Data prefetching method
First Claim
1. A data prefetching method in a computer system including a first computer which a database management system operates, a storage device which is connected to the first computer, stores data of a database which the database management system manages and has a cache memory, and a second computer which is connected to the first computer and uses the data of the database, comprising the steps of:
- sampling a processing content which satisfies given conditions from a content of processing which is executed by the database management system;
determining a data prefetching method based on the sampled content;
instructing prefetching of data based on the data fetching method to the storage device when the content of the processing is executed; and
instructing completion of the data fetching to the storage device when the execution of the content of the processing is completed.
1 Assignment
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Accused Products
Abstract
A prefetching program preliminarily executes acquisition of SQL statements which are executed repeatedly and an analysis of a content of such processing so as to grasp data to be fetched in advance. Immediately before executing the processing, starting of the processing is notified to the prefetching program. Based on a preliminary analysis result and a given cache amount, the prefetching program issues a setting of the cache amount and an instruction of a data prefetching method to a DBMS and a storage device. The prefetching program receives a report on completion of the processing and, thereafter, issues a request for releasing a cache allocated for the processing to the DBNS and other storage devices.
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Citations
20 Claims
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1. A data prefetching method in a computer system including a first computer which a database management system operates, a storage device which is connected to the first computer, stores data of a database which the database management system manages and has a cache memory, and a second computer which is connected to the first computer and uses the data of the database, comprising the steps of:
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sampling a processing content which satisfies given conditions from a content of processing which is executed by the database management system;
determining a data prefetching method based on the sampled content;
instructing prefetching of data based on the data fetching method to the storage device when the content of the processing is executed; and
instructing completion of the data fetching to the storage device when the execution of the content of the processing is completed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A data prefetching program which is executed by a computer system including a computer which operates a database management system and a storage device which stores data of a database which the database management system manages and has a cache, the data prefetching program comprising:
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acquiring information on a content of processing which is executed by the database management system;
acquiring information on mapping of data respectively from the database management system, the computer and the storage device;
acquiring information indicative of starting of processing;
determining a data prefetching method using the acquired information;
giving the data prefetching method to the storage device;
acquiring information indicative of completion of processing; and
instructing releasing of the data prefetching method to the storage device. - View Dependent Claims (14)
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15. A program for managing prefetching of data of as a cache which is executed in a computer system including a storage device which has a plurality of logical disk devices which stores data and a cache which stores a copy of the data stored in the logical disk devices and a database management system DBMS which executes management of reading and writing of the data from the storage device, the program comprising:
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an information acquisition module for acquiring information on a prefetching job including information on a program of an object which issues a prefetching instruction and information on a DBMS constitution from the DBMS, an SQL analysis module for grasping a repetition group based on information on SQL statements (statements described in a structural inquiry language in the same form) which a job program designated by the acquired prefetching job information issues and, at the same time, for setting a structure of access data and an access method based on an execution plan of the SQL statements acquired from the DBMS;
a prefetching method determination module for determining a cache amount of the DBMS and a cache prefetching method based on information analyzed by the SQL analysis module and information on an input data amount and a cache amount as repetition information acquired from a job management program; and
a module for instructing prefetching which issues the prefetching method determined by the prefetching method determination module to the storage device which constitutes an access destination.
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16. A management method which is executed in a computer system including a storage device which has a plurality of logical disk devices which store data and a cache which stores a copy of the data stored in the logical disk devices and a database management system DBMS which executes management of reading and writing of the data from the storage device, the management method comprising:
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a step for acquiring information on a prefetching job including information on a program of an object which issues a prefetching instruction and information on a DBMS constitution from the DBMS, a step for an SQL analysis for grasping a repetition group based on information on SQL statements which a job program designated by the acquired prefetching job information issues and, at the same time, for setting a structure of access data and an access method based on an execution plan of the SQL statements acquired from the DBMS;
a prefetching method determination step for determining a cache prefetching method based on information analyzed by the SQL analysis and information on an input data amount as repetition information acquired from a job management program; and
a step for instructing prefetching which issues the prefetching method determined by the prefetching method determination module to the storage device which constitutes an access destination. - View Dependent Claims (17, 18, 19, 20)
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Specification