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MySQL Storage Engines
What is a Storage Engine?
October 7, 2005
Data in MySQL is stored in files (or memory) using a variety of different techniques. Each of these techniques employ different storage mechanisms, indexing facilities, locking levels and ultimately provide a range of different functions and capabilities. By choosing a different technique you can gain additional speed or functionality benefits that will improve the overall functionality of your application.
For example, if you work with a large amount of temporary data, you may want to make use of the MEMORY storage engine, which stores all of the table data in memory. Alternatively, you may want a database that supports transactions (to ensure data resilience).
Each of these different techniques and suites of functionality within the MySQL system is referred to as a storage engine (also known as a table type). By default, MySQL comes with a number of different storage engines pre-configured and enabled in the MySQL server. You can select the storage engine to use on a server, database and even table basis, providing you with the maximum amount of flexibility when it comes to choosing how your information is stored, how it is indexed and what combination of performance and functionality you want to use with your data.
This flexibility to choose how your data is stored and indexed is a major reason why MySQL is so popular; other database systems, including most of the commercial options, support only a single type of database storage. Unfortunately the 'one size fits all approach' in these other solutions means that either you sacrifice performance for functionality, or have to spend hours or even days finely tuning your database. With MySQL, we can just change the engine we are using.
In this article, we're not going to concentrate on the technical aspects of the different storage engines (although we will inevitably have to look at some of these elements), instead we will concentrate on how and where these different engines can be best employed. To achieve this, we'll have to look at some of the fundamental issues before moving on to the specifics of each engine type.