A request handler may determine a query of a data stream management system (DSMS), wherein the query includes a plurality of operators being configured to execute the query collaboratively within the DSMS, and wherein stored stream-related data includes operator-associated windows of state data from the stream data, the request handler being further configured to determine a new query having new windows corresponding to the windows of the original query. A windows sorter may sort the new windows from longest duration to shortest duration to obtain a sorted new windows list. A migration estimator may calculate individual migration times for migrating state data from each window to its corresponding new window, beginning with the longest new window of the sorted new windows list. A migration aggregator may aggregate the individual migration times to obtain a total migration time for the new query.