|Title:||A case study for the design and selection of materialized views in a data warehousing environment|
|Subject:||Data warehousing -- Case studies|
Hong Kong Polytechnic University -- Dissertations
Department of Computing
|Pages:||ix, 103 leaves : ill. ; 31 cm|
|Abstract:||The present study attempts to design a data warehouse system for an engineering company 'R'. This system aims to assist users in retrieving data for business analyses in an efficient manner. The structural design of this data warehousing system has applied the latest dimensional modeling concepts of star and snowflake schemes. Furthermore, frequently accessed dimension keys and attributes are stored in various summary views in order to minimize the query processing cost. A cost model was implemented to enable the evaluation of the total costs and benefits involved in selecting each materialized view. Using the cost analysis methodology for evaluation an adapted greedy algorithm has been implemented for the selection of materialized views. This algorithm takes into account all of the cost variables associated with the materialized views selection method (i.e. query access frequencies, base-data update frequencies, query access costs, view maintenance costs and the availability of the system's storage). The algorithm and cost model were applied to a set of real-life databases extracted from company 'R'. Hence, by selecting the most cost effective set of materialized summary views, the total maintenance, storage and query costs of the system can be calculated and optimized. Thereby, an efficient data warehousing system can be constructed. The total cost of five test conditions (composed of differing query patterns and frequencies) were evaluated using three different view materialization strategies: i. an all virtual views method. ii. an all materialized views method. iii. a selection of materialized views method. The total costs evaluated from using the selection of materialized views method were proved to be the smallest among these three different view materialization strategies in all cases. An experiment was installed to record the program execution time of these three view materialization strategies for computation of a fixed number of queries and maintenance processes. The shortest total processing time was recorded by using the selection of materialized views method. General guidelines for data warehouse design and materialized views selection are presented and a prototype of this data warehouse system was implemented using a commercially available data warehousing software "Oracle-Discoverer".|
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