An apparatus, system, and method are disclosed for efficient content indexing of streaming XML document content. A forest generator generates an XML pattern forest from a set of structured index path expressions, the XML pattern forest includes trees and twigs generated from structured index path expressions uniquely associated with a namespace indicator for an XML node. The XML node is identified in a stream of at least one XML document. A comparison module compares the XML node to nodes of trees and twigs of the XML pattern forest. A determination module determines a match between the XML node and an index node in one of a tree and a twig of the XML pattern forest. The index node has 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. A storage module stores an index entry for the XML node in response to the determined match, the index entry includes a XML document identifier, an XML node name, a namespace indicator for the XML node, and XML node content.