In this chapter, we reviewed the general MariaDB architecture. Many features of the mysql client were explained. They increase productivity of the DBA and reduce the need for a GUI.

We discussed the storage engines that are included in MariaDB's binaries or sources. An overview of InnoDB, TokuDB, MyISAM, and Aria was presented. InnoDB will be used in this book and in most practical cases. For this reason, special attention has been dedicated to this engine and its data structures. However, uncommon use cases could benefit from other engines, for one reason or another. Also, a brief description of all the minor storage engines was presented. These engines can be used to solve specific problems. For example, Spider will be discussed in a later chapter, while the chapter about replication will show how BLACKHOLE can be used to avoid replicating some data.

The logs used by the server were briefly introduced. Some of them are essential to use some MariaDB features, such as physical backups, replication, or recovering after a DELETE statement that erased too much data. The details about how to use, configure, and maintain the logs will be explained in the later chapters, when the logs will be used for practical purposes.

The most important concepts about caches and security were reviewed. More details will be discussed in the chapters entirely dedicated to these topics.

The INFORMATION_SCHEMA and PERFORMANCE_SCHEMA databases contain a lot of useful information. This book does not explain all the tables in detail, because exhaustive information about them can be found in the MariaDB's KB. However, in the later chapters, some of these tables will be explained and used to demonstrate how they can be of help for practical purposes.

Since MariaDB is a fork of MySQL, the compatibility between different versions of MariaDB and MySQL was discussed. This topic is important while gradually replacing MySQL servers with MariaDB, while using a replication environment where MariaDB and MySQL coexist, or while developing an application that must work with both the DBMS (particularly if the developers want to take advantage of MariaDB's unique features).

Finally, this chapter presents a list of the most useful MariaDB resources. All advanced users should check them regularly to keep themselves updated with new releases and never stop learning!

In the next chapter, we will learn how to use some logs to find the errors that occurred in MariaDB, and how to debug SQL statements. This information is important for troubleshooting, and we will use it to deal with the more complex topics that will be discussed in the following chapters.