Storage engines in MySQL

MySQL supports several storage engines that act as handlers for different table types. The server, and in fact the developer, can choose how and where a database table is to be stored based on which storage engine is best suited for a particular situation.

There are mainly four storage engines, each with different characteristics:

* MyISAM is a disk based storage engine. Aiming for very low overhead, it does not support transactions.

* InnoDB is also disk based, but offers versioned, fully ACID transactional capabilities. InnoDB requires more disk space than MyISAM to store its data, and this increased overhead is compensated by more aggressive use of memory caching, in order to attain high speeds.

* Memory (formerly called "HEAP") is a storage engine that utilizes only RAM. Special algorithms are used that make optimal use of this environment. It is very fast.

* NDB, the MySQL Cluster Storage engine, connects to a cluster of nodes, offering high availability through redundancy, high performance through fragmentation (partitioning) of data across multiple node groups, and excellent scalability through the combination of these two. NDB uses main-memory only, with logging to disk.

Every storage engine is completely different, designed to address a unique application need. Not being locked down to a single storage engine, means you can optimize and choose the best tool for the job.




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