Database system and a method of data retrieval from the system

• US 6,681,227 B1
• Filed: 11/18/1998
• Issued: 01/20/2004
• Est. Priority Date: 11/19/1997
• Status: Expired due to Term

• Current Assignee: NS Solutions Corporation (Nippon Steel Corporation)
• Original Assignee: NS Solutions Corporation (Nippon Steel Corporation)
• Inventors: Kojima, Kazuhito, Yoshikura, Mitsuru, Uesugi, Hiromoto
• Primary Examiner(s): Pardo, Thuy N.
• Application Number:
  US09/195,099
• Time in Patent Office: 1,889 Days
• Field of Search: 707/1, 707/3, 707/6, 707/10, 707/104, 707/102, 709/203, 709/2, 709/7, 395/200.47
• US Class Current: 1/1
• CPC Class Codes: G06F 16/907 Retrieval characterised by using metadata, e.g. metadata not derived from the content or metadata generated manually
• CPC Class Codes: G06F 16/951 Indexing; Web crawling techniques
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

Since metadata pertaining to real data stored in at least one database (DB) are collected and managed at a single meta DB server, and metadata that match a retrieval request are extracted by search of the meta DB server, even when a plurality of DBs and DB servers for managing DBs are present on a network, all metadata that match the retrieval request can be extracted independently of which DBs metadata pertain to. Hence, all data that match a retrieval request can be obtained from a single server independently of the actual locations of the distributed DBs and DB servers.

Claims

1. A database system built by distributing one or more databases and one or more first servers which search the databases for real data on a network, said first servers comprising first metadata saving means for saving metadata which pertain to real data stored in said one or more databases, wherein the database is a relational database, said system comprising:

a metadata database for collecting and managing metadata saved in said first metadata savings means;

metadata retrieval means for extracting metadata which matches a request from a user terminal connected to the network by searching said metadata database in response to said request;

real data retrieval means for directly retrieving real data corresponding to the extracted metadata from said one or more databases,

wherein said real data retrieval means bypasses said metadata retrieval means when directly retrieving said real data,

wherein said metadata contains at least information indicating a location of the database or the first server, and contents of real data in the database;

table extraction means for extracting one table including columns that store data to be retrieved from a plurality of tables in the database;

column exclusion means for excluding columns of the table extracted by said table extraction means and columns on other tables which store the same data contents as data contents of the columns on the extracted table from columns to be extracted in subsequent processing; and

table joining means for joining the tables extracted in turn by said table extraction means when the processing of said table extraction means and the processing of said column exclusion means have been repeated until all the columns including data to be retrieved are analyzed, and the real data is retrieved from the tables joined by said table join means.

2. A system according to claim 1, wherein said metadata database and metadata retrieval means are located in one or more second servers different from the first servers.

3. A system according to claim 2, wherein the second server comprises means for acquiring corresponding metadata when data stored in said metadata saving means of said first servers has been updated.

4. A system according to claim 2, wherein the second server comprises means for acquiring data stored in said metadata saving means of said first servers at a predetermined time interval.

5. A system according to claim 1, wherein the user terminal comprises:

means for inputting a retrieval request of the metadata;

means for inputting a retrieval condition upon retrieving real data on the database using a retrieval result of the metadata supplied from said metadata retrieval means; and

means for transferring the input retrieval condition to the first server indicated by the extracted metadata as a retrieval request.

6. A system according to claim 5, wherein said means for inputting a retrieval condition is an operational screen provided by said second servers.

7. A system according to claim 5, wherein the first server comprises means for converting the retrieval request to the database transferred from the user terminal into a format concordant with the database to be accessed.

8. A system according to claim 1, wherein said metadata has a structure divided into a plurality of layers.

9. A method of retrieving real data by a user from a network having a at least one distributed database having at least one database server associated therewith, the method comprising:

creating composite metadata relating to real data in all of the at least one distributed database;

storing the created composite metadata in a metadata database;

issuing an inquiry from the user to a server containing the metadata database;

searching the metadata database based upon the inquiry;

transmitting a search result from the server to the user;

bypassing the server containing the metadata database and issuing a real data retrieval request from the user to said at least one database server based upon the search result;

searching the at least one distributed database;

transmitting a retrieval result of real data to the user from said at least one distributed database; and

updating the created composite metadata,

wherein said updating includes checking for expiration of an update interval associated with said at least one database server.

10. The method of claim 9, further comprising registering information required for acquiring metadata from each of said at least one distributed database.

11. The method of claim 10, wherein said step of registering includes at least registering a URL or a database server location.

12. The method of claim 10, wherein said step of registering includes registering an update interval for the at least one database server.

13. The method of claim 9, wherein said updating includes sending a metadata update check from the server to said at least one database server.

14. The method of claim 9, wherein said updating includes saving updated metadata in the metadata database and recording a time of update of the metadata.

15. The method of claim 9, further comprising, before said step of issuing a retrieval request from the user to said at least one database server, verifying that the user is satisfied with the search result transmitted from the server to the user.

16. The method of claim 9, further comprising translating the retrieval request from the user to said at least one database server into a format compatible with a distributed database associated with said at least one database server.

17. The method of claim 9, wherein said step of transmitting a search result from the server to the user includes sending a URL of a database server to the user.

18. The method of claim 9, wherein said step of transmitting a search result from the server to the user includes sending a retrieval condition statement to the user.

19. The method of claim 9, wherein said step of issuing an inquiry from the user to a server containing the metadata database at least includes designating a keyword.