Accumulating changes in a database management system by copying the data object to the image copy if the data object identifier of the data object is greater than the image identifier of the image copy

• US 6,161,109 A
• Filed: 04/16/1998
• Issued: 12/12/2000
• Est. Priority Date: 04/16/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Matamoros, Deborah A., Ruddy, James Alan
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): JUNG, DAVID YIUK
• Application Number:
  US09/061,589
• Time in Patent Office: 971 Days
• Field of Search: 707/1-206
• US Class Current: 1/1
• CPC Class Codes: G06F 16/219 Managing data history or versioning querying versioned data G06F16/2474; querying temporal data G06F16/2477
• CPC Class Codes: G06F 16/2282 Tablespace storage structures; Management thereof
• CPC Class Codes: G06F 16/2308 Concurrency control transaction processing G06F9/466
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

A method, apparatus, and article of manufacture for a computer implemented image copying system for identifying modifications in a database in a computer. The database contains data objects and is stored on a primary data storage device connected to the computer. A data object identifier is generated for each data object as the data object is modified. An image identifier is generated for an image copy of the database when the image copy is updated, wherein the image copy is stored on a secondary data storage device. When one or more data objects are to be copied from the primary data storage device to the secondary data storage device, the data objects to be copied are determined by comparing the data object identifier of each data object to the image identifier.

Claims

1. A method of identifying modifications in a database in a computer, the database containing data objects and being stored on a primary data storage device connected to the computer, the method comprising the steps of:

generating a different data object identifier for each data object as the data object is modified, wherein the data object identifier reflects when the data object is modified;

generating a different image identifier for an image copy of the database when the image copy is updated, wherein the image identifier reflects when the image copy is updated, and wherein the image copy is stored on a secondary data storage device; and

when one or more data objects are to be copied from the primary data storage device to the secondary data storage device, only comparing the data object identifier to the image identifier and, if the data object identifier of the data object is greater than the image identifier of the image copy, copying the data object to the image copy.

2. The method of claim 1, wherein a data object is a record of the database.

3. The method of claim 1, wherein a data object is a block of records of the database.

4. The method of claim 1, wherein the data object identifier is based on a global sequence number.

5. The method of claim 1, wherein the image identifier is based on a global sequence number.

6. The method of claim 1, further comprising:

determining that a full image copy is to be made;

copying each data object in the database from the primary data storage device to the image copy on the secondary data storage device;

updating the image identifier of the image copy on the secondary data storage device; and

updating the image identifier of the image copy in a system catalog.

7. The method of claim 1, further comprising the step of determining that a partial image copy is to be made.

8. An apparatus for identifying modifications in a database, comprising:

a computer having a primary data storage device connected thereto, wherein the primary data storage device stores the database which contains data objects;

one or more computer programs, performed by the computer, for generating a different data object identifier for each data object as the data object is modified, wherein the data object identifier reflects when the data object is modified, generating a different image identifier for an image copy of the database when the image copy is updated, wherein the image identifier reflects when the image copy is updated, and wherein the image copy is stored on a secondary data storage device, and when one or more data objects are to be copied from the primary data storage device to the secondary data storage device, only comparing the data object identifier to the image identifier and, if the data object identifier of the data object is greater than the image identifier of the image copy, copying the data object to the image copy.

9. The apparatus of claim 8, wherein a data object is a record of the database.

10. The apparatus of claim 8, wherein a data object is a block of records of the database.

11. The apparatus of claim 8, wherein the data object identifier is based on a global sequence number.

12. The apparatus of claim 8, wherein the image identifier is based on a global sequence number.

13. The apparatus of claim 8, further comprising:

means for determining that a full image copy is to be made;

means for copying each data object in the database from the primary data storage device to the image copy on the secondary data storage device;

means for updating the image identifier of the image copy on the secondary data storage device; and

means for updating the image identifier of the image copy in a system catalog.

14. The apparatus of claim 8, further comprising the means for determining that a partial image copy is to be made.

15. An article of manufacture comprising a computer program carrier readable by a computer and embodying one or more instructions executable by the computer to perform method steps for identifying modifications in a database, the database containing data objects and being stored on a primary data storage device connected to the computer, the method comprising the steps of:

generating a different data object identifier for each data object as the data object is modified, wherein the data object identifier reflects when the data object is modified;

generating a different image identifier for an image copy of the database when the image copy is updated, wherein the image identifier reflects when the image copy is updated, and wherein the image copy is stored on a secondary data storage device; and

when one or more data objects are to be copied from the primary data storage device to the secondary data storage device, only comparing the data object identifier to the image identifier and, if the data object identifier of the data object is greater than the image identifier of the image copy, copying the data object to the image copy.

16. The article of manufacture of claim 15, wherein a data object is a record of the database.

17. The article of manufacture of claim 15, wherein a data object is a block of records of the database.

18. The article of manufacture of claim 15, wherein the data object identifier is based on a global sequence number.

19. The article of manufacture of claim 15, wherein the image identifier is based on a global sequence number.

20. The article of manufacture of claim 15, further comprising:

determining that a full image copy is to be made;

copying each data object in the database from the primary data storage device to the image copy on the secondary data storage device;

updating the image identifier of the image copy on the secondary data storage device; and

updating the image identifier of the image copy in a system catalog.

21. The article of manufacture of claim 15, further comprising the step of determining that a partial image copy is to be made.