Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1995-07-21
2001-01-30
Alam, Hosain T. (Department: 2771)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C707S793000
Reexamination Certificate
active
06182082
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a database management system, more specifically, to a technique suitably applied to an object-oriented database management system.
It should be noted that the present invention is related to the co-pending U.S. pat. application Ser. No. 08/038, 634, entitled “OBJECT MANAGEMENT SYSTEM” filed by T. Maruyama et al., on Mar. 29, 1993, now pat. no. 5,526,519.
In the conventional object-oriented database management system, an object corresponds to a data set containing an object identifier for exclusively indicating the object, a length of the object, the attribute number, attribute information, attribute data, and an offset for storing attribute data.
As to the above-described technique, Wom Kim; “Introduction to Object-Oriented Database”, The MIT press, 1992, pages 107 to 114 describes such an object, class, instance and clustering.
Then, in the conventional object-oriented database management system, the database is subdivided into several physical regions called as “partitions”, a plurality of segments each containing several storage regions referred to “pages” are formed on each of these partitions, and such objects under one relationship are stored in one of these storage regions for management purpose, paying attention to a plurality of objects having a common attribute, a plurality of objects belonging to the different class and having the common attribute, or a part of an object.
Normally, an object having either the common attribute, or a dependent attribute with respect to the data about one attribute of the object, the attribute defining one character of the object, stored in the same storage region can be read out with one accessing operation together with the one attribute, giving a merit in performance.
The Applicants of the present invention could find out the following problems by investigating the above-described prior art.
That is, the above-mentioned prior art does not consider to obtain data of one or a plurality of selected common attributes among a plurality of objects within one time. In order to acquire the data with one attribute of the plural objects within one time, all of these plural objects arranged at the physically adjacent locations are first acquired, and then the attribute data should be selected in accordance with the offset of the attribute data and the attribute information owned by the object.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a technique capable of acquiring a data portion selected from data about attributes of a class.
Another object of the present invention is to reduce an overhead for acquiring a portion of attribute data, after obtaining data of whole objects, in accordance with attribute information of each object.
The above-described objects and other objects and also novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.
A system for managing an object-oriented database in response to a request issued from an application program, comprising:
a database for storing therein both of a class having a definition of an object and an object generated from said class;
means for generating a class and a plurality of attributes based on class definition information and attribute definition information, which are designated by the application program;
means for generating an object storing therein an attribute value corresponding to said class definition information in accordance with said class definition information, said object generating means including a storage control unit for storing the attribute value related into one storage unit area of said database when the request issued from the application program is related to a normal attribute, and for storing the attribute value related to said clustering attribute into another storage unit area of said database when the request issued from the application program is related to a clustering attribute; and
means for acquiring information corresponding to an identifier of an attribute required by the application program from any one of said one storage unit area and said another storage unit area, and for storing the acquired information into a memory area.
An attribute value corresponding to the identifier of the attribute required by the application program will be acquired by the application program.
Such an object-oriented database management system may be constructed which comprises a class having a definition of an object, a database for storing therein an object generated from this class, a management means for managing the database, an dictionary service unit for managing the object and the definition information about the attribute data; the storage control unit for storing either the attribute data for each of the same classes from the definition information, or the attribute data common to the plural classes into the same storage area within the database; and the object management unit for deriving this attribute data from the storage control unit in the same storage region unit and for transferring the derived attribute data to the application program within one accessing operation.
According to the above-described arrangement, in the object-oriented database management system, there are provided the dictionary service unit for managing the object and the definition information about the attribute data; the storage control unit for storing either the attribute data for each of the same classes from the definition information, or the attribute data common to the plural classes into the same storage area within the database; and the object management unit for deriving this attribute data from the storage control unit in the same storage region unit and for transferring the derived attribute data to the application program within one accessing operation. When the attribute data of the class is acquired within one accessing operation, it is no longer required that all of the objects are acquired, and then the attribute data is acquired in accordance with the attribute information owned by the object and also the offset of the attribute data. In other words, since the data stored in the same storage area is merely acquired, all of the attribute data about the object of the class within the database can be acquired at once. Accordingly, the attribute data acquisition efficiency can be increased.
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Jones et al. “The OKS persistent in memory object manager” IEEE transactions on nuclear science, vol. 45, No. 4, pp. 1958-1964, Aug. 1998.
Goto et al., “A deductive objected language for Integrated”, IEEE, pp. 108-109, 1994.
Urban et al., “The implementation and evaluation of integrity Maintenance Rules in an object-oriented database”, IEEE, pp. 565-572, 1992.
Maruyama Takeo
Munetika Hideo
Tanaka Hitoshi
Wakayama Satoshi
Yamamoto Yo-ichi
Alam Hosain T.
Antonelli Terry Stout & Kraus LLP
Corrielus Jean M.
Hitachi , Ltd.
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