1. A method for processing a stream of tuples, each tuple containing one or more attributes, comprising: receiving the stream of tuples to be processed by a plurality of processing elements operating on one or more computer processors; processing, with a first processing method, a group of tuples from the stream of tuples into a grouping window, wherein the first processing method includes: identifying a membership condition, determining whether the membership condition is met by a tuple from the stream of tuples, evicting the tuple from the grouping window in response to the membership condition being unmet, and including the tuple in the grouping window in response to the membership condition being met, and processing, with a second processing method, a subgroup of tuples from the group of tuples into a subgrouping window, wherein the second processing method includes: identifying a sub-membership condition, determining whether the sub-membership condition is met by a tuple from the group of tuples, wherein the membership condition and the sub-membership condition are not the same condition type, and including the tuple in the subgrouping window in response to the sub-membership condition being met.