What is InnoDB and MyISAM in MySQL?

InnoDB and MYISAM, are storage engines for MySQL.

These two differ on their locking implementation: InnoDB locks the particular row in the table, and MyISAM locks the entire MySQL table.

You can specify the type by giving MYISAM OR InnoDB while creating a table in DB.

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InnoDB and MyISAM

InnoDB is a storage engine for MySQL, included as standard in all current binaries distributed by MySQL AB. Its main enhancement over other storage engines available for use with MySQL is ACID-compliant transaction support

MyISAM is the default storage engine for the MySQL relational database management system versions prior to 5.5 1. It is based on the older ISAM code but has many useful extensions. The major deficiency of MyISAM is the absence of transactions support. Versions of MySQL 5.5 and greater have switched to the InnoDB engine to ensure referential integrity constraints, and higher concurrency.

They are storage engines.

http://dev.mysql.com/doc/refman/5.1/en/storage-engines.html

MyISAM: The default MySQL storage engine and the one that is used the most in Web, data warehousing, and other application environments. MyISAM is supported in all MySQL configurations, and is the default storage engine unless you have configured MySQL to use a different one by default.

InnoDB: A transaction-safe (ACID compliant) storage engine for MySQL that has commit, rollback, and crash-recovery capabilities to protect user data. InnoDB row-level locking (without escalation to coarser granularity locks) and Oracle-style consistent nonlocking reads increase multi-user concurrency and performance. InnoDB stores user data in clustered indexes to reduce I/O for common queries based on primary keys. To maintain data integrity, InnoDB also supports FOREIGN KEY referential-integrity constraints.