Method, system, and program for predicate processing by iterator functions

• US 20050071326A1
• Filed: 09/29/2003
• Published: 03/31/2005
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Brown, Kevin, Murthy, Raghupathi Keshava
• Granted Patent: US 7,685,103 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/35 Clustering; Classification
• CPC Class Codes: G06F 16/353 into predefined classes
• CPC Class Codes: G06F 16/986 Document structures and storage, e.g. HTML extensions
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching

Abstract

Disclosed is a technique for processing predicates in an iterator function. When an iterator function included in a statement is invoked, one or more predicates included in the statement are obtained. The one or more predicates are applied to a row of data. If applying the one or more predicates results in a match, the row of data is returned. If applying the one or more predicates does not result in a match, a search is performed for another row of data for which application of the one or more predicates results in a match. Also disclosed is a technique for processing predicates in which a statement including an iterator function and one or more predicates is received. A qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates is created. Then, the iterator function is invoked one or more times, until receiving a done indicator from the iterator function.

Claims

1. A method for processing predicates in an iterator function, comprising:

when an iterator function included in a statement is invoked,

obtaining one or more predicates included in the statement;

applying the one or more predicates to a row of data;

if applying the one or more predicates results in a match, returning the row of data; and

if applying the one or more predicates does not result in a match, searching for another row of data for which application of the one or more predicates results in a match.

2. The method of claim 1, wherein obtaining the one or more predicates comprises:

obtaining a qualification descriptor that describes the one or more predicates and one or more functions.

3. The method of claim 2, wherein each function is used to process one of the predicates.

4. The method of claim 1, wherein each of the one or more predicates comprises a simple predicate.

5. The method of claim 1, wherein the iterator function is invoked by a data store engine and further comprising:

returning the row of data to the data store engine.

6. A method for processing predicates, comprising:

receiving a statement including an iterator function and one or more predicates;

creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

invoking the iterator function one or more times, until receiving a done indicator from the iterator function.

7. The method of claim 6, wherein the qualification descriptor provides a handle to each of the one or more functions.

8. The method of claim 6, further comprising:

when the iterator function is invoked, receiving an indication from the iterator function indicating whether the one or more predicates were applied by the iterator function.

9. The method of claim 6, further comprising:

when the iterator function is invoked, receiving a row of data from the iterator function that matches the qualification of the one or more predicates.

10. The method of claim 9, further comprising:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates refer to a column of data that is not in a result set generated by the iterator function.

11. The method of claim 9, further comprising:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates performs a join between two tables.

12. A method for processing predicates, comprising:

under control of a data store engine,

receiving a statement including an iterator function and one or more predicates;

creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

invoking the iterator function; and

under control of an iterator function processor,

retrieving the qualification descriptor;

obtaining a row of data that matches the qualification in the qualification descriptor; and

returning the row of data to the data store engine.

13. The method of claim 12, wherein the qualification descriptor describes one or more simple predicates to be applied by the iterator function processor.

14. An article of manufacture including a program for processing predicates in an iterator function, wherein the program causes operations to be performed, the operations comprising:

when an iterator function included in a statement is invoked,

obtaining one or more predicates included in the statement;

applying the one or more predicates to a row of data;

if applying the one or more predicates results in a match, returning the row of data; and

if applying the one or more predicates does not result in a match, searching for another row of data for which application of the one or more predicates results in a match.

15. The article of manufacture of claim 14, wherein operations for obtaining the one or more predicates further comprise:

obtaining a qualification descriptor that describes the one or more predicates and one or more functions.

16. The article of manufacture of claim 15, wherein each function is used to process one of the predicates.

17. The article of manufacture of claim 14, wherein each of the one or more predicates comprises a simple predicate.

18. The article of manufacture of claim 14, wherein the iterator function is invoked by a data store engine and wherein the operations further comprise:

returning the row of data to the data store engine.

19. An article of manufacture including a program for processing predicates, wherein the program causes operations to be performed, the operations comprising:

receiving a statement including an iterator function and one or more predicates;

creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

invoking the iterator function one or more times, until receiving a done indicator from the iterator function.

20. The article of manufacture of claim 19, wherein the qualification descriptor provides a handle to each of the one or more functions.

21. The article of manufacture of claim 19, wherein the operations further comprise:

when the iterator function is invoked, receiving an indication from the iterator function indicating whether the one or more predicates were applied by the iterator function.

22. The article of manufacture of claim 19, wherein the operations further comprise:

when the iterator function is invoked, receiving a row of data from the iterator function that matches the qualification of the one or more predicates.

23. The article of manufacture of claim 22, wherein the operations further comprise:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates refer to a column of data that is not in a result set generated by the iterator function.

24. The article of manufacture of claim 22, wherein the operations further comprise:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates performs a join between two tables.

25. An article of manufacture including a program for processing predicates, wherein the program causes operations to be performed, the operations comprising:

under control of a data store engine,

receiving a statement including an iterator function and one or more predicates;

creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

invoking the iterator function; and

under control of an iterator function processor,

retrieving the qualification descriptor;

obtaining a row of data that matches the qualification in the qualification descriptor; and

returning the row of data to the data store engine.

26. The article of manufacture of claim 25, wherein the qualification descriptor describes one or more simple predicates to be applied by the iterator function processor.

27. A computer system having at least one program for processing predicates in an iterator function, comprising:

when an iterator function included in a statement is invoked,

obtaining one or more predicates included in the statement;

applying the one or more predicates to a row of data;

if applying the one or more predicates results in a match, returning the row of data; and

if applying the one or more predicates does not result in a match, searching for another row of data for which application of the one or more predicates results in a match.

28. The computer system of claim 27, wherein obtaining the one or more predicates comprises:

obtaining a qualification descriptor that describes the one or more predicates and one or more functions.

29. The computer system of claim 28, wherein each function is used to process one of the predicates.

30. The computer system of claim 27, wherein each of the one or more predicates comprises a simple predicate.

31. The computer system of claim 27, wherein the iterator function is invoked by a data store engine and further comprising:

returning the row of data to the data store engine.

32. A computer system having at least one program for processing predicates, comprising:

receiving a statement including an iterator function and one or more predicates;

creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

invoking the iterator function one or more times, until receiving a done indicator from the iterator function.

33. The computer system of claim 32, wherein the qualification descriptor provides a handle to each of the one or more functions.

34. The computer system of claim 32, further comprising:

when the iterator function is invoked, receiving an indication from the iterator function indicating whether the one or more predicates were applied by the iterator function.

35. The computer system of claim 32, further comprising:

when the iterator function is invoked, receiving a row of data from the iterator function that matches the qualification of the one or more predicates.

36. The computer system of claim 35, further comprising:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates refer to a column of data that is not in a result set generated by the iterator function.

37. The computer system of claim 35, further comprising:

applying one or more additional predicates to the received row of data, wherein the one or more additional predicates performs a join between two tables.

38. A computer system for processing predicates, comprising:

under control of a data store engine,

means for receiving a statement including an iterator function and one or more predicates;

means for creating a qualification descriptor that describes the one or more predicates and one or more functions that are to be used to evaluate the one or more predicates; and

means for invoking the iterator function; and

under control of an iterator function processor,

means for retrieving the qualification descriptor;

means for obtaining a row of data that matches the qualification in the qualification descriptor; and

means for returning the row of data to the data store engine.

39. The computer system of claim 38, wherein the qualification descriptor describes one or more simple predicates to be applied by the iterator function processor.