METHOD OF DATABASE MANAGEMENT, DATABASE MANAGEMENT DEVICE AND DATABASE MANAGEMENT PROGRAM

摘要

A database system is provided with a storage device which stores a database, and a memory which stores a portion of the database stored in the storage device, and the data stored in the memory and in the storage device is accessed and processed; whereby when a table and an index are stored in memory, the processing cost when the index is used and when the index is not used are calculated on the basis of statistical information, and it is determined on the basis of the calculated processing cost and the memory usage for the index whether or not the index is to be located in memory.