Delta encoding

Delta encoding is a way of storing or transmitting data as the differences, called deltas, between sequential pieces of data rather than as complete files. The general idea is also known as data differencing, and it is sometimes called delta compression, particularly where archival histories of changes are needed, as in revision control software. The differences are recorded in discrete files called deltas or diffs. When differences are small, for example a change of a few words in a large document or a few records in a large table, delta encoding greatly reduces data redundancy, and collections of unique deltas are substantially more space-efficient than their non-encoded equivalents. Logically, the difference between two values is the information needed to obtain one value from the other.