Capturing data changes utilizing data-space tracking

• US 20060074951A1
• Filed: 12/07/2005
• Published: 04/06/2006
• Est. Priority Date: 07/19/2002
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Watts, Vern L., Beier, Harley A.
• GRANTED PATENT: US 7,502,800 B2
• Time in patent office: 0 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2282 Tablespace storage structures; Management thereof
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

An on-line reorganization facility (ORF) uses index data-spaces that point to other data-spaces, referred to as data data-spaces, to efficiently track and coordinate information about the data-elements in an original data-space operated upon by a reorganization process. A relative base address of a data-element in an index data-space can be derived from a relative base address of a data-element in an original data-space, and vice versa. An index data-space data-element contains a location of a data-element in a data data-space that tracks change information related to a corresponding data-element in the original data-space. Tracked changes are later applied to the newly reorganized data-space to assure consistency and integrity of the data. Tracked changes include the location in the original data-space where the change occurred and a flag indicting the type of change.

Claims

1. A method of reorganizing a database and concurrently providing access to the database for updates, the database including an original data-space having a plurality of original data-elements and a shadow data-space having a plurality of shadow data-elements, the method comprising:

copying contents of an original data-element within the original data-space to a shadow data-element within the shadow data-space;

reorganizing the shadow data-space;

keeping track of a location of an original data-element that is changed after its contents are copied to the shadow data-element; and

copying data from the location of the changed original data-element to its corresponding shadow data-element in the reorganized shadow data-space.

2. A method of reorganizing information in a computer system having an original data-space that contains a plurality of sequentially stored original data-elements, a shadow data-space that contains a plurality of shadow data-elements, a data data-space that contains a plurality of data data-elements, and an index data-space that contains a plurality of sequentially stored index data-elements, wherein the original data-space is operated on by an information reorganizing application program, the method comprising:

copying contents of an original data-element within the original data-space to a shadow data-element within the shadow data-space;

recording a location of the original data-element and a location of the shadow data-element within a data data-element within the data data-space, thereby associating the original data-element, the shadow data-element and the data data-element;

recording a location of the data data-element within an index data-element within the index data-space, wherein the index data-elements in the index data-space are arranged in the same sequence as their associated original data-elements in the original data-space;

recording in the data data-element information indicating that a change has occurred in the original data-element associated with the data data-element; and

applying the change in the original data-element to the shadow data-element associated with the original data-element, in response to detecting the change associated with the original data-element recorded in the data data-element.

3. The method of claim 2, wherein said recording in the data data-element information indicating that a change has occurred in the original data-element, further comprises:

intercepting a log request that indicates the change to the original data-element;

determining a location of the changed original data-element; and

updating the data data-element associated with the changed original data-element to record the information indicating that a change occurred and to record a type of change that occurred.

4. The method of claim 3, wherein if the log request indicates that the change is an addition of a new original data-element to the original data-space, the method further comprises:

adding the data data-element to the data data-space and storing a location of the original data-element within the data data-element; and

recording a location of the data data-element within the index data-element in the index data-space, wherein the index data-elements in the index data-space are arranged in the same sequence as their associated original data-elements in the original data-space.

5. The method of claim 3, wherein the data data-element is updated to record information indicating that the original data-element has been at least one of added, updated and deleted.

6. The method of claim 2, wherein said applying the change in the original data-element to its associated shadow data-element, comprises at least one of:

adding the shadow data-element to said shadow data-space and storing a location of the shadow data-element within the data data-element, if the data data-element indicates that the original data-element was added to the original data-space;

copying the contents of the original data-element to the shadow data-element by locating the original data-element and shadow data-element from the location information recorded in the data data-element, if the data data-element indicates that the original data-element was one of updated and added; and

deleting the shadow data-element by locating the shadow data-element from the location information recorded in the data data-element, if the data data-element indicates that the original data-element located at the original data-element location stored within the data data-element was deleted.

7. The method of claim 2, wherein the index data-space and data data-space are stored in non-persistent storage.

8. The method of claim 2, wherein the index data-space and data data-space are stored in persistent storage.

9. The method of claim 2, wherein the location of the original data-element recorded in the data data-element includes a sequential position of the original data-element within the original data-space.

10. The method of claim 2, wherein the location of the original data-element recorded in the data data-element includes an offset of the original data-element from a base address of the original data-space.

11. The method of claim 2, wherein the location of the data data-element recorded in the index data-element is determined by multiplying a sequential position of the data data-element within the data data-space by a bit length of the plurality of data data-elements within the data data-space.

12. The method of claim 2, wherein the location of the data data-element within the data data-space is determined by dividing a relative base address of the data data-element by a bit length of the plurality of data data-elements within the data data-space.

13. The method of claim 2, wherein the original data-space contains a plurality of original data-elements of a first bit length and the index data-space contains a plurality of index data-elements of a second bit length.

14. The method of claim 13, wherein the first bit length and the second bit length are the same length.

15. The method of claim 13, wherein a location of the index data-element is determined from the location of its associated original data-element by dividing the location of the original data-element by the first bit length to produce a result and multiplying the result by the second bit length.

16. The method of claim 13, wherein the location of the original data-element is determined from a location of the index data-element by dividing a relative base address of the index data-element by the second bit length to produce a result and multiplying the result by the first bit length.

17. An apparatus for reorganizing information in a computer system having an original data-space that contains a plurality of sequentially stored original data-elements, a shadow data-space that contains a plurality of sequentially stored shadow data-elements, a data data-space that contains a plurality of sequentially stored data data-elements, and an index data-space that contains a plurality of sequentially stored index data-elements, the apparatus comprising:

a reorganization module configured to copy the contents of an original data-element in the original data-space to a corresponding shadow data-element in the shadow data-space and to associate the original data-element and shadow data-element using a data data-element;

a log intercept module configured to intercept a log request concerning a change in an original data-element and to update a data data-element associated with the original data-element to indicate that a change has occurred in the original data-element; and

a pending change module configured to apply the change in the original data-element to the shadow data-element corresponding to the original data-element, in response to detecting the change recorded in the data data-element associated with the original data-element.

18. The apparatus of claim 17, wherein the log intercept module updates the data data-element to record information indicating that the original data-element has been at least one of added, updated and deleted.

19. The apparatus of claim 17, further comprising:

a utility services module coupled to the reorganization module, the log intercept module and the pending change module and configured to manage the plurality of data data-elements in the data data-space and to manage the plurality of index data-elements in the index data-space;

wherein the data data-element contains information concerning a location of the original data-element and a location of the shadow data-element, thereby creating an association between the original data-element, the shadow data-element and the data data-element;

wherein the index data-element records information concerning a location of the data data-element; and

wherein the plurality of index data-elements in the index data-space are arranged in the same sequence as the plurality of original data-elements in the original data-space.

20. The apparatus of claim 19, wherein the information concerning the locations of the original data-element and shadow data-element recorded in the data data-element includes information identifying a sequential position of those data-elements within their respective data-spaces.

21. The apparatus of claim 19, wherein the information concerning the locations of the original data-element and shadow data-element recorded in the data data-element includes information identifying offsets of those data-elements from base-addresses of their respective data-spaces.

22. The apparatus of claim 17, wherein the original data-space contains a plurality of original data-elements of a first bit length and the index data-space contains a plurality of index data-elements of a second bit length.

23. The apparatus of claim 22, wherein the first bit length and the second bit length are the same length.

24. The apparatus of claim 17, wherein the index data-space and data data-space are stored in non-persistent storage.

25. The apparatus of claim 17, wherein the index data-space and data data-space are stored in persistent storage.

26. A computer program embodied on a computer readable medium for reorganizing a database and concurrently providing access to the database for updates, the database including an original data-space having a plurality of original data-elements, a shadow data-space having a plurality of shadow data-elements, a data data-space having a plurality of data data-elements and an index data-space having a plurality of index data-elements, the method comprising:

program instructions for copying contents of an original data-element within the original data-space to a shadow data-element within the shadow data-space and associating the original data-element and shadow data-element using a data data-element;

program instructions for reorganizing the shadow data-space;

program instructions for keeping track of a location of an original data-element that is changed after its contents are copied to the shadow data-element by using the data data-element that is located using an index data-element; and

program instructions for copying data from the location of the changed original data-element to its corresponding shadow data-element in the reorganized shadow data-space.

27. A computer program embodied on a computer readable medium for reorganizing information in a computer system having an original data-space that contains a plurality of sequentially stored original data-elements, a shadow data-space that contains a plurality of shadow data-elements, a data data-space that contains a plurality of data data-elements, and an index data-space that contains a plurality of sequentially stored index data-elements, the computer program comprising:

program instructions for copying contents of an original data-element within the original data-space to a shadow data-element within the shadow data-space;

program instructions for recording a location of the original data-element and a location of the shadow data-element within a data data-element within the data data-space, thereby associating the original data-element, the shadow data-element and the data data-element;

program instructions for recording a location of the data data-element within an index data-element within the index data-space, wherein the index data-elements in the index data-space are arranged in the same sequence as their associated original data-elements in the original data-space;

program instructions for recording in the data data-element information indicating that a change has occurred in the original data-element associated with the data data-element; and

program instructions for applying the change in the original data-element to the shadow data-element associated with the original data-element, in response to detecting the change associated with the original data-element recorded in the data data-element.

28. The computer program of claim 27, wherein said program instructions for recording in the data data-element information indicating that a change has occurred in the original data-element, further comprise:

program instructions for intercepting a log request that indicates the change to the original data-element;

program instructions for determining a location of the changed original data-element; and

program instructions for updating the data data-element associated with the changed original data-element to record the information indicating that a change occurred and to record a type of change that occurred.

29. The computer program of claim 28, wherein if the log request indicates that the change is an addition of a new original data-element to the original data-space, the computer program further comprises:

program instructions for adding the data data-element to the data data-space and storing a location of the original data-element within the data data-element; and

program instructions for recording a location of the data data-element within the index data-element in the index data-space, wherein the index data-elements in the index data-space are arranged in the same sequence as their associated original data-elements in the original data-space.

30. The computer program of claim 28, wherein the data data-element is updated to record information indicating that the original data-element has been at least one of added, updated and deleted.

31. The computer program of claim 27, wherein said program instructions for applying the change in the original data-element to its associated shadow data-element, comprises at least one of:

program instructions for adding the shadow data-element to said shadow data-space and storing a location of the shadow data-element within the data data-element, if the data data-element indicates that the original data-element was added to the original data-space;

program instructions for copying the contents of the original data-element to the shadow data-element by locating the original data-element and shadow data-element from the location information recorded in the data data-element, if the data data-element indicates that the original data-element was one of updated and added; and

program instructions for deleting the shadow data-element by locating the shadow data-element from the location information recorded in the data data-element, if the data data-element indicates that the original data-element located at the original data-element location stored within the data data-element was deleted.

32. The computer program of claim 27, wherein the index data-space and data data-space are stored in non-persistent storage.

33. The computer program of claim 27, wherein the index data-space and data data-space are stored in persistent storage.

34. The computer program of claim 27, wherein the location of the shadow data-element recorded in the data data-element includes a sequential position of the shadow data-element within the shadow data-space.

35. The computer program of claim 27, wherein the location of the shadow data-element recorded in the data data-element includes an offset of the shadow data-element from a base address of the shadow data-space.

36. The computer program of claim 27, wherein the location of the data data-element recorded in the index data-element is determined by multiplying a sequential position of the data data-element within the data data-space by a bit length of the plurality of data data-elements within the data data-space.

37. The computer program of claim 27, wherein the location of the data data-element within the data data-space is determined by dividing a relative base address of the data data-element by a bit length of the plurality of data data-elements within the data data-space.

38. The computer program of claim 27, wherein the original data-space contains a plurality of original data-elements of a first bit length and the index data-space contains a plurality of index data-elements of a second bit length.

39. The computer program of claim 38, wherein the first bit length and the second bit length are the same length.

40. The computer program of claim 38, wherein a location of the index data-element is determined from the location of its associated original data-element by dividing the location of the original data-element by the first bit length to produce a result and multiplying the result by the second bit length.

41. The computer program of claim 38, wherein the location of the original data-element is determined from a location of the index data-element by dividing a relative base address of the index data-element by the second bit length to produce a result and multiplying the result by the first bit length.