A first stream operator can receive a first tuple including a first set of attributes to be stored in a first window and a second tuple including a second set of attributes to be stored in a second window. The first window and the second window can each have an eviction policy. In response to triggering the eviction policy for the first window and the second window, the first tuple stored in the first window can be compared with the second tuple stored in the second window. Based upon the comparing, it can be determined that the first tuple and the second tuple go outside of a join threshold. In response to determining that the first tuple and the second tuple go outside of a join threshold, the eviction policy of the first window can be altered.