Asynchronous replication of data changes by distributed update requests

• US 5,261,094 A
• Filed: 04/08/1991
• Issued: 11/09/1993
• Est. Priority Date: 04/08/1991
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Robertson, Boyd D., Everson, Rhonda S., Felix, Michael R.
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): AMSBURY, WAYNE P
• Application Number:
  US07/682,041
• Time in Patent Office: 946 Days
• Field of Search: 364/900 MS File, 364/200 MS File, 364/300 MS, 395/600 MS
• US Class Current: 1/1
• CPC Class Codes: G06F 15/161 Computing infrastructure, e.g. computer clusters, blade chassis or hardware partitioning casings, cabinets, racks or drawers for data centers H05K5/00
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

A method of replicating changes made to databases distributed throughout a computer network is described. A first program (TP1) in the Collector node instructs a second program (TP2) in the Collectee node to send all updates to a database since the last conversation. TP2 processes queries to retrieve any changes made since the last conversation between the Collector and Collectee nodes and send the data to TP1, which updates the copy of the database on its own system.

Claims

1. In a distributed computing environment, which includes a plurality of computers, each of which include at least one relational database and a control table, a method for replicating changes to one of the databases comprising the steps of:

(a) periodically initiating an update conversation between a first computer and a second computer;

(b) said first computer instructing said second computer to send to the first computer only all changes to its database since the last update conversation;

(c) said second computer processing said instruction, preparing an update, and transmitting the update along with a time of transmission to the first computer, and updating the control table of said second computer with said transmission time;

(d) said first computer receiving the said update and the said time of transmission and replicating all said changes in its database; and

(e) said first computer updating its control table with said time of transmission of the said update.

2. The method as claimed in claim 1 wherein the computers communicate in a peer to peer relationship.

3. The method as claimed in claim 1 wherein the computers are arranged in a hierarchical relationship.

4. The method as claimed in claim 1 wherein said initiating step is performed at predefined time intervals.

5. The method as claimed in claim 1 wherein the second computer processing said instruction step includes preparing a data query in a structured query language format.

6. The method as claimed in claim 1 wherein the control table of each computer includes the time of the last update to the said relational database contained in said computer.

7. A method for maintaining identical information in a plurality of relational databases distributed in a plurality of computer systems comprising the following steps:

(a) periodically triggering a first computer process in a first computer system which initiates an update conversation with a second computer process in a second computer system;

(b) said first computer process instructing said second computer process to query its database and identify only all changes made to its information since the last update conversation of its information was sent to said first computer process;

(c) said second computer process querying its database, preparing the update, transmitting only the updated information along with a time of transmission to said first computer process, and updating the control table of said second computer system with said transmission time;

(d) said first computer process receiving the updated information and said time of transmission and applying the said updated information to its database; and

(e) said first computer process updating its control table with the said time of the last update transmitted by the second computer process.

8. The method as claimed in claim 7 wherein the computer systems communicate in a peer to peer relationship.

9. The method as claimed in claim 7 wherein the computer systems are arranged in a hierarchical relationship.

10. The method as claimed in claim 7 wherein the control tables of each computer system include the times of last update to the relational databases contained in said each computer system.