InnoDB is a general-purpose storage engine that
balances high reliability and high performance. In MySQL
InnoDB is the default MySQL
storage engine. Unless you have configured a different default
storage engine, issuing a
TABLE statement without an
clause creates an
Key advantages of
Its DML operations follow the ACID model, with transactions featuring commit, rollback, and crash-recovery capabilities to protect user data. See Section 15.2, “InnoDB and the ACID Model” for more information.
Row-level locking and Oracle-style consistent reads increase multi-user concurrency and performance. See Section 15.5, “InnoDB Locking and Transaction Model” for more information.
InnoDBtables arrange your data on disk to optimize queries based on primary keys. Each
InnoDBtable has a primary key index called the clustered index that organizes the data to minimize I/O for primary key lookups. See Section 15.8.9, “Clustered and Secondary Indexes” for more information.
To maintain data integrity,
FOREIGN KEYconstraints. With foreign keys, inserts, updates, and deletes are checked to ensure they do not result in inconsistencies across different tables. See Section 15.8.7, “InnoDB and FOREIGN KEY Constraints” for more information.
Table 15.1 InnoDB Storage Engine Features
|Storage limits||64TB||Transactions||Yes||Locking granularity||Row|
|MVCC||Yes||Geospatial data type support||Yes||Geospatial indexing support||Yes[a]|
|B-tree indexes||Yes||T-tree indexes||No||Hash indexes||No[b]|
|Full-text search indexes||Yes[c]||Clustered indexes||Yes||Data caches||Yes|
|Index caches||Yes||Compressed data||Yes[d]||Encrypted data[e]||Yes|
|Cluster database support||No||Replication support[f]||Yes||Foreign key support||Yes|
|Backup / point-in-time recovery[g]||Yes||Query cache support||Yes||Update statistics for data dictionary||Yes|
[a] InnoDB support for geospatial indexing is available in MySQL 5.7.5 and higher.
[b] InnoDB utilizes hash indexes internally for its Adaptive Hash Index feature.
[c] InnoDB support for FULLTEXT indexes is available in MySQL 5.6.4 and higher.
[d] Compressed InnoDB tables require the InnoDB Barracuda file format.
[e] Implemented in the server (via encryption functions). Data-at-rest tablespace encryption is available in MySQL 5.7 and higher.
[f] Implemented in the server, rather than in the storage engine.
[g] Implemented in the server, rather than in the storage engine.
To compare the features of
InnoDB with other
storage engines provided with MySQL, see the Storage
Engine Features table in
Chapter 16, Alternative Storage Engines.
For information about
InnoDB enhancements and new
features in MySQL 5.7, refer to:
InnoDB-related terms and definitions, see MySQL Glossary.
For a forum dedicated to the
InnoDBstorage engine, see MySQL Forums::InnoDB.
InnoDBis published under the same GNU GPL License Version 2 (of June 1991) as MySQL. For more information on MySQL licensing, see http://www.mysql.com/company/legal/licensing/.