Database query optimization method and system

Abstract

The invention discloses a database query optimization method. The database query optimization method comprises a connection sequence selector and a self-adaptive decision network, wherein the connection sequence selector is used for selecting an optimal connection sequence in the query plan and comprises a new database query plan coding scheme, and codes are in one-to-one correspondence with the connection sequence; a value network which is used for predicting the execution time of the query plan, is trained by the query plan and the corresponding real execution time, and is used for reward feedback in Monte Carlo tree search; a Monte Carlo tree search method which is used for simulating and generating multiple different connection sequences, evaluating the quality of the connection sequences through a connection sequence value network, and returning a recommended connection sequence after preset exploration times are reached. And the adaptive decision network is used for distinguishing whether the query statement uses the connection sequence selector or not, so that the overall performance of the optimization system is improved. According to the method and the system, the limitation of a traditional query optimizer can be effectively avoided, and the database query efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of databases, and more specifically relates to a database query optimization method and system. Background technique [0002] With the rapid development of Internet technology, databases are playing an increasingly important role as a traditional means of supporting data storage and query. Facing the huge amount of data in the database, the efficiency of data retrieval has become one of the important issues that researchers are concerned about. Usually, a relational database optimizes the input query statement through a query optimizer, and the query optimizer is a key component for a database system to obtain good performance. [0003] The SQL statement executed by the database is a declarative language, which only declares what kind of results the user wants, and does not care about how the physical execution engine of the database obtains and returns data. The main job of the query optimizer is to optim...

AI Technical Summary

Problems solved by technology

Its purpose is to solve the technical problems of the existing database query optimizer due to the complexity of the database system, the skew and correlation between data, and the cost model is based on a large number of assumptions, resulting in inaccurate cost estimation results, and due to the use of a large number of heuristics The technical problem of missing the query plan with shorter execution time and low query efficiency due to the reduction of enumeration space by the formula strategy

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