16. The method of claim 13 , wherein the cluster is generated at predetermined time intervals or corresponding to basic query.
13. A method of processing a data stream using a cluster query, the method comprising: generating at least one cluster for queries based on a commonality of words included in the queries; extracting a representative query for each generated cluster; in response to receiving a query, determining a cluster to which the received query belongs, and mapping the received query to a representative query of the determined cluster; executing the representative query from the determined cluster to determine an answer of the representative query based on the data stream; and providing the answer of the representative query as an approximate result of the received query instead of processing the received query, wherein the queries comprise a feature vector, and the cluster is generated based on the feature vector of the queries.