Database management system, computer, and database management method

摘要

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 in accordance with the query execution plan. In the execution of the query, the DBMS dynamically generates tasks for executing the DB operations and executes the dynamically generated tasks. The query execution plan includes a plurality of query blocks, which are sets of one or more DB operations. When newly generating a task, the DBMS executes determination processing of simultaneous-task-generation number. The determination processing of simultaneous-task-generation number is to calculate, targeting each of the query blocks, the number of simultaneous task generation, which is the number of tasks simultaneously generatable as tasks for executing the query block. The number of the dynamically generated tasks is equal to or smaller than the number of simultaneous task generation.

主权项

1. A database management system for managing a database, the database management system comprising:
a processor; and a memory connected to the processor, the memory storing instructions that, when executed by the processor, cause the processor to: receive a query to the database; generate a query execution plan including information representing one or more database operations necessary for executing the received query, and the generated query execution plan includes a plurality of query blocks, which are sets of one or more of the database operations necessary for executing the received query; and execute the received query in accordance with the generated query execution plan and, in the execution of the received query, dynamically generate a plurality of tasks for executing the database operations and execute the dynamically generated tasks, wherein the execution of the received query includes to execute determination processing of a plurality of task-generation numbers when newly generating the tasks in the execution of the received query, wherein the determination processing of the task-generation numbers includes to calculate, targeting each of the plurality of query blocks, the task-generation numbers which indicate a number of dynamically generated tasks that can be generated as the tasks for executing the target query block, wherein the number of the dynamically generated tasks is equal to or smaller than the task-generation number for the target query block, and wherein the task-generation numbers are calculated based on a ratio of each of a plurality of memory resource amounts required for the execution of each of the plurality of query blocks to an upper limit of a memory resource amount allocatable to the execution of the received query.