System and method for searching dates efficiently in a collection of web documents

A date querying system processes free-form text in documents to identify and locate some or all of the dates in the documents using extended regular expression matching to capture various date formats. The system packages a canonicalized format of each identified date to support various types of queries such as, for example, specific date querying, hierarchical date querying, range date querying, proximity queries comprising a date and any keywords, and any combination of types of queries. The system scans a document to identify the various format dates occurring in the document, disambiguates the resulting occurrences of dates, and canonicalizes the dates according to one or more predetermined formats.