A method of separating data blocks with stationary informational characteristics, including the steps of sequentially collecting statistics for small data blocks in an input data set, calculating the relative change in the estimated compression efficiency for a solid block currently being formed caused by merging its statistics with the statistics of a next small block, deciding whether the small block should be added to the solid block; for any block for which the decision is no, the block is used as the starting block of the next solid block to be formed. Auxiliary block data type detection is used to improve the method.