Optimization of change log handling

Details Optimization of change log handling Optimization of change log handling

1999-10-27

2003-02-04

Corrielus, Jean M. (Department: 2172)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C707S793000, C707S793000, C707S793000, C714S020000

Reexamination Certificate

active

06516314

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates in general to the field of communications, and in particular, to optimizing synchronization procedures which utilize a change log to thereby increase efficiency of information synchronization between associated devices.
2. Description of Related Art
Handheld organizers, such as personal digital assistants, have become increasingly popular in our modern, information-rich society. These small, portable devices enable users to conveniently store and maintain such information as contacts, phone books, calendars, task lists, etc. and allow users to synchronize the stored information with a similar handheld organizer or with another computing device which emulates the appropriate hardware or software protocols. The synchronization process allows users to add, modify or delete information at a first device and synchronize the added, modified or deleted information with a second device so that both devices contain the same information. With the recent incorporation of handheld organizers, or at least features thereof, into wireless communication devices, such as mobile phones and pagers, and the addition of wireless interfaces to conventional handheld organizers, the synchronization process has become easier and more convenient by allowing users to synchronize information stored at associated devices via a wireless interface.
The convenience and, efficiency of information synchronization has been further enhanced through the use of change log handling. A change log is typically a register or group of records which store a log of changes made to one of the associated databases. For example, a change log associated with a first database stores and maintains information associated with changes made to records of the first database. During a synchronization procedure, the change log is utilized by a synchronization apparatus to process only those changes that are contained in the change log. Consequently, the change log significantly increases the efficiency of information synchronization by avoiding the necessity of comparing each record contained in the first database with each corresponding record contained in a second database in order to maintain a one-to-one relationship between the two databases.
One significant problem associated with this approach is that the change log is stored and maintained only at the first database which forces the synchronization apparatus to request a transfer of the entire change log in response to initiation of a synchronization procedure. Because the synchronization apparatus must process changes at the second database in the same order in which the changes were made to the first database, the synchronization apparatus must read the entire change log to identify the oldest entries of the change log (e.g., the oldest changes of the first database). This procedure can be time-consuming depending on the size of the change log.
Another significant problem is that existing approaches do not define how the change log should be optimally transferred to the synchronization apparatus, the order in which the change log should be optimally processed by the synchronization apparatus, and how the synchronization apparatus should proceed when an interruption occurs during the transfer of the change log. For example, a typical transfer begins with the first byte of the change log, and ends with the last byte of the change log. If an interruption occurs during the transfer, the synchronization apparatus will not receive the oldest entries of the change log, and it therefore cannot begin processing the entries of the change log at the second database. Consequently, an interruption in the transfer of the change log forces the synchronization apparatus to request re-transmission of the entire change log after a connection to the first database is restored. This procedure further decreases the efficiency of information synchronization.
Therefore, in light of the deficiencies of existing approaches, there is a need for a method and apparatus that optimizes synchronization procedures which utilize a change log to thereby increase the efficiency of information synchronization.
SUMMARY OF THE INVENTION
The deficiencies of the prior art are overcome by the method and system of the present invention. For example, as heretofore unrecognized, it would be beneficial to optimize information synchronization between a first device and a second device by increasing the efficiency of change log handling. For example, in accordance with one aspect of the present invention, the second device stores a change counter value associated with a last synchronized entry of a change log stored at the first device. A portion of the change log containing entries occurring after a submitted change counter value is preferably transferred from the first device to the second device in a predetermined order so as to avoid restarting the synchronization procedure in the event an interruption in the transfer of the change log occurs. Also, the change counter value stored at the second device is preferably updated after each entry of the transferred change log is processed at the second device and in response to database updates performed at the first device.
In a first embodiment, a current change counter is stored at a first device, and is updated at the first device in response to a database update command from a second device. The first device then returns the updated change counter to the second device in response to a processing condition resulting from the database update command at the first device. The updated change counter can be included in, for example, a confirmation message to the second device. The confirmation message can inform the second device of the current change counter, the unique identification (UID) of the record at the first device and a status of the database update command. The second device may then store the returned change counter for use in a subsequent synchronization procedure or in the event an interruption or other error occurs, without having to read the entire change log.
In a second embodiment, the second device submits a stored change counter to the first device in response to initiation of a synchronization procedure, and the first device transfers to the second device entries of the change log occurring after the submitted change counter. The entries of the change log are preferably transferred to the second device in reverse order (e.g., with the oldest entries of the change log first). The second device also preferably processes the oldest entries of the change log first, and updates the change counter stored at the second device after each entry is processed. As a result, the second device can avoid restarting the synchronization procedure in the event an interruption occurs, and can start performing updates in accordance with the received entries of the change log, even though only a portion of the transferred change log is actually received.
The technical advantages of the present invention include, but are not limited to, the following exemplary technical advantages. It should be understood that particular embodiments may not involve any, much less all, of the following exemplary technical advantages.
An important technical advantage of the present invention is that it increases the efficiency of change log handling by ensuring that the second device maintains the current change counter.
Another important technical advantage of the present invention is that it enables the second device to process change log entries despite an interruption in the transfer of the change log.
Yet another important technical advantage of the present invention is that it allows the second device to begin processing the change log even when only a portion of the change log is actually received.
Yet still another important technical advantage of the present invention is the ability to improve the efficiency of synchronization procedures which utilize a change log by optimizing change log

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