1. A computer implemented method of data management, comprising the steps of: pre-selecting, at a processing unit, a portion of a plurality of windows of data in a data stream using a first content-defined selecting function that includes a boxcar sum function, an multiplicative linear congruential generator (MLCG) function, or a rolN-xor function; and selecting, at the processing unit, a subset of the portion of the plurality of windows pre-selected using a second content-defined selecting function to maximize a given characteristic, wherein the first content-defined selecting function is faster at selecting a data block boundary than is the second content-defined selecting function.