Database processing system and method

A computer which outputs all query results in response to query requests received from outside, the computer comprising:

• a first interface coupled via a network to a storage system which stores data to be output in accordance with the query requests;
• a processor coupled to the first interface;
• and
• a memory coupled to the processor,
• wherein the storage system comprises a second interface, which is coupled to the computer, a control unit, which is coupled to the second interface, and storage, which is coupled to the control unit,
• wherein the storage stores data and storage location information in which storage locations of the data are recorded in a given order,
• wherein the processor is configured to:
• receive query requests for outputting query results in an order of values recorded in the storage location information;
• create sort trigger information indicating order relations that are specified in the query requests, based on the storage location information;
• send the plurality of data input requests to the storage system via the first interface;
• receive, from the storage system via the first interface, data that is fetched from among the data stored in the storage system in accordance with each of the plurality of data input requests which are received from the computer;
• store a query result in association with the sort trigger information in the memory;
• determine, before all of the plurality of data input requests sent are fulfilled, from the trigger information whether or not a query result to be output next is found in already fetched partial data stored in the memory, which is only part of the pieces of data to be fetched by the storage system;
• and
• start, in the case where the data to be output next is found, outputting the query result,
• wherein the sort trigger information is structured such that values hierarchized based on precedence relations of operations in the query plan and corresponding to an access order in which one of the data and the storage location information is accessed are linked together, the values linking one hierarchy level to another,
• wherein the memory includes a temporary buffer, which temporarily holds query results generated from the data that is fetched from the storage system in accordance with the query requests,
• wherein the memory stores task management information for managing a task that is being executed by the processor, and
• wherein the processor is configured to:
• select, in the case where capacity of data stored in the temporary buffer exceeds a given threshold, from the task management information, a task that holds sort trigger information to be output before sort trigger information that is held in the temporary buffer;
• and
• reissue data input requests that have been issued in the selected task, at a higher priority level than a priority level of data input requests that are output in other tasks.

A database processing method for a system having a computer, which outputs all query results in response to query requests received from outside, and a storage system, which stores data to be output in accordance with the query requests, the database processing method including the steps of:

• receiving, by the computer, query requests for outputting query results in an order of values recorded in storage location information in which storage locations of the data are recorded in a given order;
• creating, by the computer, sort trigger information indicating order relations that are specified in the query requests, based on the storage location information;
• sending, by the computer, the plurality of data input requests to the storage system;
• sending, by the storage system, for each of the plurality of data input requests received from the computer, data that is fetched in accordance with the received plurality of data input request to the computer;
• storing, by the computer, a query result in association with the sort trigger information in a memory;
• determining, by the computer, before all of the plurality of data input requests sent are fulfilled, from the sort trigger information whether or not a query result to be output next is found in already fetched partial data stored in the memory, which is only part of the pieces of data to be fetched by the storage system;
• and
• starting, by the computer, in the case where the data to be output next is found, outputting the query result,
• wherein the sort trigger information is structured such that values hierarchized based on precedence relations of operations in the query plan and corresponding to an access order in which one of the data and the storage location information is accessed are linked together, the values linking one hierarchy level to another,
• wherein the memory includes a temporary buffer, which temporarily holds query results generated from the data that is fetched from the storage system in accordance with the query requests, and
• wherein, in the case where capacity of data stored in the temporary buffer exceeds a first given threshold, the computer is configured to sort the received query results by using a temporary storage space which is allocated to external storage accessible to the computer.