Author: Zen and the Art of Computer Programming
1 Introduction
A database is an infrastructure that manages massive amounts of data and plays an important role in application development. The application needs to read data from the database, save data, update data and other operations, and monitor the running status of the database system. If a database system has performance problems, it becomes critical to troubleshoot the problem and optimize the database system.
The SQL performance analysis tool EXPLAIN (Explain) can be used to analyze query statements or execution plans and give detailed execution information. Viewing the detailed information of the execution plan through EXPLAIN can help developers better understand the execution process of query statements, identify possible problems, and perform targeted optimization.
This article will first give a comprehensive introduction to the SQL performance analysis tool EXPLAIN, including its functions, uses and principles. Then introduce a series of indicators in the EXPLAIN output results, and explain the meaning and function of each indicator in detail.
Finally, we will combine specific cases and share some of the knowledge and skills behind EXPLAIN through practical examples. We also hope that readers can communicate with the authors and make progress together.
2. Functions of SQL performance analysis tool EXPLAIN
2.1 SQL performance analysis
SQL performance analysis is a tool-based performance tuning method used to analyze SQL execution efficiency issues. Generally speaking, the goal of SQL performance analysis is to find factors that affect SQL performance, such as indexes, locks, connections, data types, hardware configurations, etc., and to adjust the corresponding settings accordingly.
EXPLAIN is a SQL performance analysis tool that can be used to analyze execution plans and give the difference between the query parser, the execution plan generated by the query optimizer, and the actual execution plan of the server, providing a more accurate analysis of SQL execution efficiency.
2.2 SQL optimization suggestions
After using EXPLAIN to analyze the query statement,