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

• US 5,940,836 A
• Filed: 04/21/1997
• Issued: 08/17/1999
• 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:
  US08/845,038
• Time in Patent Office: 848 Days
• Field of Search: 707/100, 707/101, 707/1, 707/2, 707/21, 707/104
• 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 data base retrieving device for retrieving a data base on the basis of a query, said full-text data base retrieving device comprising:

a full-text index having character location information representative of location of each of key character sequences of N characters that appear in said data base, where N is a positive integer, said character location information being produced in accordance with the sorts of said key character sequences and classified contexts which have classification numbers and each of which has any one of said key character sequences;

query memory means for memorizing an inputted query as a retrieval key character sequence;

separating means for separating said retrieval key character sequence into a plurality of retrieval key character sequences of N characters to extract contexts as extracted contexts from said retrieval key character sequence in accordance with said retrieval key character sequences;

context classifying means for classifying said extracted contexts into classified contexts having classification numbers, respectively;

index retrieving means for retrieving said full-text index in accordance with the sorts of said retrieval key character sequences and said classified contexts to read said character location information as a retrieval result out of said full-text index; and

detecting means for detecting appearance locations of said retrieval key character sequence in said full-text data base to produce said appearance locations as a detected result.

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

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

said context classifying means endowing said specific retrieval context with a specific one of said classification numbers in accordance with character codes 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 individually determined in accordance with an appearance frequency of each of said extracted sets in said data base.

4. 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.

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