Mastering MariaDB

Chapter 3. Optimizing Queries

This chapter explains the basics of how to improve the performance of the queries that are executed on a MariaDB server. First, the important tools required to find slow queries are described. Once we find such queries, we will need to find out why they are slow. Thus, a description of how MariaDB uses indexes follows. Then, we will discuss the EXPLAIN command, which shows how MariaDB executes a query. Contextually, we will also discuss the main execution strategy.

The topics covered in this chapter are:

• The slow query log
• The pt-query-digest command from Percona Toolkit
• Indexes
• Table statistics
• The EXPLAIN statement
• Important MariaDB optimizations

The slow query log

The slow query log (or simply slow log) stores SQL statements ...