Hitachi, Ltd.

Yuuya Isoda

Atsushi Tomoda

Kazutomo Ushijima

Hideo Aoki

Tsuyoshi Tanaka

Yohsuke Ishii

Tomohiro Hanai

To derive a query which can be joined and which gives non-zero pieces of data even if joined. A query generation assist method to assist generation of a query to extract data from a database includes: a first step of accepting, at the computer, a condition of extracting data to be acquired from the database as a data extraction condition; a second step of extracting, as graph data and at the computer, data which can be joined in data of the database; a third step of extracting subgraphs at the computer based on the data extraction condition from the graph data, and acquiring the subgraphs as query candidates; and a fourth step of calculating, at the computer, rank values of the query candidates and outputting the query candidates ranked according to the rank values.

Query generation assist method and query generation assist apparatus

A computer for executing processing through use of a database, the computer comprising: a processor including a cache memory; and a non-volatile memory coupled to the processor, the non-volatile memory having the database constructed thereon. The computer comprises: a database management module configured to execute processing on the database; and a write processing module configured to write data stored in the cache memory into the database. The write processing module writes data that is operated in the transaction processing into the database among data stored in the cache memory, in a case of receiving a commit request for transaction processing that uses the database.

Computer

A database management system generates a log each transaction during execution of a plurality of transactions and stores the generated logs in log storage areas. The database management system records sequence numbers of logs at least in the generated logs of transactions belonging to a set of transactions of which results are different depending on a transaction execution order.

Database management system and method

Provided is a log management method in which, with a computer system provided with a processor, a memory, and a storage device, the processor executes a prescribed process and stores in the storage device a log which includes a description of the process, said method comprising a first step of the processor generating the log which includes the description of the prescribed process, a second step of the processor writing the log to a log file of the storage device, and a third step of the processor determining the end of the log region which stores the log and writing same to the log file of the storage device.

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Tokyo, Japan

Yuuya Isoda