Database System Providing Methodology for Execution of Functions in XML Queries

• US 20060100989A1
• Filed: 10/21/2004
• Published: 05/11/2006
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Sybase Incorporated (SAP SE)
• Original Assignee: Sybase Incorporated (SAP SE)
• Inventors: Singh, Anupam, Sampath, Srikanth, Chinchwadkar, Gajanan S., Shaw, Phil
• Granted Patent: US 8,290,977 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/835 Query processing

Abstract

A database system providing methodology for execution of functions in queries requesting data from markup language documents is described. In one embodiment, for example, a method is described for executing a function in a query requesting data from a markup language document stored in a database, the markup language document organized hierarchically into nodes, the method comprises steps of: receiving the query requesting data from the markup language document, the query including a function to be executed during execution of the query; determining nodes of the markup language document satisfying the query; deriving values of the nodes of the markup language document; and executing the function with the derived values and the nodes of the markup language document.

Claims

1. A method for executing a function in a query requesting data from a markup language document stored in a database, the markup language document organized hierarchically into nodes, the method comprising:

receiving the query requesting data from the markup language document, the query including a function to be executed during execution of the query;

determining nodes of the markup language document satisfying the query;

deriving values of said nodes of the markup language document; and

executing the function with said derived values and said nodes of the markup language document.

2. The method of claim 1, wherein the markup language comprises Extensible Markup Language (XML).

3. The method of claim 1, wherein the query includes a path-based expression.

4. The method of claim 3, wherein said path-based expression comprises an XPath expression.

5. The method of claim 3, wherein said determining step includes determining nodes of the markup language document based, at least in part, on paths in the path-based expression.

6. The method of claim 3, wherein said path-based expression is included in a Structured Query Language (SQL) query.

7. The method of claim 1, wherein said determining step includes generating a plan for obtaining data requested by the query.

8. The method of claim 7, wherein the plan includes operators which are connected hierarchically such that results of a lower-level operator are input to a higher-level operator.

9. The method of claim 8, wherein the plan includes an operator representing the function.

10. The method of claim 9, wherein the plan includes an operator for deriving a value associated with a node of the markup language document.

11. The method of claim 10, wherein said determining step includes placing an operator for deriving a value below the operator representing the function in the plan so as to input derived values into the function.

12. The method of claim 10, wherein said deriving step includes deriving values of said nodes using said operator for deriving a value.

13. The method of claim 1, wherein said derived values comprise transient values generated during execution of the query.

14. The method of claim 1, further comprising:

associating said derived values with nodes of the markup language document.

15. The method of claim 14, wherein said associating step includes associating a derived value with one or more nodes of the markup language document.

16. The method of claim 14, wherein said associating step includes aggregating derived values of a plurality of nodes satisfying a portion of the query.

17. The method of claim 16, wherein said aggregating step includes concatenating string values of said plurality of nodes.

18. The method of claim 16, wherein said aggregating step includes synchronizing aggregated derived values with nodes of the markup language document.

19. The method of claim 18, wherein said aggregating step includes using a state transition mechanism for synchronization of aggregation boundaries.

20. The method of claim 19, wherein said state transition mechanism synchronizes aggregated derived values and user-supplied literals.

21. The method of claim 19, wherein said state transition mechanism synchronizes nodes without associated values.

22. The method of claim 16, wherein said associating step includes marshalling arguments from aggregated derived values at aggregation boundaries for input to the function.

23. The method of claim 22, wherein said executing step includes invoking the function with arguments generated from said aggregated derived values.

24. The method of claim 14, wherein said associating step includes associating user supplied literal values, derived values, and nodes of the markup language document.

25. The method of claim 14, wherein said associating step includes associating values with persistent nodes of the markup language document based on unique identifiers assigned to nodes of the markup language document.

26. The method of claim 1, further comprising:

returning results of execution of the function.

27. A computer-readable medium having processor-executable instructions for performing the method of claim 1.

28. A downloadable set of processor-executable instructions for performing the method of claim 1.

29. A system for executing a function included in a query requesting data from a markup language document stored in a database, the markup language document organized hierarchically into nodes, the system comprising:

a compiler module for generating a plan for identifying nodes of the markup language document satisfying the query; and

an execution module for executing the plan to identify nodes of the markup language document satisfying the query, obtaining values corresponding to identified nodes of the markup language document, associating said values with the identified nodes, and executing the function included in the query with said values and identified nodes.

30. The system of claim 29, wherein the markup language comprises Extensible Markup Language (XML).

31. The system of claim 29, wherein the query includes an XPath query expression.

32. The system of claim 31, wherein said XPath query expression is included in a Structured Query Language (SQL) query.

33. The system of claim 29, wherein said value module aggregates values when multiple nodes satisfy a query expression.

34. The system of claim 33, wherein said execution module marshals said values at aggregation boundaries.

35. The system of claim 34, wherein said execution module determines aggregation boundaries based on outer path context.

36. The system of claim 34, wherein said execution module includes a state transition mechanism for synchronizing aggregation boundaries.

37. The system of claim 36, wherein said state transition mechanism synchronizes aggregation boundaries of a node without an associated value.

38. The system of claim 36, wherein said state transition mechanism synchronizes aggregation boundaries of nodes from different subtrees in the markup language document.

39. The system of claim 29, wherein the compiler module parses the query to create an in-memory representation of the query in tree form.

40. The system of claim 29, wherein said compiler module generates an execution plan for execution of the query.

41. The system of claim 40, wherein the execution plan includes operators which are connected hierarchically such that results of a lower-level operator are input to a higher-level operator.

42. The system of claim 41, wherein the execution plan includes an operator for obtaining a value associated with a node of the markup language document.

43. The system of claim 42, wherein the execution plan includes an operator for executing a function included in the query.

44. The system of claim 29, wherein each node of the markup language document stored in the database is identified by a unique identifier.

45. The system of claim 29, wherein a node of the markup language document corresponds to an element of the markup language document stored in the database.

46. The system of claim 29, wherein said execution module associates a value with one or more nodes of the markup language document.

47. The system of claim 29, wherein said execution module performs a string function.

48. The system of claim 47, wherein said string function comprises a selected one or more of a tolower( ) function, a toupper( ) function, a normalize-space( ) function, and a concat( ) function.

49. The system of claim 29, wherein said execution module aggregates values of a plurality of identified nodes.

50. The system of claim 49, wherein said execution module synchronizes aggregate values with nodes of the markup language document.

51. The system of claim 50, wherein said execution module includes a state transition mechanism for synchronization of aggregation boundaries.

52. The system of claim 29, further comprising:

a module for transforming a markup language document comprising a plurality of elements for storage in a database.

53. The system of claim 52, wherein the module for transforming assigns a unique identifier to each element of the markup language document.

54. The system of claim 53, wherein the unique identifier is based on order each element appears in the markup language document.

55. The system of claim 29, wherein the execution module returns results in order in which elements appear in the markup language document.

56. The system of claim 29, wherein said compiler module generates a plan for identifying nodes of the markup language document satisfying the query based on paths in the query.

57. The system of claim 56, wherein said execution module performs aggregation on said paths.

58. The system of claim 29, wherein said execution module associates said values with user supplied literal values for executing the function.

59. The system of claim 29, wherein the execution module returns results of execution of the function.

60. In a database system, a method for executing a function in a query requesting data from an Extensible Markup Language (XML) document, the method comprising:

receiving the query requesting data from an XML document, the query including a function to be executed on data from an XML document which includes a plurality of hierarchically arranged elements;

determining elements of the XML document satisfying the query;

obtaining values of said elements of the XML document;

associating said values with elements of the XML document; and

executing the function with said values and associated elements.

61. The method of claim 60, wherein the query includes an XPath query expression.

62. The method of claim 61, wherein said XPath query expression is included in a Structured Query Language (SQL) query.

63. The method of claim 60, wherein said obtaining step includes aggregating values of a plurality of elements satisfying a portion of the query.

64. The method of claim 63, wherein said associating step includes marshalling arguments to the function at aggregation boundaries.

65. The method of claim 64, wherein said aggregation boundaries are determined based on outer path context.

66. The method of claim 64, wherein said associating step includes using a state transition mechanism for synchronizing aggregation boundaries.

67. The method of claim 66, wherein said state transition mechanism synchronizes aggregation boundaries of an element without an associated value.

68. The method of claim 66, wherein said state transition mechanism synchronizes aggregation boundaries for elements from different subtrees in the XML document.

69. The method of claim 60, wherein said determining step includes parsing the query to create an in-memory representation of the query in tree form.

70. The method of claim 60, wherein said determining step includes generating an execution plan for execution of the query.

71. The method of claim 70, wherein said execution plan includes operators connected hierarchically such that results of a lower-level operator are input to a higher-level operator.

72. The method of claim 70, wherein said execution plan includes an operator for executing the function.

73. The method of claim 72, wherein said operator for executing the function performs a string function.

74. The method of claim 73, wherein said string function comprises one or more of a tolower( ) function, a toupper( ) function, a normalize-space( ) function, and a concat( ) function.

75. The method of claim 70, wherein said execution plan includes an operator for obtaining a value for an element of the XML document.

76. The method of claim 75, wherein said obtaining step includes obtaining a value of an element of the XML document using said operator for obtaining a value.

77. The method of claim 60, wherein said executing step includes invoking the function operator with said values and user supplied literal values.

78. The method of claim 60, further comprising:

returning results of execution of the function.

79. A computer-readable medium having processor-executable instructions for performing the method of claim 60.

80. A downloadable set of processor-executable instructions for performing the method of claim 60.

81. In a database system, a method for executing a function included in a query requesting data from an XML document organized hierarchically into nodes, the method comprising:

generating an execution plan for obtaining data requested by the query from an XML document, the execution plan including an operator for performing the function included in the query;

inserting an operator for obtaining values corresponding to nodes of the XML document into the execution plan;

identifying nodes of the XML document satisfying the query based on the execution plan;

deriving values from identified nodes of the XML document using the operator for obtaining values; and

invoking the operator for performing the function with the values derived from the identified nodes of the XML document.

82. The method of claim 81, wherein said deriving step includes aggregating derived values of a plurality of identified nodes.

83. The method of claim 82, wherein said aggregating step includes synchronizing aggregation boundaries so as to associate values with particular nodes of the XML document.

84. The method of claim 83, wherein said aggregating step includes using a state transition mechanism for synchronization of aggregation boundaries.

85. The method of claim 84, wherein said state transition mechanism synchronizes aggregated derived values and user-supplied literals.

86. The method of claim 81, wherein said inserting step includes inserting a physical query plan operator for associating derived values with nodes of the XML document.

87. The method of claim 81, wherein said invoking step includes invoking the operator for performing the function with user supplied literal values and the values derived from identified nodes of the XML document.

88. The method of claim 81, wherein said deriving step includes deriving values associated with persistent nodes of the XML document based on unique identifiers assigned to nodes of the XML document.

89. A computer-readable medium having processor-executable instructions for performing the method of claim 81.

90. A downloadable set of processor-executable instructions for performing the method of claim 81.