Execution of database queries including filtering

• US 6,879,977 B2
• Filed: 01/10/2001
• Issued: 04/12/2005
• Est. Priority Date: 04/28/2000
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: McKnight, Kathy A., Huffman, Paul C., Sharpe, David C., Zilio, Daniel C.
• Primary Examiner(s): Corrielus, Jean M.
• Assistant Examiner(s): Ly, Anh
• Application Number:
  US09/757,428
• Publication Number:
  US 20010037329A1
• Time in Patent Office: 1,553 Days
• Field of Search: 707 1- 10
• US Class Current: 1/1
• CPC Class Codes: G06F 16/24554 Unary operations; Data partitioning operations
• CPC Class Codes: G06F 16/24557 Efficient disk access during query execution
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99935 Query augmenting and refining, e.g. inexact access
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A query processing system has a query processor and a data manager. The query processor calls the data manager to carry out data access for a query including a filtering operation. The data manager accesses the data in a set of data and before returning the data, initiates a callback to the query processor to determine if the located data meets the filtering criteria. Where the data does not satisfy the filtering criteria, the data manager seeks additional data in the set of data, without having to return the first located data to the query processor.

Claims

1. A method for processing a database query on a set of data resulting in an access plan, comprising the steps of:

(a) calling a data manager by a query manager to access a query-specified data in the set of data,

(b) performing a callback to the query manager by the data manager when the data manager locates the query-specified data,

(c) executing a filtering operation on the located query-specified data by the query manager and indicating to the data manager whether the query-specified data qualifies in response to the callback, and

(d) returning the query-specified data by the data manager if the response from the query manager to the callback indicates that the query-specified data qualifies.

2. The method of claim 1, in which the set of data is stored on pages.

3. The method of claim 2 comprising the step (e) of stabilizing the page by the data manager on which the query-specified data is located prior to access said data.

4. The method of claim 3 further comprising the step of:

(f) maintaining the stabilization of the page during callback to the query manager.

5. The method of claim 3 in which the database query comprises an SQL DISTINCT clause.

6. The method of claim 1 in which the database query comprises an SQL DISTINCT clause.

7. A query processing system comprising;

a data manager; and

a query manager for processing a database query on a set of data, resulting in an access plan, including a filtering operation, wherein the query manager comprising means for calling the data manager to access query-specified data in the set of data, the data manager comprising means for performing a callback to the query manager when data manager locates the query-specified data, the query manager comprising means for executing the filtering operation on the located query-specified data and indicating to the data manager, in response to the callback, whether the query-specified data qualifies, and the data manager comprising means for returning the query-specified data if the response from the query manager to the callback indicates that the query-specified data qualifies.

8. The query processing system of claim 7, in which the set of data is stored on pages and data manager further comprises means for stabilizing the page on which the query-specified data is located prior to access said data, and means for maintaining the stabilization of the page during callback to the query manager.

9. A computer readable medium containing program instructions for processing a database query on a set of data resulting in an access plan, the program instructions for:

(a) calling a data manager by a query manager to access a query-specified data in the set of data,

(b) performing a callback to the query manager by the data manager when the data manager locates the query-specified data,

(c) executing a filtering operation on the located query-specified data by the query manager and indicating to the data manager whether the query-specified data qualifies, in response to the callback, and

(d) returning the query-specified data by the data manager if the response from the query manager to the callback indicates that the query-specified data qualifies.

10. The computer readable medium of claim 9, in which the set of data is stored on pages.

11. The computer readable medium of claim 10 comprising program instructions for (e) stabilizing the page by the data manager on which the query-specified data is located prior to access said data.

12. The computer readable medium containing program instructions of claim 11 further comprising program instructions for:

(f) maintaining the stabilization of the page during callback to the query manager.

13. The computer readable medium containing program instructions of claim 11 in which the database query comprises an SQL DISTINCT clause.

14. The computer readable medium containing program instructions of claim 9 in which the database query comprises an SQL DISTINCT clause.