EXCLUSIVE CONTROL METHOD, EXCLUSIVE CONTROLLER, RECORDING MEDIUM IN WHICH EXCLUSIVE CONTROL PROGRAM IS RECORDED AND DATA BASE SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an exclusive controller of a data base system in which inquiry optimization to optimize transaction performance efficiency of a system is performed. SOLUTION: The exclusive controller in the data base system is provided with a means (2) to generate lock processing procedures including a locking operation and an unlocking operation for simultaneous performance control of transaction, a means (3) to prepare access plans for the inquiry optimization in which a generated lock processing procedure is fetched as a data operation, a means (4) to evaluate costs of the access plans including efficiency of simultaneous practicability of the transaction for the prepared access plans and a means (5) to select an optimal access plant based on the evaluated costs among the prepared access plans.