A method for managing a data storage system, comprising: storing a first set of explicitly enumerated data values included in a data stream from at least one electronic device in a first window data structure comprising a sliding window associated with a first time span; storing one or more sets of summary statistics in a second set of window data structures comprising a sequence of decayed windows , wherein each decayed window is associated with a time span older than the first time span, and the one or more sets of summary statistics are based on a second set of data values included in the data stream; storing a third set of explicitly enumerated data values included in the data stream in a third set of window data structures comprising at least one landmark window , wherein each data value of the third set of explicitly enumerated data values is annotated; receiving a new data value; if the new data value is annotated , appending the new data value to one of the at least one landmark windows or a new landmark window; if the new data value is not annotated , enqueuing the new data value in the sliding window; in response to determining a current size of the sliding window exceeds a pre-determined threshold value: dequeuing an oldest data value maintained by the sliding window; updating the one or more sets of summary statistics maintained by the sequence of decayed windows to subsume the oldest data value into the sequence of decayed windows, and merging a pair of consecutive decayed windows included in the sequence of decayed windows in response to determining a decay function is satisfied, wherein each window data structure is maintained on at least one storage device of the data storage system. storing a first set of explicitly enumerated data values included in a data stream from at least one electronic device in a first window data structure comprising a sliding window associated with a first time span; storing one or more sets of summary statistics in a second set of window data structures comprising a sequence of decayed windows , wherein each decayed window is associated with a time span older than the first time span, and the one or more sets of summary statistics are based on a second set of data values included in the data stream; storing a third set of explicitly enumerated data values included in the data stream in a third set of window data structures comprising at least one landmark window , wherein each data value of the third set of explicitly enumerated data values is annotated; receiving a new data value; if the new data value is annotated , appending the new data value to one of the at least one landmark windows or a new landmark window; if the new data value is not annotated , enqueuing the new data value in the sliding window; in response to determining a current size of the sliding window exceeds a pre-determined threshold value: dequeuing an oldest data value maintained by the sliding window; updating the one or more sets of summary statistics maintained by the sequence of decayed windows to subsume the oldest data value into the sequence of decayed windows, and merging a pair of consecutive decayed windows included in the sequence of decayed windows in response to determining a decay function is satisfied, wherein each window data structure is maintained on at least one storage device of the data storage system. <EOS>