Fast extraction of scalar values from binary encoded XML

• US 8,429,196 B2
• Filed: 06/06/2008
• Issued: 04/23/2013
• Est. Priority Date: 06/06/2008
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Chandrasekar, Sivasankaran, Zhang, Ning, Idicula, Sam, Agarwal, Nipun
• Primary Examiner(s): Alam, Hosain
• Assistant Examiner(s): Hosseini, Reza
• Application Number:
  US12/134,196
• Publication Number:
  US 20090307239A1
• Time in Patent Office: 1,782 Days
• Field of Search: 707/797, 707/798, 707802-807, 707999001-99901, 707/999.1, 707999101-999107, 7079992-999206, 715205-209, 715/234
• US Class Current: 707/797
• CPC Class Codes: G06F 16/83 Querying

Abstract

Techniques are provided for efficiently extracting scalar values from binary-encoded XML data. Node information is stored in association with binary-encoded XML data to indicate whether one or more nodes of an XML document are simple or complex. A node is simple if the node has no child elements and no attributes. The node information of a particular node is used to determine whether a particular node, identified in a query, is simple or complex. If the particular node is simple, then the scalar value of the particular node is identified without performing any operations other than possibly converting the scalar value to a non-binary-encoded format or converting the scalar value to a value of a different data type.

Claims

1. A method comprising:

receiving a query that requires one or more XML nodes that are binary-encoded;

in response to receiving the query, requesting binary-encoded XML data from one or more data sources, wherein the binary-encoded XML data is a compact binary representation of textual XML data;

determining that a particular node reflected in the binary-encoded XML data satisfies one or more criteria of the query;

after determining that the particular node satisfies one or more criteria of the query and before extracting content of the particular node, determining whether the particular node is simple or complex, wherein a node is simple if the node has no child elements and no associated attributes, wherein a node is complex if the node has at least one child element or at least one attribute;

if it is determined that the particular node is complex, then extracting, from the binary-encoded XML data, a scalar value of the particular node by performing a first set of one or more operations;

if it is determined that the particular node is simple, then extracting, from the binary-encoded XML data, a scalar value of the particular node without performing the first set of one or more operations;

wherein the method is performed by one or more computing devices.

2. The method of claim 1, wherein extracting the scalar value comprises converting the scalar value of the particular node into a non-binary-encoded format.

3. The method of claim 2, wherein converting the scalar value of the particular node into a non-binary-encoded format is performed after the scalar value is identified.

4. The method of claim 1, wherein performing the first set of one or more operations comprises using an XPath evaluation engine to evaluate any text descendants of the particular node.

5. The method of claim 1, wherein extracting the scalar value comprises converting the scalar value into a particular data type that is specified in the query or that is specified in an XML schema associated with the binary-encoded XML data.

6. The method of claim 5, wherein:

before converting, the data type of the scalar value is a string; and

the particular data type is one of a number data type, a date data type, a float data type, or a Boolean data type.

7. The method of claim 1, further comprising:

before receiving the query, storing XML data according to data types specified in an XML schema to which the XML data conforms, wherein converting the scalar value to a different data type is unnecessary.

8. The method of claim 1, wherein determining whether the particular node is simple is based on node information that is stored within the binary-encoded XML data or within an XML schema to which the binary-encoded XML data conforms.

10. The method of claim 1, wherein:

performing the first set of one or more operations comprises generating a state machine.

23. The one or more non-transitory method of claim 1, wherein the steps of determining and extracting are performed while streaming the binary-encoded XML data.

25. The method of claim 1, wherein:

extracting the scalar value of the particular node by performing the first set of one or more operations if the particular node is complex comprises reading an end element tag of the particular node; and

extracting the scalar value of the particular node if the particular node is simple is performed without having to read the end element tag of the particular node.

9. A computer-implemented method comprising:

determining that a node in an XML representation contains an XML value to extract, wherein the XML representation is a compact representation of an XML document that comprises textual XML data;

wherein the XML representation is a binary-encoding of one or more nodes of the XML document;

before extracting the XML value, determining whether the node is simple or complex, wherein a node is simple if the node has no child elements and no associated attributes, wherein a node is complex if the node has at least one child element or at least one attribute;

if it is determined that the node is complex, then extracting, from the XML representation, content of the node by performing a first set of one or more operations; and

if it is determined that the node is simple, then extracting, from the XML representation, content of the node without performing the first set of one or more operations;

wherein the method is performed by one or more computing devices.

11. The method of claim 9, wherein:

performing the first set of one or more operations comprises generating a state machine.

12. One or more non-transitory machine-readable storage media storing instructions which, when executed by one or more processors, cause:

receiving a query that requires one or more XML nodes that are binary-encoded;

in response to receiving the query, requesting binary-encoded XML data from one or more data sources, wherein the binary-encoded XML data is a compact binary representation of textual XML data;

determining that a particular node reflected in the binary-encoded XML data satisfies one or more criteria of the query;

after determining that the particular node satisfies one or more criteria of the query and before extracting content of the particular node, determining whether the particular node is simple or complex, wherein a node is simple if the node has no child elements and no associated attributes, wherein a node is complex if the node has at least one child element or at least one attribute;

if it is determined that the particular node is complex, then extracting, from the binary-encoded XML data, a scalar value of the particular node by performing a first set of one or more operations;

if it is determined that the particular node is simple, then extracting, from the binary-encoded XML data, a scalar value of the particular node without performing the first set of one or more operations.

13. The one or more non-transitory machine-readable storage media of claim 12, wherein extracting the scalar value comprises converting the scalar value of the particular node into a non-binary-encoded format.

14. The one or more non-transitory machine-readable storage media of claim 13, wherein converting the scalar value of the particular node into a non-binary-encoded format is performed after the scalar value is identified.

15. The one or more non-transitory machine-readable storage media of claim 12, wherein performing the first set of one or more operations comprises using an XPath evaluation engine to evaluate any text descendants of the particular node.

16. The one or more non-transitory machine-readable storage media of claim 12, wherein extracting the scalar value comprises converting the scalar value into a particular data type that is specified in the query or that is specified in an XML schema associated with the binary-encoded XML data.

17. The one or more non-transitory machine-readable storage media of claim 16, wherein:

before converting, the data type of the scalar value is a string; and

the particular data type is one of a number data type, a date data type, a float data type, or a Boolean data type.

18. The one or more non-transitory machine-readable storage media of claim 12, wherein the instructions, when executed by one or more processors, further cause:

before receiving the query, storing XML data according to data types specified in an XML schema to which the XML data conforms, wherein converting the scalar value to a different data type is unnecessary.

19. The one or more non-transitory machine-readable storage media of claim 12, wherein determining whether the particular node is simple is based on node information that is stored within a subset of the binary-encoded XML data or within an XML schema to which the binary-encoded XML data conforms.

20. The one or more non-transitory machine-readable storage media of claim 12, wherein:

performing the one or more operations comprises generating a state machine.

24. The one or more non-transitory machine-readable storage media of claim 12, wherein determining and extracting are performed while streaming the binary-encoded XML data.

26. The one or more non-transitory machine-readable storage media of claim 12, wherein:

extracting the scalar value of the particular node by performing the first set of one or more operations if the particular node is complex comprises reading an end element tag of the particular node; and

extracting the scalar value of the particular node if the particular node is simple is performed without having to read the end element tag of the particular node.

21. One or more non-transitory machine-readable storage media storing instructions which, when executed by one or more processors, cause:

determining that a node in an XML representation contains an XML value to extract, wherein the XML representation is a compact representation of an XML document that comprises textual XML data;

wherein the XML representation is a binary-encoding of one or more nodes of the XML document;

before extracting the XML value, determining whether the node is simple or complex, wherein a node is simple if the node has no child elements and no associated attributes, wherein a node is complex if the node has at least one child element or at least one attribute;

if it is determined that the node is complex, then extracting, from the XML representation, content of the node by performing a first set of one or more operations; and

if it is determined that the node is simple, then extracting, from the XML representation, content of the node without performing the first set of one or more operations.

22. The one or more non-transitory machine-readable storage media of claim 21, wherein:

performing the first set of one or more operations comprises generating a state machine.