1. A method for processing a query, the method comprising: providing, in a database management system configured to store structured documents in their native format, an inverted multi-path index configured to store a plurality of path-value pairs and a selectivity factor for each of the path-value pairs based on a number of the structured documents that include one of the path-value pairs, wherein each path-value pair references at least one structured document stored in the database system and comprises an index path expression of an indexed element in a stored structured document and an indexed value associated with the indexed element; receiving, by an indexing engine in the database management system, a clause including a path expression-value pair comprising a path expression associated with an element of a structured document and a value, wherein the clause is included in a query for at least one structured document satisfying the clause; determining, by the indexing engine, that the clause can be processed by the inverted multi-path index; processing, by the indexing engine, the clause to identify a path-value pair in the inverted multi-path index matching the path expression-value pair of the clause; and identifying, by the indexing engine, the at least one structured document referenced by the matching path-value pair.
1. A method for processing a query, the method comprising: providing, in a database management system configured to store structured documents in their native format, an inverted multi-path index configured to store a plurality of path-value pairs and a selectivity factor for each of the path-value pairs based on a number of the structured documents that include one of the path-value pairs, wherein each path-value pair references at least one structured document stored in the database system and comprises an index path expression of an indexed element in a stored structured document and an indexed value associated with the indexed element; receiving, by an indexing engine in the database management system, a clause including a path expression-value pair comprising a path expression associated with an element of a structured document and a value, wherein the clause is included in a query for at least one structured document satisfying the clause; determining, by the indexing engine, that the clause can be processed by the inverted multi-path index; processing, by the indexing engine, the clause to identify a path-value pair in the inverted multi-path index matching the path expression-value pair of the clause; and identifying, by the indexing engine, the at least one structured document referenced by the matching path-value pair. 7. The method of claim 1 wherein the clause includes a first path expression-value pair joined with a second path expression-value pair, and wherein processing the clause includes: identifying a first path-value pair in the inverted multi-path index that matches the first path expression-value pair of the clause; identifying a second path-value pair in the inverted multi-path index that matches the second path expression-value pair of the clause; intersecting the at least one structured documents referenced by the first path-value pair with the at least one structured documents referenced by the second path-value pair; and identifying at least one common structured document referenced by the first path-value pair and the second path-value pair.