MyISAM

MyISAM

Developer(s)	Oracle Corporation
Operating system	Cross-platform
Type	Database engine
License	GNU General Public License
Website	mysql.com

MyISAM was 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.

Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. MySQL uses a .frm file to store the definition of the table, but this file is not a part of the MyISAM engine; instead it is a part of the server. The data file has a .MYD (MYData) extension. The index file has a .MYI (MYIndex) extension.

See also

• Comparison of MySQL database engines

Notes

1. ^ http://dev.mysql.com/doc/refman/5.5/en/innodb.html

External links

• MySQL Documentation on MyISAM Storage Engine
• MyISAM's open files limit and table-cache problem explained
• The article about problems which will occur in using MyISAM