Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A database management system generates an execution plan by performing the following (A) and (B): (A) processing of dividing a provisional execution plan that is an access path into one or more query processing blocks that are each a simultaneously executable processing range, the access path being specified on the basis of a received query and indicating an execution order of database operation; and (B) processing of determining, for each of the one or more query processing blocks, whether an execution cost decreases by changing an inner configuration of the query processing block on the basis of at least one of a processing time, performance, and the number of storage devices for one or more processing in the query processing block, and changing the inner configuration of the query processing block when a determination result is true.

Abstract: 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.

Abstract: 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.