2. The method of claim 1 , wherein said filtering comprises: querying an inverted index generated on the first set of documents using the set of covering token sets to determine a set of document identifiers for a subset of the documents in the first set; retrieving a subset of documents from the first set identified by the set of document identifiers; and performing entity string matching on the retrieved subset of documents.
2. The method of claim 1 , wherein said filtering comprises: querying an inverted index generated on the first set of documents using the set of covering token sets to determine a set of document identifiers for a subset of the documents in the first set; retrieving a subset of documents from the first set identified by the set of document identifiers; and performing entity string matching on the retrieved subset of documents. 4. The method of claim 2 , wherein said querying comprises: querying the inverted index with a plurality of batch queries, each batch query using a subset of the set of covering token sets to query the inverted index.