12. A method comprising: receiving, from a first user, a search query to search for document information in a database, the database including an index data structure; determining that terms of the search query are in accordance with dictionary information corresponding to the first user, the dictionary information including a first list of compatible query operators; applying the search query to the index data structure in the database to identify the document information; and sending an electronic interface to the first user, the electronic interface including the document information.
12. A method comprising: receiving, from a first user, a search query to search for document information in a database, the database including an index data structure; determining that terms of the search query are in accordance with dictionary information corresponding to the first user, the dictionary information including a first list of compatible query operators; applying the search query to the index data structure in the database to identify the document information; and sending an electronic interface to the first user, the electronic interface including the document information. 18. The method of claim 12 , wherein the search query is arranged as an expression tree including at least one child node coupled to at least one parent node and wherein data included in the at least one child node is an input to an operator included in the at least one parent node.