Sort order preservation method used with a static compression dictionary having consecutively numbered children of a parent

摘要

A method of performing Ziv-Lempel type data compression while preserving in the compressed records any sort ordering of the uncompressed records. The method assigns the necessary ordered numbering to the code words for character strings in a static compression dictionary even though the dictionary is structured so that all children of the same parent have sequential index numbering. The children of a parent are in collating sequence order, and adjacent children that are nonadjacent in the collating sequence have a conceptual epsilon entry between them, which entry represents a match on the parent and a direction in the collating sequence. Code words for actual children are formed by using a dictionary entry index to locate a translation table entry containing a code word. Code words for epsilon entries are formed by using an entry index for an actual child to locate a translation table entry and then adding or subtracting one to or from the code word in the entry.