Managing cyclic constructs of XML schema in a rdbms

• US 8,554,789 B2
• Filed: 10/07/2005
• Issued: 10/08/2013
• Est. Priority Date: 10/07/2005
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Agrawal, Abhyudaya, Murthy, Ravi, Agarwal, Nipun, Chandrasekar, Sivasankaran, Sedlar, Eric
• Primary Examiner(s): Btit, Jacob F
• Assistant Examiner(s): TRAN, BAO G
• Application Number:
  US11/246,001
• Publication Number:
  US 20070083529A1
• Time in Patent Office: 2,923 Days
• Field of Search: 707/100, 707/3, 707/4, 707/102, 707/778, 707/829, 715/239
• US Class Current: 707/778
• CPC Class Codes: G06F 16/86 Mapping to a database
• CPC Class Codes: G06F 40/143 Markup, e.g. Standard Generalized Markup Language [SGML] or Document Type Definition [DTD]

Abstract

A database system automatically detects a cyclic construct in a XML schema, determines a database representation for the cyclic construct, and maps the XML schema and elements involved in the cyclic construct to the database representation.

Claims

1. A method, comprising

a database server registering a XML schema, wherein registering the XML schema includes:

traversing a declaration of a first element that comprises a second element;

while traversing said declaration of said first element;

tracking on a stack a declaration of an element or a type encountered during said traversing;

encountering said second element; and

determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of said first element by at least determining that said first element is on the stack; and

in response to determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element, performing;

determining that said XML schema defines a cyclic construct;

determining a database representation capable of storing instances of said XML schema that contain said cyclic construct; and

generating a mapping between constructs of said XML schema and said database representation.

2. The method of claim 1, wherein said registering a XML schema includes adding, within said XML schema, annotations that describe one or more properties of said database representation.

3. The method of claim 1, wherein:

determining that said XML schema defines a cyclic construct includes detecting that an ascendant element and a descendant element that descends from the ascendant element are involved in said cyclic construct;

the database representation includes an out-of-line table for storing said ascendant element; and

generating a mapping includes generating a mapping that maps said ascendant element to said out-of-line table.

4. The method of claim 3, wherein registering a XML schema includes adding within said XML schema an annotation that describes said out-of-line table.

5. The method of claim 3, wherein:

said descendant element and said ascendant element are mapped to an object type;

said out-of-line table is defined by said database server to store objects of said object type; and

said object type defines a reference for referring to an object within said out-of-line table.

6. The method of claim 1, wherein the second element is an ascendant of the first element.

7. The method of claim 1, wherein the first element and the second element are of a same type.

8. The method of claim 1, wherein determining that said XML schema defines a cyclic construct includes:

generating a dependency graph based on a declaration of one or more elements or types; and

detecting that said dependency graph includes a cycle.

9. A method, comprising

a database server registering a XML schema, wherein registering the XML schema includes:

traversing a declaration of a type of a first element that comprises a second element;

while traversing said declaration of said type of said first element;

tracking on a stack a declaration of an element or a type encountered during said traversing;

encountering said second element; and

determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element by at least determining that said certain type of said first element is on the stack; and

in response to determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element, performing;

determining that said XML schema defines a cyclic construct;

determining a database representation capable of storing instances of said XML schema that contain said cyclic construct; and

generating a mapping between constructs of said XML schema and said database representation.

10. A volatile or non-volatile computer-readable medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform

a database server registering a XML schema, wherein registering the XML schema includes:

traversing a declaration of a first element that comprises a second element;

while traversing said declaration of said first element;

tracking on a stack a declaration of an element or a type encountered during said traversing;

encountering said second element; and

determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of said first element by at least determining that said first element is on the stack; and

in response to determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element, performing;

determining that said XML schema defines a cyclic construct;

determining a database representation capable of storing instances of said XML schema that contain said cyclic construct; and

generating a mapping between constructs of said XML schema and said database representation.

11. The medium of claim 10, wherein said registering a XML schema includes adding, within said XML schema, annotations that describe one or more properties of said database representation.

12. The medium of claim 10, wherein:

determining that said XML schema defines a cyclic construct includes detecting that an ascendant element and a descendant element that descends from the ascendant element are involved in said cyclic construct;

the database representation includes an out-of-line table for storing said ascendant element; and

generating a mapping includes generating a mapping that maps said ascendant element to said out-of-line table.

13. The medium of claim 12, wherein registering a XML schema includes adding within said XML schema an annotation that describes said out-of-line table.

14. The medium of claim 12, wherein:

said descendant element and said ascendant element are mapped to an object type;

said out-of-line table is defined by said database server to store objects of said object type; and

said object type defines a reference for referring to an object within said out-of-line table.

15. The medium of claim 10, wherein the second element is an ascendant of the first element.

16. The medium of claim 10, wherein the first element and the second element are of a same type.

17. The medium of claim 10, wherein determining that said XML schema defines a cyclic construct includes:

generating a dependency graph based on a declaration of one or more elements or types; and

detecting that said dependency graph includes a cycle.

18. A volatile or non-volatile computer-readable medium storing one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform

a database server registering a XML schema, wherein registering the XML schema includes:

traversing a declaration of a type of a first element that comprises a second element;

while traversing said declaration of said type of said first element;

tracking on a stack a declaration of an element or a type encountered during said traversing;

encountering said second element; and

determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element by at least determining that said certain type of said first element is on the stack; and

in response to determining that said second element belongs to a type within a hierarchy of inheritance of a certain type of the first element, performing;

determining that said XML schema defines a cyclic construct;

determining a database representation capable of storing instances of said XML schema that contain said cyclic construct; and

generating a mapping between constructs of said XML schema and said database representation.