Method and apparatus for synchronizing multiple copies of a database

• US 5,970,502 A
• Filed: 04/23/1996
• Issued: 10/19/1999
• Est. Priority Date: 04/23/1996
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Corporation
• Inventors: Callon, Ross W., Salkewicz, William M.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): RONES, CHARLES
• Application Number:
  US08/636,664
• Time in Patent Office: 1,274 Days
• Field of Search: 395/617, 395/182.14, 395/250, 395/608, 395/618, 395/672, 395/620, 395/601, 395/614, 395/182.04, 379/45, 707/201, 707/8, 707/10, 707/104, 707/203
• US Class Current: 1/1
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method for synchronizing a first database with a second database in which the first database contains a plurality of database records. The first database is divided into a plurality of segments. Each of the segments contains at least one database record. The segments are transmitted sequentially from the first database to the second database until all segments have been transmitted to the second database.

Claims

1. A method for synchronizing a first database with a second database, wherein said first database contains a plurality of database records, said method comprising the steps of:

lexically dividing said first database into a plurality of segments; and

sequentially transmitting each segment from said first database to said second database until all segments are transmitted to said second database for storage in said second database, wherein segments not in current transmission may be modified.

2. The method of claim 1 wherein said step of sequentially transmitting each segment includes copying each segment to a storage device and transmitting said segment copy from said storage device to said second database.

3. The method of claim 2 wherein said storage device is a memory device capable of storing at least one segment.

4. The method of claim 2 wherein said storage device is a disk storage device capable of storing at least one segment.

5. The method of claim 2 further including the step of preventing modification of database records currently being copied to said storage device.

6. The method of claim 1 further including the step of awaiting an acknowledgement from said second database after transmitting each segment to said second database.

7. The method of claim 1 further including the step of permitting modification of database records in said first database after said database records have been transmitted to said second database.

8. The method of claim 1 further including the step of permitting modification of database records in said first database before said database records have been transmitted to said second database.

9. The method of claim 1 wherein said first database is located on a first server and said second database is located on a second server, said first and second servers coupled to one another through a communication medium.

10. The method of claim 1 wherein said first database is arranged in a lexical order.

11. The method of claim 1 wherein each segment contains a plurality of database records from said first database.

12. A method for synchronizing a first database with a second database, wherein said first database contains a plurality of database records, said method comprising the steps of:

a) lexically dividing said first database into a plurality of segments, wherein each segment contains at least one database record;

b) sequentially copying each segment from said first database to a storage device;

c) transmitting said copy of said segment from said storage device to said second database for storage in said second database, wherein segments not in current transmission may be modified; and

d) repeating steps b) and c) until all segments are transmitted to said second database.

13. The method of claim 12 further including the step of awaiting an acknowledgement from said second database after transmitting said copy of said segment to said second database.

14. The method of claim 12 further including the step of permitting modification of database records in said first database after said database records have been transmitted to said second database.

15. The method of claim 12 further including the step of permitting modification of database records in said first database before said database records have been transmitted to said second database.

16. The method of claim 12 further including the step of preventing modification of database records currently being copied to said storage device.

17. A method for synchronizing a first database with a second database, wherein said first database contains a plurality of database records, said method comprising the steps of:

lexically dividing said first database into a plurality of segments, wherein each segment contains instance identification of at least one database record, said portion of said record containing instance identification information for determining whether said second database contains a current copy of said record;

sequentially transmitting each segment from said first database to said second database for storage in said second database, wherein segments not in current transmission may be modified; and

marking an entire database record from said first database for update if a second database contains an obsolete version of the database record.

18. The method of claim 17 wherein said step of sequentially transmitting each segment includes copying each segment to a storage device and transmitting said segment copy from said storage device to said second database.

19. The method of claim 17 further including the step of awaiting a response from said second database after transmitting each segment to said second database, said response indicating whether said second database contains a current copy of said record.

20. A method for synchronizing a first database and a second database, wherein each database contains a plurality of database records, said method comprising the steps of:

lexically dividing said first database into a plurality of segments;

lexically dividing said second database into a plurality of segments; and

sequentially transmitting each respective segment between said first and second database such that segments not in current transmission may be modified, wherein said respective segments from each of said databases synchronize each respective outdated database simultaneously, the respective segments being stored on respective databases.

21. The method of claim 20 wherein said step of sequentially transmitting each segment between said first and second databases includes copying each segment to a storage device and transmitting said segment copy from said storage device.

22. The method of claim 20 wherein said first database updates said second database if said first database contains a current copy of a particular record and said second database contains an obsolete copy of the particular record.

23. An apparatus for synchronizing a first database with a second database, wherein said first database contains a plurality of database records, said apparatus comprising:

means for lexically dividing said first database into a plurality of segments, wherein each segment contains at least one database record;

a storage device capable of receiving a copy of at least one segment; and

means for sequentially transmitting said plurality of segments from said storage device to said second database for storage in said second database, wherein segments not in current transmission may be modified.

24. The apparatus of claim 23 wherein said first database is located on a first server and said second database is located on a second server, said first and second servers coupled to one another via a communication medium.

25. The apparatus of claim 23 wherein said storage device is a memory device capable of storing at least one segment.