Full-text index producing device for producing a full-text index and full-text data base retrieving device having the full-text index

• US 6,189,006 B1
• Filed: 03/02/1999
• Issued: 02/13/2001
• Est. Priority Date: 04/19/1996
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Fukushima, Toshikazu
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): RONES, CHARLES
• Application Number:
  US09/260,535
• Time in Patent Office: 714 Days
• Field of Search: 709/227, 709/204, 707/104, 707/201, 707/6, 707/102, 707/103, 705/26, 455/414, 455/461, 395/101, 382/177, 382/311
• US Class Current: 1/1
• CPC Class Codes: G06F 16/319 Inverted lists
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99948 Application of database or data structure, e.g. distributed, multimedia, or image

Abstract

A full-text data base retrieving device retrieves a data base in accordance with a query. A full-text index has character location information representative of location of each of key character sequences of N characters that appear in the data base, where N is a positive integer. A query memory memorizes the query as a retrieval key character sequence. A separating section separates the retrieval key character sequence into a plurality of retrieval key character sequences of N characters to extract contexts as extracted contexts from the retrieval key character sequence in accordance with the retrieval key character sequences. A context classifying section classifies the extracted contexts into classified contexts having the classification numbers, respectively. An index retrieving section retrieves the full-text index in accordance with the sorts of the retrieval key character sequences and the classified contexts to read the character location information as a retrieval result out of the full-text index. A detecting section detects appearance locations of the retrieval key character sequence in the full-text data base to produce the appearance locations as a detected result.

Claims

1. A full-text index producing device for producing a full-text index, comprising:

extracting means for extracting from a full text database;

key character sequences of N characters as extracted sets, where N is a positive integer;

contexts having any one of said extracted sets; and

character location information representative of a respective location of each of said extracted sets;

context classifying means for classifying each of said contexts into a classified context, each said classified context having a respective classification number determined by an arithmetic or logical operation involving values of characters of said classified context; and

producing means for producing said full text index based on said character location information, sorts of said extracted sets, and said classified contexts.

2. A full-text index producing device as claimed in claim 1, wherein;

each of said contexts is defined by front characters of S in number positioned just before said extracted sets, and back characters of T in number positioned just after said extracted sets context, where each of S and T represents a positive number; and

said context classifying means endows said specific context with a specific one of said classification numbers in accordance with character codes of at least one of the group consisting of said front characters and said back characters, said specific classification number being defined by a predetermined upper limit value.

3. A full-text index producing device as claimed in claim 2, wherein said predetermined upper limit value is determined by the key character sort of each of said extracted sets.

4. A full-text index producing device as claimed in claim 3, wherein said key character sort is any one of Chinese character, Japanese cursive syllabary, and square Japanese syllabary.

5. A full-text index producing device as claimed in claim 2, wherein said predetermined upper limit value is individually determined in accordance with an appearance frequency of each of said extracted sets in said full text database.

6. A full-text index producing device as claimed in claim 1, wherein said producing means compresses said character location information into compressed character information.