Hitachi, Ltd.

The University of Tokyo

Other

Masaru Kitsuregawa

Kazuo Goda

Kazuhiko Mogi

Nobuo Kawamura

Shinji Fujiwara

Akira Shimizu

Yuto Hayamizu

Norifumi Nishikawa

Seisuke Tokuda

Michiko Yoshida

Hideomi Idei

Yuya Isoda

Kouji Kimura

Hiroyuki Yamada

Mayuko Ozawa

Takuya Isozaki

Makoto Ootahara

Norifuml Nishikawa

Masashi Toyoda

Taro Fujimoto

The scanning range of an inner table can be limited in the join processing irrespective of the existence of search conditions or a partition key, and the performance of the join processing can be improved. There is a column range index representing a range of values stored in a table. When a join result of a current stage is an outer table related to a join of a next stage in a join of each stage of the join processing, a database management apparatus identifies whether there is a possibility that an inner table related to a join of a next stage includes a hit record in an inner table related to a join of a current stage based on a column range index corresponding to a join column of a current stage and a column range index corresponding to a join column of a next stage.

Database management apparatus and method

A database system includes a plurality of DBMSs included in a plurality of nodes. Each DBMS is a first or a second DBMS. The first DBMS transfers a search query and does not execute data retrieval, and the second DBMS executes data retrieval. The plurality of nodes configure one or more node groups. Each node group includes a first node and one or more second nodes. In each node group, the first node is a logical computer that provides a first storage area and executes a first DBMS and the second node is a logical computer that provides a second storage area and executes a second DBMS, each node in the node group stores the same database therein, and data retrieval from the database in the node group is executed by one or more second DBMSs in the node group.

Database system and query execution method

The database management system (DBMS) receives a first instruction specifying anonymization rule information corresponding to a column of the relation table, among anonymization rule information that is present for each column included in the relation table and shows a plurality of generalization rules. The DBMS reads the column from the relation table in response to the first instruction, and generates a temporary result obtained by generalizing each attribute value of the column based on any of a plurality of generalization rules. The DBMS generates an aggregate result obtained by aggregating the temporary result. The DBMS generates an anonymization method including generalization information indicating a correspondence relationship of each attribute value of the column and any of the plurality of generalization rules when the aggregate result satisfies a disclosure rule. The DBMS generates anonymization information as a result of processing the relation table based on the first anonymization method.

Database management system and database processing method

A database management system (DBMS) generates a query execution plan including information representing one or more database (DB) operations necessary for executing a query and executes the query based on the query execution plan. In the execution of the query, the DBMS dynamically generates a task for executing a DB operation and executes the dynamically generated task. The DBMS executes a task in a plurality of threads executed by a processor core.

Database management system, computer, and database management method

When a DBMS receives a suspend instruction in which a suspend completion time of query processing is a future time and between receipt of the suspend instruction and the suspend completion time, if there is a target object (at least a processing object whose execution is in progress upon receipt of the suspend instruction) whose predicted completion time is at or precedes the suspend completion time, the DBMS changes the state of the target object to a state signifying a snapshot suspend. If there is a processing object whose state signifies a snapshot suspend, the DBMS executes the processing object at or before the suspend completion time.

Database management system and database management method

There is provided a database management system (DBMS) in order to make anonymization processing of the database efficient. When receiving a query including a conversion rule, the database management system is configured to process a relationship table in the database based on the conversion rule. At that time, the DBMS is configured to acquire data from a processing result table (result of processing the relationship table) stored in the past for tuples the number of which for each value appearing in a predetermined attribute satisfies a condition required for the anonymization processing. On the other hand, for tuples the number of which for each value appearing in a predetermined attribute does not satisfy the condition required for the anonymization processing, the DBMS is configured to acquire data from the database or from a result of processing the relationship table, the result being stored in rather than the processing result table.

Database management system and anonymization processing method

A database management system (DBMS) performs, in response to a conversion request to convert a store format of a table in a database, a process (base type change process) for changing a store format indicated by information (base type) indicating the store format of the table to a store format according to the conversion request, and performs a data conversion process asynchronously with the aforementioned process. In an import process after the base type change process, the DBMS imports, into the table, a chunk in the store format indicated by the base type after change. In the data conversion process, the DBMS converts a chunk in a store format different from the store format indicated by the base type into a chunk in the store format indicated by the base type.

If a query indicates joining of N (N is an integer of no less than 3) relation tables, a database management system calculates a query cost that is based on a power consumption amount for query execution, for each of a first query plan candidate in which a temporary table is generated and the temporary table is stored in a storage device unit with a first access cost, a second query plan candidate in which a temporary table is generated and the temporary table is stored in a storage device unit with a second access cost that is higher than the first access cost and a third query plan candidate in which the N relation tables are joined in a pipelined manner without generation of a temporary table, selects a relatively low-query cost query plan candidate and executes the query based on the query plan candidate.

Database management system and method

A second query execution part is added to a database management system comprising a first query execution part configured to execute a query based on a query execution plan of a query to a database and to return a query execution result to the query issuance source and a buffer management part configured to read a data of a read request from the database to store the data into the buffer and to provide the data to an issuance source of the read request if data of a read request has not been stored in a buffer in the case where the read request of data is received and configured to read data of a read request from the buffer and to provide the data to a issuance source of the read request if data of a read request has been stored in the buffer.

Database management system and computer system having first and second query execution parts which execute database operations in parallel

As an I/O method of issuing an I/O request, there are a synchronous I/O method, in which a task is in a waiting state until an I/O response to the I/O request is returned and an asynchronous I/O method, in which another task can be executed before an I/O response to the I/O request is returned. When issuing an I/O request in execution of a task, a DBMS selects any one of the synchronous I/O method and the asynchronous I/O method, based on an I/O response speed of an I/O destination storage device and issues an I/O request according to the selected I/O method.

Since storage devices are activated in the issuance order of I/O commands, the time required for processing of a plurality of I/O commands based on one or more I/O requests may become long. When issuance destinations of two or more I/O commands are two or more storage devices in a non-activated state from among a plurality of storage devices, a computer system determines an activation order of the two or more storage devices on the basis of two or more I/O quantities which respectively correspond to the two or more storage devices. Each of the I/O quantities of the two or more storage devices is an I/O quantity in accordance with one or more I/O commands for the relevant storage device from among the two or more I/O commands. The computer system activates the two or more storage devices in the determined activation order.

Computer system and storage device activation control method

A database management system (DBMS) manages a database existing in a second storage device with an access speed lower than that of a first storage device. In an execution of a query, the DBMS dynamically generates tasks two or more executable tasks in parallel. The DBMS generates task start information which is information representing a content of the execution of the task, manages the task start information, and executes a content represented by the task start information by the task. The task start information includes a data address set existing in the second storage device. The DBMS controls movement of the data address sets between the first storage device and the second storage device based on a management state of the task start information. In addition, the DBMS selects the task start information based on whether or not the data address set exists in the first storage device.

A computer system includes: a database server configured to execute a database management system; and a storage apparatus configured to store data. The storage apparatus is configured to have a power saving function for switching between a sleep mode for reducing power consumption of the storage apparatus and an active mode for enabling read and write of the data. The database management system is configured to be executed by the arithmetic device, to thereby: receive a query for reading or writing data; analyze the received query to create an execution plan; identify a volume for reading and writing data; and select an execution plan for which power consumption satisfies a predetermined threshold value based on power consumption information on the identified volume.

Computer system, method for conserving power, and computer

Provided is a database management apparatus, having a processor, a memory, and a storage device, whereby a database which is stored in the storage device is managed, the database management apparatus further comprising: a query acceptance unit which accepts a query to the database; a query execution plan generating unit which generates a query execution plan which includes a database operation which is necessary for executing the accepted query; and a query execution unit which, in executing the accepted query on the basis of the generated query execution plan, dynamically generates a task for executing the database operation, and executes the dynamically generated task. The query execution unit acquires a resource usage state, and, when executing the next database operation, generates a new task on the basis of the resource usage state, and executes the new task in parallel with the task.

Database management apparatus, database management method, and storage medium

The present invention relates to a technology for verifying relevance of data. One object of the present invention is to suppress increase in time required for verifying relevance of data. According to one embodiment of the present invention, a computer system includes: a storage apparatus configured to provide a storage area formed by storage devices; and a computer configured to manage data. The storage area is configured to store a plurality of pieces of data. The plurality of pieces of data include a first piece of data associated with a second piece of data. The computer is configured to: verify whether or not the first piece of data is normally associated with the second piece of data; and start, when the plurality of pieces of data are verified, verification for one piece of data irrespective of whether or not verification for another piece of data is complete.

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Tokyo, Japan

Kazuo Goda