| 摘要 |
PROBLEM TO BE SOLVED: To provide the method and system for compressing data, in which replacement of a sub string of data characters by a replacement code is included. SOLUTION: A replacement code includes reference to a sub string of a data character at a preceding position in matching with a sub string of a data character, that is being replaced at a 1st position and an instruction of a size of a sub string to be replaced. This reference indicates an offset in a reverse direction from that of the 1st position to the preceding position. The offset in the reverse direction, the length of the sub string, the length of a continuous literal character, and the literal character itself are Huffman-coded to reduce the data size. When data compression method to geographical data are applied, a plurality of parts of a data record can use the same Huffman tree, by storing the Huffman tree decoding the coded character to areas other than the areas for a database including the data compressed through Huffman coding.
|
