Distributed synchronization of databases

Details Distributed synchronization of databases Distributed synchronization of databases

1999-11-30

2001-04-24

Homere, Jean R. (Department: 2177)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C709S201000, C709S248000

Reexamination Certificate

active

06223187

ABSTRACT:

REFERENCE TO MICROFICHE APPENDIX
An appendix (appearing now in paper format to be replaced later in microfiche format) forms part of this application. The appendix, which includes a source code listing relating to an embodiment of the invention, includes 153 frames on 2 microfiche.
This patent document (including the microfiche appendix) contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND
This invention relates to synchronizing databases.
Databases are collections of data entries which are organized, stored, and manipulated in a manner specified by applications known as database managers (hereinafter also referred to as “Applications”; the term “database” will also refer to the combination of a database manager and a database proper). The manner in which database entries are organized in a database is known as its data structure.
There are generally two types of database managers. First are general purpose database managers in which the user determines (usually at the outset, but subject to future revisions) what the data structure is. These Applications often have their own programming language and provide great flexibility to the user. Second are special purpose database managers that are specifically designed to create and manage a database having a preset data structure. Examples of these special purpose database managers are various scheduling, diary, and contact manager Applications for desktop and handheld computers. Database managers organize the information in a database into records, with each record made up of fields. Fields and records of a database may have many different characteristics depending on the database manager's purpose and utility.
Databases can be said to be incompatible with one another when the data structure of one is not the same as the data structure of another, even though some of the content of the records is substantially the same. For example, one database may store names and addresses in the following fields: FIRST_NAME, LAST_NAME, and ADDRESS. Another database may, however, store the same information with the following structure: NAME, STREET_NO., STREET_NAME, CITY_STATE, and ZIP. Although the content of the records is intended to contain the same kind of information, the organization of that information is completely different.
Often users of incompatible databases want to be able to synchronize them with one another. For example, in the context of scheduling and contact manager Applications, a person might use one Application on the desktop computer at work while another on his handheld computer or his laptop computer while away from work. It is desirable for many of these users to be able to synchronize the entries on one with entries on another. The U.S. patent and copending patent application of the assignee hereof, Puma Technology, Inc. of St. Jose, Calif. (U.S. Pat. No. 5,392,390 (hereinafter, “the '390 patent”); U.S. application, Ser. No. 08/371,194, filed on Jan. 11, 1995, incorporated by reference herein) show two methods for synchronizing incompatible databases and solving some of the problems arising from incompatibility of databases.
Synchronization of two incompatible databases often requires comparison of their records so that they can be matched up prior to synchronization. This may require transferring records in one database from one computer to another. However, if the data transfer link between the two computers is slow, as for example is the case with current infrared ports, telephone modem, or small handheld computers, such a transfer increases the required time for synchronization by many folds.
SUMMARY
In one aspect, the invention features a computer implemented method for synchronizing a first database located on a first computer and a second database located on a second computer. At the first computer, it is determined whether a record of the first database has been changed or added since a previous synchronization, using a first history file located on the first computer comprising records representative of records of the first database at the completion of the previous synchronization. If the record of the first database has not been changed or added since the previous synchronization, the first computer sends the second computer information which the second computer uses to identify the record of the first database to be unchanged.
The embodiments of this aspect of the invention may include one or more of the following features.
A second history file may be located on the second computer. The second history file contains records representative of records of the first database at the completion of the previous synchronization, where one of the representative records represents the record of the first database determined to be unchanged. Then, at the second computer, a synchronization of the second and first databases is performed using the one of the representative records.
The information sent from the first computer to the second computer can be used to locate the one of the representative records in the second history file. The second history file can store information in relation to the representative records and the one of the representative records in the second history file can be identified from that stored information. Additionally, the information sent from the first computer to the second computer can include information that matches the information stored in relation to the one of the representative records in the second history files.
The information sent to the second computer can include information identifying records other than the unchanged record. It can also include information identifying the changed record. It can also include information identifying the deleted records or added records. The information can also include a code based on at least a portion of the content of the record of the first database. The code may be a hash number. The information may be a code uniquely identifying the record of the first database. Such a code may be one assigned by the first database to the records.
In another aspect, the invention features a computer implemented method of identifying a record of a database. A record of the database is read. A code is assigned to the record of the database, the code being based on at least a portion of the content of the record of the first database. The code is then to identify the record at a later time.
The embodiments of this aspect of the invention may include one or more of the following features.
The code may be a hash number computed based on at least a portion of the content of a record of the first database.
The database is stored on a first computer and the code is transmitted. to a second computer to identify the record to an application.
Advantages of the invention may include one or more of the following advantages.
When synchronization is performed using the invention, a data transfer link, specially a slow data transfer link, is used efficiently, since unchanged records that are typically the majority of the records in a database are not transferred between the two computers. Hence, when synchronizing two databases on two different computers, the time needed to synchronize the two databases is decreased
Also, when transmitting data from one computer to another, using a content based code, that requires less bandwidth for being transmitted and nonetheless identifies a record, results in a slow data transfer links being used more efficiently.
The invention may be implemented in hardware or software, or a combination of both. Preferably, the technique is implemented in computer programs executing on programmable computers that each include a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one outp

Affiliated with

Also associated with

Rating

Distributed synchronization of databases does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Distributed synchronization of databases, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Distributed synchronization of databases will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2464984