Hitachi, Ltd.

Other

Takeo Maruyama

Satoshi Wakayama

Yoichi Yamamoto

Hitoshi Tanaka

Norifumi Nishikawa

Kazuhiro Satoh

Hideyuki Takatani

Hiroyuki Yanaka

Hideo Munetika

Yo-ichi Yamamoto

A system for managing an object-oriented database in response to a request issued from an application program includes a database for storing therein both of a class having a definition of an object and an object generated from the class; a generating unit 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; another generating unit for generating an object to store an attribute value corresponding to the class definition information in accordance with the class definition information, the object generating unit including a-storage control unit for storing the attribute value related to a normal attribute into one storage unit area of the database when the request issued from the application program is related to the normal attribute, and for storing the attribute value related to a clustering attribute into another storage unit area of the database when the request issued from the application program is related to a clustering attribute; and acquiring unit for acquiring information corresponding to an identifier of an attribute required by the application program from any one of the one storage unit area and the another storage unit area, and for storing the acquired information into a memory area.

Method and system for managing object-oriented database

In a distributed database system including a plurality of database systems each having a database, wherein a database possessed by one of the database systems serves as an original database, and databases of the remaining database systems are produced by replicating the original database, the presence or absence of update contention of the same data in two database systems is detected. When data susceptible to detection of update contention is updated, an update serial number is produced for the data. The update serial number includes a system identifier for identifying a database system in which the data is updated and an update frequency related to the number of times of updates. The update serial number is accumulatively stored in an update serial number history associated with the data each time the data is updated. When the updated data and the update serial number history associated therewith are transferred to a receiving database system, the contents of the update serial number history associated with the received data is compared with the contents of an update serial number history associated with data corresponding to the received data (target data) in a database of the receiving database system, and a contending state of the received data with the target data is determined based on the result of the comparison in the receiving database system.

Distributed database system and method of detecting contention in data

In an object extending method for use in an object-oriented data base system having an object having an attribute, a relation and a procedure and a definition object having definition information determining a structure of the object, information on changes in attribute, relation and procedure which accompany a change in the definition object is held as a parts object in the definition object, and data to be newly appended to the object as a result of the change in the definition object is held as a parts object in the object, so that work to change the object in accordance with a change in schema may be reduced.

Object extending method

An object-oriented system which deals with data and procedure integrally includes a memory having a real memory space which contains a set of object management information, a set of page management information, a fixed page region and an unfixed page region, a memory management section for managing these parts, a swap file for saving pages, and a method execution section which executes the procedure of an object. When loading the object into the real memory space, address-unfixed pages in the unfixed page region are allotted to the object and address-fixed pages in the fixed page region are allotted to the object at the time of execution. Consequently, the object can be accessed directly based on the physical address. The garbage collection and page swapping processes are implemented only for address-unfixed pages, and the overhead of object access operation can be reduced.

Memory management technique for efficient execution of procedures in

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Osaka, Japan

Takeo Maruyama