Method and device for applying filtration factor assessment in optimization of access path in database

Abstract

The invention provides a method and a device for applying filtering factor assessment in optimization of an access path in a database. The method for applying the filtering factor assessment in the optimization of the access path in the database comprises extracting a relevance condition from statement sections used for database inquiry, wherein the relevance condition defines a relationship between a variable and a first table; obtaining first statistical information according to the relevance condition and statistical information of the first table; extracting a filtering condition from the statement sections, wherein the filtering condition defines a relationship between the variable and a second table; obtaining second statistical information according to the filtering condition and statistical information of the second table; and assessing a filtering factor of the filtering condition according to the first statistical information and the second statistical information. The device for applying the filtering factor assessment in the optimization of the access path in the database corresponds to the method for applying the filtering factor assessment in the optimization of the access path in the database. The method and the device for applying the filtering factor assessment in the optimization of the access path in the database are capable of accurately assessing the filtering factor of the filtering condition, and thus are beneficial for carrying out the further optimization of the access path.

Description

technical field [0001] The present invention relates to the optimization of the access path of the database, more specifically, to the method and device for evaluating the filter factor to optimize the access path in the database. Background technique [0002] In the process of accessing and retrieving in the database, in order to execute the query, the database needs to create an access plan (access plan). An access plan defines in what order tables are accessed, which indexes are used, and which join method is used to associate data. A good access plan is crucial for fast execution of SQL statements. Most RDBMS (Relational Database Management System, relational database management system) use cost-based optimizer to create access plan. The basic cost optimizer evaluates the cost of each alternative access path according to the statistical information in the database, and selects the access path with the lowest cost as the optimal path. The above-mentioned costs mainly i...

AI Technical Summary

Problems solved by technology

However, the overhead of performing re-optimization during runtime is sometimes unacceptable or affects program execution performance

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