Techniques for changing XML content in a relational database

• US 6,836,778 B2
• Filed: 05/01/2003
• Issued: 12/28/2004
• Est. Priority Date: 05/01/2003
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Manikutty, Anand, Sedlar, Eric, Khaladkar, Bhushan, Murthy, Ravi, Krishnaprasad, Muralidhar, Warner, James, Jalali, Neema, Nimani, Visar
• Primary Examiner(s): Mizrahi, Diane D.
• Application Number:
  US10/428,445
• Publication Number:
  US 20040220912A1
• Time in Patent Office: 607 Days
• Field of Search: 707/102, 707/1, 707/3, 707/100, 707/513, 709/315
• US Class Current: 1/1
• CPC Class Codes: G06F 16/30 of unstructured textual data document management systems G06F16/93
• CPC Class Codes: G06F 16/83 Querying
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

Techniques are provided for changing data for an XML construct in an SQL/XML compliant database management system (DBMS). The DBMS allows instances of XML type to represent XML constructs, such as XML documents, XML elements, XML attributes, and fragments of XML documents. An SQL statement is received that includes an XML operator that operates on a particular component in an instance of XML type. During execution of the SQL statement, the XML operator is evaluated by modifying content for the component without modifying the entire instance. For example, an XML delete operator deletes the particular component from the instance. Other XML operators include an insert operator, an insert-before operator, an append-child operator, and an update operator. During execution, these operators may be rewritten to operate on existing SQL constructs, or evaluated by updating only some of the existing SQL constructs, or both.

Claims

1. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving a SQL statement that includes an operator that operates on a component that is less than all of an instance of XML type; and

during execution of the SQL statement, evaluating the operator by modifying content for the component without modifying all of the instance of XML type.

2. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language(SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving a SQL statement that includes a delete operator that operates on a first component of an instance of XML type; and

during execution of the SQL statement, evaluating the delete operator by deleting the first component from the instance of XML type.

3. The method as recited in claim 2, further comprising, during execution of the SQL statement, performing the step of changing a particular SQL construct that stores data representing the component to exclude data representing the component.

4. The method as recited in claim 2, said step of evaluating the delete operator further comprising the steps of:

representing the first instance of XML type in memory as a plurality of data structures, wherein each data structure represents a particular node in an XML tree hierarchy that corresponds to the first instance of XML type and each data structure includes a set of pointers that point to any child nodes of the particular node;

traversing the XML tree hierarchy to reach a first data structure representing a first node that corresponds to the component; and

deleting the first data structure.

5. The method as recited in claim 4, wherein:

said step of representing the first instance of XML type in memory further comprises including in each data structure, a bit vector equal in length to a number of the child nodes of the particular node represented by the data structure; and

said step of evaluating the delete operator further comprising the step of changing a bit to indicate a modified child at a bit corresponding to the first node in a first bit vector in a second data structure that represents a parent node of the first node.

6. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving an SQL statement that includes an insert operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct,

data that indicates a name an element for the first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the insert operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that is a child XML element of the first XML construct and has an XML element name based on the data that indicates the name.

7. The method as recited in claim 6, said step of evaluating the insert operator further comprising the step of generating a particular SQL construct that stores data that represents the second XML construct.

8. The method as recited in claim 6, said step of evaluating the insert operator further comprising the steps of:

determining whether a third XML element exists in the instance of XML type, which third XML element is a child XML element of the first XML construct and has the same XML element name as the second XML element; and

if the third XML element exists, then said step of generating the second component representing the second XML construct further comprises inserting the second XML construct after the third XML element in XML document order.

9. The method as recited in claim 6, said step of evaluating the insert operator further comprising the steps of:

representing the instance of XML type in memory as a plurality of data structures, wherein each data structure represents a particular node in an XML tree hierarchy that corresponds to the instance of XML type and each data structure includes a set of pointers that point to any child nodes of the particular node;

traversing the XML tree hierarchy to reach a first data structure representing a first node that corresponds to the first XML construct; and

generating a second data structure that corresponds to the second XML construct.

10. The method as recited in claim 9, wherein:

said step of representing the instance of XML type in memory further comprises including in each data structure, a bit vector equal in length to a number of the child nodes of the particular node represented by the data structure; and

said step of evaluating the insert operator further comprising the step of adding a bit that indicates a modified child to a first bit vector in the first data structure.

11. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving an SQL statement that includes an insert-before operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the insert-before operator by generating, based on the expression for the particular value, a second component representing a second XML construct inserted before the first XML construct in the instance of XML type in XML document order.

12. The method as recited in claim 11, said step of evaluating the insert-before operator comprising the steps of generating a particular SQL construct that stores data that represents the second XML construct.

13. The method as recited in claim 11, said step of evaluating the insert-before operator further comprising the steps of:

representing the instance of XML type in memory as a plurality of data structures, wherein each data structure represents a particular node in an XML tree hierarchy that corresponds to the instance of XML type and each data structure includes a set of pointers that point to any child nodes of the particular node;

traversing the XML tree hierarchy to reach a first data structure representing a first node that corresponds to the first XML construct; and

generating a second data structure that corresponds to the second XML construct.

14. The method as recited in claim 13, wherein:

said step of representing the XML construct in memory further comprises including in each data structure, a bit vector equal in length to a number of the child nodes of the particular node represented by the data structure; and

said step of evaluating the insert-before operator further comprising the step of adding a bit that indicates a modified child to a first bit vector in a third data structure that represents a parent node of the first node.

15. The method as recited in claim 11, wherein:

said step of evaluating the insert-before operator further comprises the step of determining whether the first XML construct is an XML element; and

said step of generating the second XML construct further comprises generating the second XML construct as a child XML element of a parent element of the first XML construct if it is determined that the first XML construct is an XML element.

16. The method as recited in claim 15, said step of generating the second XML construct further comprising the step of generating the second XML construct as a XML attribute of the parent element of the first XML construct, if it is determined that the first XML construct is an XML attribute.

17. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving an SQL statement that includes an append-child operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the append-child operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that is a child of the first XML construct in the instance of XML type.

18. The method as recited in claim 17, said step of evaluating the append-child operator further comprising the steps of generating a particular SQL construct that stores data that represents the second XML construct.

19. The method as recited in claim 17, said step of evaluating the append-child operator further comprising the steps of:

representing the instance of XML type in memory as a plurality of data structures, wherein each data structure represents a particular node in an XML tree hierarchy that corresponds to the instance of XML type and each data structure includes a set of pointers that point to any child nodes of the particular node;

traversing the XML tree hierarchy to reach a first data structure representing a first node that corresponds to the first XML construct;

generating a second data structure that corresponds to the second XML construct.

20. The method as recited in claim 19, wherein:

said step of representing the instance of XML type in memory further comprises including in each data structure, a bit vector equal in length to a number of the child nodes of the particular node represented by the data structure; and

said step of evaluating the append-child operator further comprising the step of adding a bit that indicates a modified child to a first bit vector in the first data structure.

21. The method as recited in claim 17, wherein:

said step of evaluating the append-child operator further comprises the step of determining whether the first XML construct is an XML element; and

said step of generating the second component is performed only if it is determined that the first XML construct is an XML element.

22. A method for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving a SQL statement that includes an update operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the update operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that replaces the first XML construct in the instance of XML type.

23. The method as recited in claim 22, said step of evaluating the update operator further comprising the steps of generating a first SQL construct that stores data that represents the instance XML of XML type.

24. The method as recited in claim 22, wherein:

said step of evaluating the update operator further comprising the steps of;

modifying an in-memory representation of the instance of XML type;

determining whether a portion of the in-memory representation that is modified during said step of modifying the in-memory representation is less than all of the in-memory portion;

if it is determined that the portion is less than all of the in-memory representation, then determining whether an SQL construct stores data for the portion; and

modifying the SQL construct.

25. The method as recited in claim 22, wherein:

the method further comprises the step of compiling the SQL statement, including;

determining a particular set of one or more SQL constructs that are affected by the update operator operating on the first component of the instance of XML type; and

rewriting the SQL statement on the first component as a set of one or more SQL operations on the particular set of one or more SQL constructs; and

said step of evaluating the update operator comprises evaluating the set of one or more SQL operations on the particular set of one or more SQL constructs.

26. The method as recited in claim 25, wherein the particular set of one or more SQL constructs includes fewer SQL constructs than a complete set of SQL constructs that store data for all descendent XML constructs of the instance of XML type.

27. A method for executing database update commands on extensible markup language (XML constructs in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving a database modification statement to modify a first component in an instance of XML type, wherein the first component represents a first XML construct; and

during execution of the database modification statement, evaluating the database modification statement, including

determining, of the instance of XML type, a first portion that is affected by executing the database modification statement, wherein the first portion is less than all of the instance of XML type; and

mapping the first portion to a first set of at least one SQL construct; and

updating the first set of at least one SQL construct without updating a second set of at least one SQL construct that represents a second portion of the instance of XML type, wherein the second portion is not affected by executing the database modification statement.

28. The method of claim 27, wherein:

the method further includes the step of representing the instance of XML type in memory as a plurality of data structures;

each data structure represents a particular node in an XML tree hierarchy that corresponds to the instance of XML type; and

said step of determining the first portion comprises determining which data structure is associated with contents which have changed during said step of evaluating the database modification statement.

29. The method of claim 28, wherein:

each data structure includes a set of zero or more bits that indicates whether the contents associated with the data structure have changed during said step of evaluating the database modification statement; and

said step of determining the particular portion further comprises determining for each data structure of the plurality of data structures whether the set of zero or more bits indicates that contents associated with the data structure have changed.

30. The method of claim 29, wherein the set of zero or more bits at each data structure includes a bit for each child node of a node represented by the data structure.

31. A method for executing database update commands on extensible markup language (XML) constructs in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, comprising the steps of:

receiving a database modification statement to modify a first component in an instance of XML type, wherein the first component represents a first XML construct;

compiling the database modification statement, including;

determining a particular set of one or more SQL constructs that are affected by the database modification statement; and

rewriting the database modification statement as a set of one or more SQL operations on the particular set of one or more SQL constructs; and

evaluating the database modification statement by evaluating the set of one or more SQL operations on the particular set of one or more SQL constructs.

32. The method as recited in claim 31, wherein the particular set of one or more SQL constructs includes fewer SQL constructs than a complete set of SQL constructs that represent all descendent XML constructs of the instance of XML type.

33. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management sys tem (DBMS) that uses instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving a SQL statement that includes an operator that operates on a component that is less than all of an instance of XML type; and

during execution of the SQL statement, evaluating the operator by modifying content for the component without modifying all of the instance of XML type.

34. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving a SQL statement that includes a delete operator that operates on a first component of an instance of XML type; and

during execution of the SQL statement, evaluating the delete operator by deleting the first component from the instance of XML type.

35. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving an SQL statement that includes an insert operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct,

data that indicates a name of an element for the first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the insert operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that is a child XML element of the first XML construct and has an XML element name based on the data that indicates the name.

36. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving an SQL statement that includes an insert-before operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the insert-before operator by generating, based on the expression for the particular value, a second component that represents a second XML construct inserted before the first XML construct in thee instance of XML type in XML document order.

37. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving an SQL statement that includes an append-child operator that operates on a first components in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular vale for XML content; and

during execution of the SQL statement, evaluating the append-child operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that is a child of the first XML construct in the instance of XML type.

38. A computer-readable medium carrying one or more sequences of instructions for changing data for an eXtensible Markup-Language (XML) construct in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving a SQL statement that includes an update operator that operates on a first component in an instance of XML type, wherein the first component represents a first XML construct, and

an expression for a particular value for XML content; and

during execution of the SQL statement, evaluating the update operator by generating, based on the expression for the particular value, a second component that represents a second XML construct that replaces the first XML construct in the instance of XML type.

39. A computer-readable medium carrying one or more sequences of instructions for executing database update commands on extensible markup language (XML) constructs in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving a database modification statement to modify a first component in an instance of XML type, wherein the first component represents a first XML construct; and

during execution of the database modification statement, evaluating the database modification statement, including

determining, of the instance of XML type, a first portion that is affected by executing the database modification statement, wherein the first portion is less than all of the instance of XML type; and

mapping the first portion to a first set of at least one SQL construct; and

updating the first set of at least one SQL construct without updating a second set of at least one SQL construct that represents a second portion of the instance of XML type, wherein the second portion is not affected by executing the database modification statement.

40. A computer-readable medium carrying one or more sequences of instructions for executing database update commands on extensible markup language (XML) constructs in a Structured Query Language (SQL) compliant database management system (DBMS) that allows instances of XML type to represent XML constructs, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

receiving a database modification statement to modify a first component in an instance of XML type, wherein the first component represents a first XML construct;

compiling the database modification statement, including;

determining a particular set of one or more SQL constructs that are affected by the database modification statement; and

rewriting the database modification statement as a set of one or more SQL operations on the particular set of one or more SQL constructs; and

evaluating the database modification statement by evaluating the set of one or more SQL operations on the particular set of one or more SQL constructs.