842 (compression algorithm)

842, 8-4-2, or EFT is a data compression algorithm. It is a variation on Lempel–Ziv compression with a limited dictionary length. With typical data, 842 gives 80 to 90 percent of the compression of LZ77 with much faster throughput and less memory use. Hardware implementations also provide minimal use of energy and minimal chip area.

842 compression can be used for virtual memory compression, for databases — especially column-oriented stores, and when streaming input-output — for example to do backups or to write to log files.