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AssigneesHitachi, Ltd., Hitachi Software Engineering Co., Ltd.
InventorsHideaki Kasao, Keisuke Toda, Kota Yamaguchi, Kazuo Masai, Kiyomi Hirohata
Estimating the term…
A parallel database management system with a database divided into a plurality of external memory units is disclosed. A control CPU, upon receipt of a request for access to the database, decides whether the access request is for storing or searching a record. For a record storage request, the control CPU determines an external memory unit to store the record using a hash function. In the case of a record search request, on the other hand, all the external memory units are searched in parallel without using the hash function thereby to obtain the desired record. The hash function is altered upon addition of an external memory unit.
A data management method for storing data in a storage area in response to an input of a request for storing the data, comprising the steps of:
A storage area management method for storing data in a storage area in response to an input of a request for storing the data, comprising the steps of:
A data management system for storing data in a storage area in response to an input of a request for storing the data, said storage area having a first storage area, comprising;
A computer program, stored on a storage medium, for performing data management by storing data in a storage area in response to an input of a request for storing the data, said storage area having a first storage area, said computer program when executed causes a computer to perform the steps of:
Dependencies are inferred from the claim text.
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Query optimisation: of parallel queries
Data processing: database and file management or data structures: database or file accessing
Database or file accessing: query processing, i.e. searching
Database or file accessing: sorting
Term end not estimated
The present invention relates to a parallel database record distribution method and a parallel database management system, or more particular to a record distribution method and a management system capable of managing the addition of a database unit in a parallel database management system including a plurality of database units in versatile way.
Conventionally, when a large amount of records are to be distributed equally among a plurality of database units of a parallel database management system, a hash function is used in view of a high level of versatility against the increase in the number of records with a small overhead for distribution. In such a case, the hash function is used for both the preparation and addition of a record and the search of the record. In other words, when a new record which has been prepared is stored in a parallel database, the hash function is used to determine a database unit to store it in, and when searching for the desired record, the same hash function is used to determine the database unit having the record stored therein.
The hash function is used in the systems described in JP-A-2-113349, JP-A-4-160475 and JP-A-6-103127, for example.
FIG. 1 is a diagram showing a general configuration of a parallel database management system according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the record search process according to the embodiment shown in FIG. 1.
FIGS. 3A and 3D are diagrams showing a change in the contents of a control table when the hash function used in the embodiment of FIG. 1 is altered.
An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a configuration of a parallel database management system according to an embodiment of the invention.
A parallel database management system 100 shown in FIG. 1 comprises a plurality of database units A and B for storing the database records in divisions, and a central processing unit (CPU) 10 used for control. The control CPU 100 receives a database access request from an application program, determines an external memory unit of the database unit to which the access request is destined, and hands over the control to the CPU of the database unit to which the access request is destined.
The database unit A includes an external memory unit 13 for storing the record distributed thereto, and a CPU 12 for executing the search and storage of the record stored in the external memory unit 13. In similar fashion, the database unit B includes an external memory unit 15 for storing the record distributed to the particular database unit and a CPU 14 for executing the search and storage of the record stored in the external memory unit 15.