A search engine provides efficient and scalable search queries for documents using a document summaries index file structure. The document summaries index file structure comprises an index portion and a records portion. The index portion contains a plurality of document identifiers, each of which is linked to a record in the record values portion. The records portion includes a document summary that may include a number of fields, including a name-length, name, type, and value-length, and value. Each record value is searched to determine if the contents matches criteria in the search request. The document summaries index file can be modified to add new indexable criteria in a scalable and efficient manner.