Patent ID: 7734616

Claim:
A storage system, comprising: connection means for connecting with a computer in which a database management system is operating; a storage device including a plurality of locations; information acquisition means for acquiring from said database management system through said connection means information on a data structure including a table, an index, and a log defined by a schema in a database management system of said database management system, information on recording locations in said storage device in which database data managed by said database management system is classified according to a data structure defined by said schema, and information on databases managed by said database management system including a query execution plan of a query with process priority information executed by said database management system, wherein said query execution plan includes information on a process order that is used to determine an execution order of processes executed by said database management system, the query execution plan further including information identifying a number of process groups each representing a set of processes to be executed at a time, the processes belonging to a first process group not being executed until after execution of all processes in a second process group, the second process group having a higher priority than the first process group; a cache memory storing therein said process priority information on said database; cache memory control means for managing said cache memory for prefetching; wherein said cache memory control means executes a prefetch preferentially to data of said database having a higher priority by referring to said process priority information or to said database data used by a process given a higher priority; wherein said cache memory control means makes a control of allocating a higher amount of cache memory to data of said database having a higher priority by referring to said process priority information or to said database data used by a process given a higher priority; and a storage controller for controlling to predict an index access destination in said plurality of locations of said storage device to be made for prefetching based on comparison of said process priority information and interpretation of said information acquired by said information acquisition means when interpretable.