A Query Sampling Method for Estimating Local Cost Parameters in a Multidatabase System

نویسندگان

  • Qiang Zhu
  • Per- Ake Larson
چکیده

In a multidatabase system MDBS some query op timization information related to local database sys tems may not be available at the global level because of local autonomy To perform global query optimiza tion a method is required to derive the necessary local information This paper presents a new method that employs a query sampling technique to estimate the cost parameters of an autonomous local database sys tem We introduce a classi cation for grouping local queries and suggest a cost estimation formula for the queries in each class We present a procedure to draw a sample of queries from each class and use the ob served costs of sample queries to determine the cost parameters by multiple regression Experimental re sults indicate that the method is quite promising for estimating the cost of local queries in an MDBS

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تاریخ انتشار 1994