Database system, database server, and method of controlling the operation of a database server

Abstract

A database system is provided with a search unit for searching image attribute information that has been stored in a relational database management system. A search interface is provided between the search unit and a command execution unit, which applies a search command to the search unit. The command execution unit and search unit can be connected in detachable fashion. Thus a search unit that has been connected to the command execution unit can be replaced by detaching it and connecting a search unit that employs another search technique.

1 - 3 . (canceled)  
     
     
         4 . A database server comprising: 
 a first receiving device for receiving a search command transmitted via a network;    a search device for searching the database based upon the search command received by said first receiving device;    a first determining device for determining whether the search command, which has been received by said first receiving device, can be transmitted to another database server;    a transmitting device for transmitting the received search command to said another database server when it is determined that the received search command can be transmitted to said another database server by said first determining device;    a second receiving device for receiving data, which represents search results, transmitted from said another database server in accordance with transmission of the search command to said another database server by said transmitting device; and    an output device for outputting, in mutually correlated form, data representing search results obtained by the search by said search device and data representing search results received by said second receiving device.    
     
     
         5 . A method of controlling operation of a database server comprising: 
 receiving a search command transmitted via a network;    searching a database based upon the received search command;    determining whether the received search command can be transmitted to another database server;    transmitting the received search command to said another database server when it is determined that the received search command can be transmitted to said another database server:    receiving data, which represents search results, transmitted from said another database server in accordance with transmission of the search command to said another database server; and    outputting, in mutually correlated form, data representing search results obtained by the search and data representing received search results.    
     
     
         6 . The database server according to  claim 4 , wherein 
 the search command is accompanied by data for determining whether the search command can be transmitted to said another database server, and    said first determining device determining whether the search command can be transmitted based upon the accompanying data.    
     
     
         7 . The database server according to  claim 4 , further comprising: 
 a second determining device for determining whether the data, which has an expression format indicated by the received search command by said first receiving device, is stored in the database;    a generating device for generating the data having the expression format when it is determined that the data having the expression format is not stored in the database by said second determining device; and    a storing device for storing the data generated by the generating device in the database.    
     
     
         8 . The database server according to  claim 6 , further comprising: 
 a second determining device for determining whether the data, which has an expression format indicated by the received search command by said first receiving device, is stored in the database;    a generating device for generating the data having the expression format when it is determined that the data having the expression format is not stored in the database by said second determining device; and    a storing device for storing the data generated by the generating device in the database.    
     
     
         9 . The database server according to  claim 4 , wherein said transmitting device transmits the received search command to a plurality of other database servers.  
     
     
         10 . The method of controlling operation of a database server according to  claim 5 , wherein said determining whether the search command can be transmitted to another database server is based upon data accompanying the search command for determining whether the search command can be transmitted.  
     
     
         11 . The method of controlling operation of a database server according to  claim 5 , further comprising: 
 determining whether the data, which has an expression format indicated bY the received search command, is stored in the database;    generating data having the expression format when it is determined that the data having the expression format is not stored in the database; and    storing the generated data in the database.    
     
     
         12 . The method of controlling operation of a database server according to  claim 10 , further comprising: 
 determining whether the data, which has an expression format indicated by the received search command, is stored in the database;    generating data having the expression format when it is determined that the data having the expression format is not stored in the database; and    storing the generated data in the database.    
     
     
         13 . The method of controlling operation of a database server according to  claim 5 , wherein the received search command is transmitted to a plurality of other database servers.  
     
     
         14 . A database server comprising: 
 means for receiving a search command transmitted via a network;    means for searching a database based upon the received search command;    means for determining whether the received search command can be transmitted to another database server;    means for transmitting the received search command to said another database server when it is determined that the received search command can be transmitted to said another database server;    means for receiving data, which represents search results, transmitted from said another database server in accordance with transmission of the received search command to said another database server; and    means for outputting, in mutually correlated form, data representing search results obtained by the search by said search device and data representing received search results.    
     
     
         15 . The database server according to  claim 14 , wherein 
 the search command is accompanied by data for determining whether the search command can be transmitted to said another database server, and    said determining means determines whether the search command can be transmitted based upon the accompanying data.    
     
     
         16 . The database server according to  claim 14 , further comprising: 
 means for determining whether the data, which has an expression format indicated by the received search command by said means for receiving said search command, is stored in the database;    means for generating the data having the expression format when it is determined that the data having the expression format is not stored in the database by said means for determining whether the data is stored in the database; and    means for storing the data generated by the generating means in the database.    
     
     
         17 . The database server according to  claim 15 , further comprising: 
 means for determining whether the data, which has an expression format indicated by the received search command by said means for receiving said search command, is stored in the database;    means for generating the data having the expression format when it is determined that the data having the expression format is not stored in the database by said means for determining whether the data is stored in the database; and    means for storing the data generated by the generating means in the database.    
     
     
         18 . The database server according to  claim 14 , wherein said transmitting means transmits the received search command to a plurality of other database servers.