Parent-child query indexing for XML databases

A method for creating a database of step queries and step query results for a document of elements, the method comprising:

• determining relationships between a plurality of elements from the document of elements;
• generating step queries from the relationships;
• generating step query results for the step queries, wherein a step query result for a step query corresponds to one or more elements in the document of elements for the step query;
• and
• storing the step queries and corresponding step query results in the database, wherein the stored step query results are usable to generate a result for a main query, wherein the main query can be reduced to a plurality of step queries that correspond to the stored step queries.

A query processor for processing a query for a document of elements, the processor comprising:

• a document processor configured to receive the document of elements and pre-compute a plurality of step queries and corresponding step query results from the document of elements;
• a database for storing the pre-computed plurality of step queries and corresponding step query results;
• and
• a query processor configured to receive the query, generate a plurality of step queries from the query, and generate a result for the query using the step query results retrieved from the database that correspond to the plurality of step queries.

A method for processing queries for a document of elements, the document including a plurality of subsections, each subsection including at least a portion of elements in the document, the method comprising:

• receiving a query for a path of elements in the document of elements;
• determining a plurality of step queries from the query, each step query including at least a part of the path of elements;
• for each step query in the plurality of step queries, determining one or more subsections that include elements that correspond to a step query;
• and
• determining at least one subsection that includes the path of elements of the query.