842 (compression algorithm)

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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.^[1] 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.