Database management system and method for query process for the same

Abstract

A database management system for executing database operations in parallel by a plurality of nodes and a query processing method for it are described. The database management system contains a decision management node for deciding a distribution node for retrieving information so as to analyze a query received from an application program, generate a processing procedure for processing the query, and execute the process and a join node for sorting, merging, and joining the information retrieved by the distribution node. When the query process is executed, the distribution node decided by the decision management node retrieves the information to be processed and the join node decided by the decision management node also obtains the result for the query from the retrieved information. The query result is outputted from an output node and transferred to the application program.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a database management system and more particularly to a database processing method which is suitable for parallel query process suited to a relational database management system. [0002] A database management system (hereinafter abbreviated to DBMS), particularly a relational DBMS processes a query which is represented in a non-procedural database language, decides the internal processing procedure, and executes the query process according to this internal processing procedure. As a database language, a database language which is regulated in Database Language SQL ISO 9075:1989 and called SQL is widely used. Among main conventional query processing methods, there are a method for deciding a single internal processing procedure on the basis of the predefined rule and a method for deciding an optimum procedure from a plurality of candidate processing procedures which are selected using various statistical information a...

AI Technical Summary

Benefits of technology

[0007] An object of the present invention is to eliminate the aforementioned difficulties in a conventional parallel database system and to provide a database management system and a database processing method for realizing a quicker query process.

[0012] According to the query processing method of the present invention, the number of nodes can be decided in correspondence with the database operation which is executed in each node. When there is a scattering in distribution of data, the data is equally distributed to each node, and each database operation to be executed in each node is parameterized, and the expected processing times are equalized. Therefore, the processing time in each node is not biased and the pipeline operation can be performed smoothly.

Problems solved by technology

In the case of the former, the load for generating the processing procedure is small, though there is a problem imposed in the propriety of the rules which are set uniformly and there is also a problem imposed in the optimization of the selected internal processing procedure.

Therefore, there is a problem imposed that a processing procedure which is obtained by the query analysis process beforehand is not always optimum.

However, when the parallelism is excessively increased, problems such as an increase in the overhead or an increase in the response time of transactions may be imposed.

Therefore, it is difficult to obtain an appropriate parallelism and to realize an optimum load distribution.

If there is a scattering in the data amount stored in each node when performing database operations in the manner of the pipeline operation, the processing time in each node is biased and the pipeline operation cannot be performed smoothly.

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