an update-driven approach that communicates through networks both locally and internationally. A solid platform of consolidated historical data is provided for analysis by the data warehouse system and it also distributes such analysis to local and remote users [3]. In order to provide effective solution for the queries posted to the data warehouse, the intermediate results obtained in the query processing are stored in the data warehouse. This can avert the access of the original data sources by the users [4]. A view is a derived relation defined in terms of base (stored) relations. A data warehouse holds multiple views and we have referred the materialized views as the views stored in the data warehouse. Materialized views are physical structures that precompute the intermediary results, thereby improving data access time. However, additional storage space and maintenance overhead A ISSN : 0975-3397 2820