Block Access Estimation for Data Using a Finite LRU
Fabio Chiodo Grandi · 1993
Data access cost evaluation is fundamental in the design and management of database systems. When some data items have duplicates, a clustering effect which can heavily influence access costs is observed. The availability of a finite amount of buffer memory in real systems has an even more dramatic impact, In this paper a comprehensive cost model for clusterwl data retrieval by an index using a finite buffer is presented. Our appmch combines and extends previous models based either on finite buffer or on uniform data clustering assumptions. The computational cost of the formulas we propose in this work is independent of the data size or of the query cardinality and need only a single statistics per sealrh key, the clustering factor, to be maintained by the system. The predictive power and the accuracy of the model are shown in comparison with actual costs resulting from simulations.