INFORMATION RETRIEVAL DEVICE, INFORMATION RETRIEVAL METHOD AND INFORMATION RETRIEVAL PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide an information retrieval device capable of executing retrieval processing at high speed without consuming a lot of resources. SOLUTION: This information retrieval device 1 has: a retrieval condition acquisition means 10 for acquiring a retrieval condition; an index acquisition means 13 for acquiring a bitmap table from a topmost stage to a downmost stage in turns based on the retrieval condition from an index wherein the bitmap tables each hierarchically formed by degenerating or compressing the bitmap table are layered in a multistage state; a decompression means 14 for decompressing data of the compressed bitmap table when the bitmap table is compressed; a bitmap calculation means 15 for extracting a bitmap string corresponding to the retrieval condition from the bitmap table to the downmost stage in turns in the decompressed bitmap table, and performing a bitwise operation to calculate a bitmap; and a bitmap correspondence information extraction means 12 for extracting a document corresponding to a position allocated with a bit from a plurality of documents in the bitmap calculated in the downmost stage. COPYRIGHT: (C)2009,JPO&INPIT