What Are the Core Components of MySQL? A Deep Dive

MySQL consists of five main components: connector, parser, optimizer, executor, and storage engine.

Connector

The connector establishes a connection to the MySQL server, authenticates the user, and manages the session.

mysql -h $ip -u root -p

Query Cache

After connecting, MySQL checks the query cache to see if the same SELECT statement has been executed before; if found, the result is returned directly. This module was removed in MySQL 8.0.

Parser

The parser performs lexical and syntactic analysis of the SQL statement, identifying tokens and checking for syntax errors.

Optimizer

Based on the table structure and query intent, the optimizer generates an execution plan and chooses appropriate indexes.

Executor

The executor carries out the plan by invoking the storage engine to read or write data and returns the result to the client. select * from users where name = 'operator' If the users table lacks an index on the name column, the executor repeatedly scans rows via the InnoDB engine, evaluating each row until the matching one is found, then returns the result set.