Patent ID: 7805410

Claim:
A load estimating system which estimates a load of a database, comprising: a storage unit configured to include structure information defining a structure of a table in said database, first distribution information indicating probability distribution of condition variables of a query for said table, and second distribution information indicating probability distribution of values in said table; a record number calculating module configured to calculate the average number of selected records which meet conditions defined by condition variables, based on said structure information, said first distribution information and said second distribution information; and an access number calculating module configured to calculate the number of block accesses for said query based on the average number of selected records wherein said condition variables define value ranges, wherein said first distribution information indicates probability distribution of said value ranges, wherein said record number calculating module calculates an average selection range which is an average value of said value ranges, based on said first distribution information, wherein said record number calculating module calculates a record range which is an average value of value ranges taken by said values per record, based on the total number of a plurality of records and said second distribution information, and wherein said record number calculating module calculates the average number of selected records by dividing said average selection range by said record range.