Method of capturing data changes utilizing data-space tracking

• US 7,502,800 B2
• Filed: 12/07/2005
• Issued: 03/10/2009
• Est. Priority Date: 07/19/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Watts, Vern L., Beier, Harley A.
• Primary Examiner(s): Breene; John
• Assistant Examiner(s): To; Baoquoc N
• Application Number:
  US11/295,476
• Publication Number:
  US 20060074951A1
• Time in Patent Office: 1,189 Days
• Field of Search: 707/200, 707/202, 707/3, 707/100, 707/103, 707/104.1, 707/203, 707/204, 707/103.R, 707/103.Z
• 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

A method of reorganizing a database while concurrently providing access to the database for updates. In an exemplary embodiment of the method, 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 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,

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.

2. The method of claim 1, 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.

3. The method of claim 2, 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.

4. The method of claim 2, 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.

5. The method of claim 1, 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.

6. The method of claim 1, wherein the index data-space and data data-space are stored in non-persistent storage.

7. The method of claim 1, wherein the index data-space and data data-space are stored in persistent storage.

8. The method of claim 1, 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.

9. The method of claim 1, 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.

10. The method of claim 1, 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.

11. The method of claim 1, 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.

12. The method of claim 11, wherein the first bit length and the second bit length are the same length.

13. The method of claim 11, 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.

14. The method of claim 11, 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.