Load estimating system and computer load estimating method
First Claim
1. 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, andwherein said record number calculating module calculates the average number of selected records by dividing said average selection range by said record range.
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Abstract
A load estimating system which estimates a load of a database, includes a storage unit, a record number calculating module, and an access number calculating module. The storage unit includes 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. The record number calculating module calculates 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. The access number calculating module calculates the number of block accesses for said query based on the average number of selected records.
8 Citations
16 Claims
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1. A load estimating system which estimates a load of a database, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of estimating a computer load, which estimates a load of a database, comprising:
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reading structure information defining a structure of a table in said database from a storage unit; reading first distribution information indicating probability distribution of condition variables of a query for said table from said storage unit; reading second distribution information indicating probability distribution of values in said table from said storage unit; calculating 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 calculating the number of block accesses for said query based on the average number of selected records wherein said structure information indicates the total number of a plurality of records in said table and a size of each of said plurality of said records, wherein said condition variables define value ranges, wherein said first distribution information indicates probability distribution of said vale ranges, wherein said step of calculating the average number of selected records, includes; calculating an average selection range which is an average value of said value ranges, based on said first distribution information, calculating a record range which is an average value of value ranges taken by said values per record, based on the total number of said plurality of records and said second distribution information, and calculating the average number of selected records by dividing said average selection range by said record range. - View Dependent Claims (14)
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15. A computer program product for a method of estimating a computer load, which estimates a load of a database, embodied on a computer-readable medium and comprising code that, when executed, causes a computer to perform the following:
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reading structure information defining a structure of a table in said database from a storage unit; reading first distribution information indicating probability distribution of condition variables of a query for said table from said storage unit; reading second distribution information indicating probability distribution of values in said table from said storage unit; calculating the average number of selected records which meet conditions defined by condition variables, based on said structure information, based on said structure information, said first distribution information and said second distribution information; and calculating the number of block accesses for said query based on the average number of selected records wherein said structure information indicates the total number of a plurality of records in said table and a size of each of said plurality of said records, wherein said condition variables define vale ranges, wherein said first distribution information indicates probability distribution of said value ranges, wherein said step of calculating the average number of selected records, includes; calculating an average selection range which is an average value of said value ranges, based on said first distribution information, calculating a record range which is an average value of value ranges taken by said values per record, based on the total number of said plurality of records and said second distribution information, and calculating the average number of selected records by dividing said average selection range by said record range. - View Dependent Claims (16)
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Specification