Database system providing direct access for reads and indirect locked access for writes and reads in which an error was detected in previous attempt

A method of sharing a database between a plurality of processors with less overhead in a database system, the method comprising the steps of:

• generating a first search request in accordance with a user program executed in a first processor of the plurality of processors;
• managing selective exclusive access control over said database with a second processor of said plurality of processors;
• directly accessing the database by said first processor without exclusive control over the database in accordance with the generated first search request when the generated first search request is one of a plurality of first predetermined requests not accompanying a write operation to the database;
• transmitting the generated first search request from the first processor to the second processor as a particular request when the generated first search request is one of a plurality of second predetermined requests accompanying a write operation to the database;
• indirectly accessing the database by the first processor, through said second processor with the exclusive control, in response to the particular request;
• examining whether consistency exists between data searched in accordance with the first search request and first storage managing information of the data, the generated first search request being a request included in the plurality of first predetermined requests not accompanying a write operation to the database;
• transmitting the first search request is the particular request from the first processor to the second processor when the inconsistency is detected;
• and,
• transmitting the searched data from the second processor to the first processor.

A database system comprising:

• database means for storing a database;
• log means for storing database access log;
• managing processor means coupled to said database means and to said log means, for managing said database means, generating a first request in accordance with a first user program executed in the managing processor means, accessing said database means in accordance with the generated first request, receiving a particular request to access said database means in response to the received particular request, and updating the database access log in said log means when one of the first request and the particular request is one of a group of first predetermined requests associated with update processing of said database;
• and
• processing means coupled to said database means, said log means and said managing processor means, for generating a second request in accordance with a second user program executed in the processor means, directly accessing said database means in accordance with the generated second request when the generated second request is one of a group of second predetermined requests, processing for each of said group of second predetermined requests incurring no change in contents of said database, transmitting the generated second request to said managing processor means as the particular request when the generated second request is one of said group of first predetermined requests;
• the processor means comprising means, when the generated second request is a first search request included in said group of second predetermined requests, for i) transmitting the first search request as the particular request to said managing processor means, when a contradiction is detected between data searched for in accordance with the first search request and first storage managing information of the data, and for ii) receiving the searched data from said managing processor means;
• and
• said managing processor means comprising means for accessing said database means in response to the first search request to transmit the searched data to said processor means.

A database system comprising:

• database means for storing a database;
• exclusive control means responsive to an inputted access request, for performing exclusive control over said database means and granting an access permission;
• managing processor means coupled to said database means and to said exclusive control means, for managing said database means, generating a first request for access to said database in accordance with a first user program executed in the managing processor, directly accessing said database means in accordance with the generated first request when the generated first request is one of a first request group, wherein processing for each request in said first request group results in no change in the contents of the said database, outputting one of the first request generated in the managing processor means and particular request inputted into the managing processor means to said exclusive control means to acquire said access permission when the generated first request is one of a second request group, each request in said second request group being associated with an update processing of said database, and indirectly accessing said database means through said exclusive control means in accordance with said access permission and one of the generated first request belonging to said second request group and the particular request;
• and,
• processing means coupled to said database means, said exclusive control means and said managing processor means, for generating a second request in accordance with a second user program executed in the processing means, directly accessing said database means in accordance with the second request when the generated second request is one of said first request group and outputting the generated second request to said managing processor means as the particular request indirectly accessing said database means through said exclusive, control means when the generated second request is one of said second request group;
• wherein said processing means comprises means, when the generated second request is a first search request included in the first request group, for outputting the first search request as the particular request to said managing processor means when a contradiction is detected between data searched for in accordance with the first search request and managing information of the data in said database means, and for receiving the searched data from said managing processor means;
• and said managing processor means further comprising means for searching said database means for data to transmit the searched data to said processing means.

A method of sharing a database with reduced overhead in a database system, the method comprising the steps of:

• generating requests in accordance with user programs executed by each of plurality of processors;
• examining whether each generated request is one of a predetermined request group associated with a write operation to the database;
• executing processing associated with the generated requests for the database, while performing exclusive control by a managing processor which manages the database, when the generated requests are one of the predetermined request group associated with the write operation to the database;
• directly executing the processing associated with the generated requests for the database by each processor of the plurality of processors which generates the requests, without performing the exclusive control by the managing processor, when the generated request is not one of the predetermined request group associated with the write operation to the database;
• examining whether a contradiction exists between data searched for in accordance with a generated first search request and managing information of the data, the generated first search request not being a search request included in the predetermined request group;
• and,
• executing processing associated with the first search request for the database by the managing processor while executing the exclusive control for obtaining data as a search request included in the predetermined request group when the contradiction is detected.

A database system comprising:

• database storage means for storing a database;
• managing processor means coupled to said database storage means, for selectively and exclusively managing said database storage means by selectively and exclusively controlling updates to said database responsive to a first update request;
• and,
• processor means coupled to said database storage means and to said managing processor means for executing a program for processing data, the processor means including i) means for directly accessing said database in accordance with said program executed when the access is a read-type access, ii) means for indirectly accessing said database through said managing processor means in accordance with said program executed when the access is an update-type access by generating said first update request before update-type accessing the database, and iii) means for indirectly accessing said database through said managing processor means in accordance with said program executed when the access is a read-type access in response to an access error being detected in a previous direct access.

A database system comprising:

• first database storage means for storing a first database;
• second database storage means for storing a second database;
• first managing processor means coupled to said first and second database storage means, for exclusively managing said first database storage means by selectively and exclusively controlling updates to said first database responsive to a first update request;
• second managing processor means coupled to said first and second database storage means, for selectively and exclusively managing said second database storage means by exclusively controlling updates to said second database responsive to a second update request;
• first processor means in said first managing processor means for executing a first program for processing data, the first processor means including i) means for directly accessing said first and second database storage means in accordance with said first program executed when the access is a read-type access, ii) means for indirectly accessing said first and second database storage means through said first and second managing processor means respectively in accordance with said first program executed when the access in an update-type access by generating said first update request before update-type accessing the first and second database storage means and iii) means for indirectly accessing said first and second database storage means through said first and second managing processor means respectively in accordance with said first program executed when the access is a read-type access in response to an access error being detected in a previous direct access;
• and,
• second processor means in said second managing processor means for executing a second program for processing data, the second processor means including i) means for directly accessing said first and second database storage means in accordance with said second program executed when the access is a read-type access, ii) means for indirectly accessing said first and second database storage means through said first and second managing processor means respectively in accordance with said second program executed when the access is an update-type access by generating said second update request before update-type accessing the first and second database storage means and iii) means for indirectly accessing said first and second database storage means through said first and second managing processor means respectively in accordance with said second program executed when the access is a read-type access in response to an access error being detected in a previous direct access.