Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-05-14
2002-12-10
Breene, John (Department: 2177)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C707S793000, C709S241000, C709S248000
Reexamination Certificate
active
06493725
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a database managing system for making the same contents between parties which are ready to communicate, and particularly to a database managing system capable of reducing the amount of data transmitted or processed during a synchronous process.
BACKGROUND OF THE INVENTION
Conventionally, information processing devices have been in wide use, and it is not rare in recent years for one individual to own a plurality of information processing devices, for example, such as a high-performance information processing device like a desk-top personal computer and a portable information processing device like a portable information terminal. When personal information, for example, such as schedules and address book are to be managed by these plurality of information processing devices, there is a need to maintain the same contents of data in any of databases provided in these information processing devices. Thus, in the case of managing, for example, personal information between a personal computer and a portable information terminal, a master database is managed by the personal computer and the data of the master database are copied to the database (portable database) of the portable information processing device, thus carrying the personal information.
In this manner, when managing the same data between a plurality of database managing devices, when the data are changed in one database managing device, it is required to update the database of all the other database managing devices. Here, if each database managing device is in communications all the time, the change in data is immediately reflected in each one of these devices when the updated database managing device informs the other database managing devices that the data have been changed. However, it is not always the case that each database managing device is in communications all the time with the other devices, for example, as in the case where the database managing device is a portable information terminal. In such a case, a change in data in one device is not reflected in the databases of the other database managing devices at the time when the change is made. Thus, in order to maintain the same database, it is required to carry out a process for making the same contents of database between parties at the time when communications are made between the database managing devices; namely, a synchronous process is required.
In the case of the above example, when data are changed in the portable information terminal, a synchronous process is carried out at the time when the portable information terminal is brought back to home or office, in which the data become the same between the portable database of the portable information terminal and the master database of the computer.
As an example of a conventional synchronous process, upload and download are known. Specifically, when data are changed in the personal computer, the contents of the master database are copied to the portable information terminal (download). On the other hand, when data are changed in the portable information terminal, the contents of the portable database are copied to the personal computer (upload).
Another example is a synchronous process employing a sum of sets. In this synchronous process, the contents of the both databases are compared at the time when communications are made between the two database managing devices, and a sum of sets, which contains all the information added to each database is created as a new database. Thereafter, the database thus created is stored the both database managing devices.
For example, when the both databases initially contain data “A”, and data “B” is added to one database managing device X, and data “C” is added to the other database managing device Y, the database managing device X sends its contents “A+B” to the database managing device Y. The database managing device Y creates a sum of sets “A+B+C” of the data “A+B” received and its contents “A+C” and stores the sum of sets as a database. The database managing device Y then sends the contents of the database “A+B+C” back to the database managing device X. As a result, the contents of the database of the database managing device X are updated to “A+B+C”, which are the same as that of the database managing device Y.
However, the conventional database managing device carrying out the described synchronous process has a problem that the data amount (communications volume) transmitted between the database managing devices in the synchronous process and the data amount computed in each database managing device are extremely large.
Specifically, in download and upload, all the contents of one of the databases are transmitted to the other database managing device regardless of the number of data updated. For example, in the case of a database having the data of 1000 items, the data of all the 1000 items are sent even when only one item is changed. As a result, the communications volume transmitted between the database managing devices is increased. Further, in the database managing device on the receiving side, the contents of the database are replaced with the database on the sending side, and thus a change in data on the receiving side is lost.
Also, in the synchronous process employing a sum of sets, in order to create a sum of sets, a database of one party is sent to the other database, and the sum of sets created is sent back as a new database. Thus, in this synchronous process, all the contents of the database are required to be sent back and forth between the database managing devices, and this further increases the communications volume in the synchronous process.
Further, in the case where the data are deleted only in one of the devices, the data remain in the other device. Thus, the data are included again in a new database and are not deleted. As a result, the memory space required for storing the database is increased, and the communications volume in the synchronous process is further increased.
In order to solve these problems, another example of the synchronous process is disclosed, for example, in Japanese Unexamined Patent Publication No. 6693/1997 (Tokukaihei 9-6693), in which update information indicative of a change or no change in data is given to all the data contained in the database. Specifically, each database managing device stores, per each data stored in the database, ID information for identifying the data and update information indicative of no change/correction/addition/deletion, and when the data are changed, the update information corresponding to the data is updated. Also, in the synchronous process, one database managing device informs the other database managing device the ID information and update information of all data. The database managing device on the receiving side searches through its database data corresponding to the data of the sending side based on the ID information received so as to compare the update information of the both sides. When a change is made only on one side, unchanged data are replaced with the data changed. When there is a change on the both sides, the data of one party are added to the database of the other party, and vice versa. With this arrangement, in the case where there is no change of data in any of the database managing devices, sending of such data can be omitted, thus reducing the communications volume in the synchronous process.
Even so, with the above arrangement, when correction of data is made on the both sides, the data corrected in one device are added to the other database, and vice versa, and the number of data contained in the database is increased. As a result, the memory space required for storing the database is increased, resulting in an increase in communications volume. Further, in order to suppress an increase in the number of data, it is required to delete unnecessary data after the synchronous process. However, this operation is troublesome because it is required to extract data to
Fujita Fusayuki
Iwai Toshiyuki
Kamakura Kazushi
Nakagawa Kanji
Takizawa Hidetoshi
Lewis Cheryl
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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