1. Field of the Invention
The present invention relates to an information retrieval system for retrieving information from a data base. More particularly it relates to an information retrieval system improved in efficiency by shortening the waiting time at retrieval and one capable of presenting information, if necessary, by processing the retrieval results of various formats obtained through retrieval so that they may be evaluated easily.
2. Description of the Related Art
Various kinds of inventions have been proposed with respect to the information retrieval technique for obtaining desired data by access to data bases dispersed on a network. A conventional technique of this kind is disclosed in, for example, Japanese Patent Publication Laid-Open (Kokai) No. Heisei 2-87274, "On-Line Information Retrieval System". The same publication discloses a system for obtaining desired data from a data base on a network, which comprises a communication means for gaining access to a data base on a network, an input means of a retrieval expression, a conversion means for converting the format of the received retrieval expression into one for use in a data base to be retrieved, and a means for storing and editing the data results retrieved by the use of the converted retrieval expression.
Another conventional technique of this kind is disclosed in, for example, Japanese Patent Publication Laid-Open (Kokai) No. Heisei 7-56932, "Information Retrieval System". The same publication discloses a system for obtaining desired data from a data base on a network, which comprises a for receiving a retrieval request for analyzing it, a for converting the format of the analyzed retrieval request into that one for use in a data base to be retrieved, a means for selecting a proper data base depending on the content of the retrieval request, and a means receiving retrieval results from the selected data base for evaluating them.
Further, various means to improve retrieval speed have been proposed in the conventional information retrieval techniques. A conventional technique of this kind is disclosed in, for example, Japanese Patent Publication Laid-Open (Kokai) No. Heisei 7-28836, "Data Base Retrieval Method and a Data Base System Using This Method". The same publication discloses a system for sharing the retrieval processing corresponding to a retrieval request among a plurality of retrieval server tasks so as to execute the retrieval processing in parallel, the system comprising a plurality of external storage operable in parallel and a plurality of retrieval server tasks for retrieving data individually from each external storage. In this way, many of the conventional techniques of this kind aim to improve the speed of the retrieval processing itself.
Further, swift and accurate evaluation of retrieval results is an important matter in the conventional information retrieval technique. Various techniques for reducing user's labor by devising the output format of retrieval results have been proposed. A conventional technique of this kind is discloses in, for example, Japanese Patent Publication Laid-Open (Kokai) No. Heisei 7-319905, "Information Retrieval System". The same publication discloses a system for supporting the operation of a user's focussing on desired data among the retrieval results, after data retrieval, a means for sorting retrieval results based on a predetermined viewpoint, a means for displaying the sort results simultaneously, and a means for displaying the details of some sort results selected from the displayed sort results.
The above-mentioned conventional information retrieval techniques, however, are insufficient to improve the retrieval speed and support the evaluation work of retrieval results.
When considering the access to a data base dispersed on a network, in order to improve the retrieval speed, it is necessary to do the retrieval processing in consideration of the difference in the response time per each data base and the difference in the burden of the network. However, these considerations are taken in none of the above mentioned conventional techniques. Even if the above-mentioned conventional system is used in gaining access to a plurality of data bases dispersed on a network, there is no use expecting substantial reduction in the retrieval time, with necessity of further improvement remaining there.
Since the system disclosed in the patent publication No. 2-87274 sequentially gains access to all the data bases, it can't make up for delays in the response time in the data bases.
In the system disclosed in the patent publication No. 7-56932, though data bases accessible depending on the content of a retrieval request are restricted, no consideration is taken in case of an extremely poor response occurring in some data base of the selected data bases to be retrieved. Therefore, it is insufficient to improve the retrieval speed and the waiting time.
The system disclosed in the patent publication No. 7-28836 can shorten the time required for retrieval processing itself. However, when retrieving a plurality of data bases, the system can't display the retrieval results until the retrieval result from the last data base is received, because the system displays the retrieval results sorted and integrated. In case of a poor response in a retrieving data base, the system is provided with no means for interrupting the retrieval processing. Therefore, a user must wait until the retrieval in a data base of the poorest response has been completed.
While, in case of access to a plurality of data bases, it is necessary to eliminate redundancy in retrieval results and standardize the display format of the retrieval results, in order to do efficient evaluation work of the retrieval results. The system disclosed in the patent publication No. 7-319905, however, has no consideration as for the overlapping retrieval results and it can't eliminate redundancy caused by the overlap of the retrieval results.
The system disclosed in the patent publication No. 2-87274 has no consideration for the difference in display format when searching for overlapping data, although it is provided with a function to eliminate the overlapping data. When judging whether it is the same retrieval result or not, the difference in the display formats of the retrieval results affects the judgement. Further, error compensation for searched overlapping data is not considered in the system.
The system disclosed in the patent publication No. 7-56932 can search for overlapping data by comparison among the obtained retrieval results. However, since it only makes a comparison among a plurality of retrieval results, it is difficult to recognize whether it is the same information as for the retrieval result obtained in a different display format.