Method, apparatus, and program for capturing data changes utilizing data-space tracking

• US 8,200,665 B2
• Filed: 10/29/2008
• Issued: 06/12/2012
• Est. Priority Date: 07/19/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Beier, Harley A., Watts, Vern L.
• Primary Examiner(s): To, Baoquoc
• Application Number:
  US12/260,599
• Publication Number:
  US 20090055448A1
• Time in Patent Office: 1,322 Days
• Field of Search: None
• US Class Current: 707/726
• 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, apparatus, and program for reorganizing a database while concurrently providing access to the database for updates. In an exemplary embodiment of the invention, 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, each of the plurality of original data-elements including a change flag, 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;

setting the change flag of a first original data-element among the plurality of original data-elements that is changed after the contents of the first original data-element are copied to the shadow data-element to indicate that the contents of the first original data-element are changed after the contents of the first original data-element are copied to the shadow data-element;

determining that the contents of the first original data-element that are changed after the contents of the first original data-element are copied to the shadow data-element, based on the change flag; and

copying data from a location of the changed first original data-element to a location of a shadow data-element in the reorganized shadow data-space corresponding to the changed first original data-element, in response to the determining.

2. 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, each of the plurality of data data-elements including a change flag, 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 a first original data-element in the original data-space to a corresponding shadow data-element in the shadow data-space and to associate the first 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 the first original data-element after the reorganization module copies the contents of the first original data-element to the corresponding shadow data-element and to update the change flag of a data data-element associated with the first original data-element to indicate that a change has occurred in the first original data-element after the reorganization module copies the contents of the first original data-element to the corresponding shadow data-element; and

a pending change module configured to detect the change in the first original data-element based on the updated change flag of the data-data element associated with the first original data-element and apply the change in the first original data-element to the shadow data-element corresponding to the first original data-element, in response to detecting the change.

3. The apparatus of claim 2, wherein the log intercept module updates the data data-element to record information indicating that the first original data-element has been at least one of added, updated and deleted.

4. The apparatus of claim 2, 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.

5. The apparatus of claim 4, 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.

6. The apparatus of claim 4, 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.

7. The apparatus 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.

8. The apparatus of claim 7, wherein the first bit length and the second bit length are the same length.

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

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

11. 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, each of the plurality of data data-elements including a change flag, and an index data-space having a plurality of index data-elements, the method comprising:

program instructions for copying contents of a first original data-element within the original data-space to a shadow data-element within the shadow data-space and associating the first 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 the contents of the original data-element are copied to the shadow data-element by updating the change flag of the data data-element that is located using an index data-element after the contents of the first original data-element are copied to the shadow data-element to indicate that the contents of the first original data-element are changed after the contents of the first original data-element are copied to the shadow data-element;

program instructions for determining that the contents of the first original data-element are changed after the contents of the first original data-element are copied to the shadow data-element, based on the change flag; and

program instructions for copying data from a location of the changed first original data-element to a location of a shadow data-element in the reorganized shadow data-space corresponding to the changed first original data-element, in response to the determining.