Abstract: Increasing data storage efficiency includes receiving an amendment to a set of data objects. The amendment includes new or changed content relative to an earlier version of the set of data objects. The amendment includes one or more data lookup tables. The set of data objects includes data blocks associated with the data lookup tables. The set of data objects is examined to identify data ranges (e.g., byte ranges) that are not referenced in the set of data lookup tables of the amendment. In data ranges that are identified as not referenced in the data lookup tables, the data is replaced with data that is more compressible (for example, the range may be filled with zero values). The set of data objects may be compacted by compressing data including the identified unreferenced data ranges.