Search apparatus, storage medium, database system, and search method

A non-transitory computer-readable storage medium storing a computer program:

• receive a query for searching for top N (N is a natural number) cases of data among cases of data that are targets;
• acquire n cases of data (n is a natural number equal to or smaller than N) from each of a plurality of nodes distributively holding the cases of data that are targets on the basis of the received query;
• decide whether or not the top N cases of data can be settled from the n acquired cases of data;
• and
• determine a node from which data will be acquired next time from among the plurality of nodes and the number of cases of data to be acquired when it is decided that the top N cases of data cannot be settled.

A database system comprising a search apparatus and a plurality of nodes,

• wherein the search apparatus includes
• a query reception device that receives a query for searching for top N (N is a natural number) cases of data among cases of data that are targets;
• a data acquisition device that acquires n cases of data (n is a natural number equal to or smaller than N) from each of a plurality of nodes distributively holding the cases of data that are targets on the basis of the query received by the query reception device;
• a decision device that decides whether or not the top N cases of data can be settled from the n cases of data acquired by the data acquisition device;
• and
• a determination device that determines a node from which data will be acquired next time from among the plurality of nodes and the number of cases of data to be acquired when the decision device decides that the top N cases of data cannot be settled, and
• the node includes
• a storage device that stores the cases of data that are targets;
• and
• a query execution device that executes the query received from the search apparatus to acquire n cases of data from the cases of data that are targets stored in the storage device, and transmits the acquired data to the search apparatus.

A search method comprising:

• receiving, by a computer of a search apparatus, a query for searching for top N (N is a natural number) cases of data among cases of data that are targets;
• acquiring, by the computer, n cases of data (n is a natural number equal to or smaller than N) from each of a plurality of nodes distributively holding the cases of data that are targets on the basis of the received query;
• deciding, by the computer, whether or not the top N cases of data can be settled from the n acquired cases of data;
• and
• determining, by the computer, a node from which data will be acquired next time from among the plurality of nodes and the number of cases of data to be acquired when it is decided that the top N cases of data cannot be settled.