8. A computer program product comprising a non-transitory computer readable storage medium having computer usable program code executable to perform operations for content indexing of streaming Extensible Markup Language (XML) document content, the computer program product comprising: a scanner configured to scan a streaming XML document in a stream of XML documents, the streaming XML document streamed in document order from a stored intact hierarchical document according to XML tree traversal protocol; an identification module configured to identify an XML node of the streaming XML document, the XML node comprising one of an XML document element node and an XML document element attribute node, the streaming XML document comprising two or more namespace indicators, the XML node associated with a first namespace indicator of the two or more namespace indicators; a forest generator configured to generate a first portion of a XML pattern forest for the first namespace indicator using a first set of structured index path expressions, the XML pattern forest comprising at least one of a tree and a twig generated from at least a portion of one or more structured index path expressions of the first set of structured index path expressions; a comparison module configured to compare the XML node to nodes of the first portion of the XML pattern forest; a determination module configured to determine a match between the XML node and an index node in one of a tree and a twig of the first portion of the XML pattern forest, the index node having a path from an ancestor node to the index node that matches the axis steps of at least one of the structured index path expressions for the first namespace indicator; and a storage module configured to store an index entry for the XML node in response to the determined match, the identification module further configured to identify a second XML node associated with a second namespace indicator; and the forest generator further configured to generate a second portion of the XML pattern forest for the second namespace indicator using a second set of structured index path expressions.
8. A computer program product comprising a non-transitory computer readable storage medium having computer usable program code executable to perform operations for content indexing of streaming Extensible Markup Language (XML) document content, the computer program product comprising: a scanner configured to scan a streaming XML document in a stream of XML documents, the streaming XML document streamed in document order from a stored intact hierarchical document according to XML tree traversal protocol; an identification module configured to identify an XML node of the streaming XML document, the XML node comprising one of an XML document element node and an XML document element attribute node, the streaming XML document comprising two or more namespace indicators, the XML node associated with a first namespace indicator of the two or more namespace indicators; a forest generator configured to generate a first portion of a XML pattern forest for the first namespace indicator using a first set of structured index path expressions, the XML pattern forest comprising at least one of a tree and a twig generated from at least a portion of one or more structured index path expressions of the first set of structured index path expressions; a comparison module configured to compare the XML node to nodes of the first portion of the XML pattern forest; a determination module configured to determine a match between the XML node and an index node in one of a tree and a twig of the first portion of the XML pattern forest, the index node having a path from an ancestor node to the index node that matches the axis steps of at least one of the structured index path expressions for the first namespace indicator; and a storage module configured to store an index entry for the XML node in response to the determined match, the identification module further configured to identify a second XML node associated with a second namespace indicator; and the forest generator further configured to generate a second portion of the XML pattern forest for the second namespace indicator using a second set of structured index path expressions. 12. The computer program product of claim 8 , wherein the forest generator comprises a completion module configured to identify a second streaming XML document in the stream of XML documents, and discard the XML pattern forest in response to identifying the second streaming XML document.