1. A method of classifying a document using a duplicate detector and an inductive classifier, the method comprising: receiving, at the inductive classifier, a training set of documents of known classification; generating, at the inductive classifier, attribute information based on the set of training documents of known classification; developing, at the inductive classifier, a classification model based on the attribute information; providing the attribute information from the inductive classifier to the duplicate detector, the duplicate detector being configured to determine whether two or more data items are near duplicates; generating, at the duplicate detector, a lexicon of attributes based on the attribute information received from the inductive classifier; receiving, at the duplicate detector, a set of documents of known classification; calculating, at the duplicate detector, class signatures based on the set of documents of known classification and the lexicon of attributes; receiving, at the duplicate detector, an unknown document; generating, at the duplicate detector, a query signature based on the unknown document and the lexicon of attributes, wherein the generating of the query signature comprises: determining unique attributes in the unknown document; determining an intersection between the unique attributes in the unknown document and the lexicon; and calculating the query signature based on the intersection; comparing, at the duplicate detector, the query signature to the class signatures to determine whether the query signature matches a class signature; when the query signature matches a class signature, indicating the unknown document has a class of the document corresponding to the class signature that matches the query signature; and when the query signature does not match a class signature: providing the unknown document to the inductive classifier; and applying, at the inductive classifier, the classification model to the unknown document to determine a class for the unknown document.