14.1 Introduction to InnoDB

14.1 Introduction to InnoDB
Previous	Chapter 14 The InnoDB Storage Engine	Next

14.1.1 Benefits of Using InnoDB Tables
14.1.2 Best Practices for InnoDB Tables
14.1.3 Checking InnoDB Availability
14.1.4 Testing and Benchmarking with InnoDB
14.1.5 Turning Off InnoDB

InnoDB is a general-purpose storage engine that balances high reliability and high performance. In MySQL 5.6, InnoDB is the default MySQL storage engine. Unless you have configured a different default storage engine, issuing a CREATE TABLE statement without an ENGINE= clause creates an InnoDB table.

InnoDB includes all the features that were part of the InnoDB Plugin for MySQL 5.1, plus new features specific to MySQL 5.5 and higher.

Note

The mysql and INFORMATION_SCHEMA databases that implement some of the MySQL internals still use MyISAM. In particular, you cannot switch the grant tables to use InnoDB.

Key Advantages of InnoDB

Key advantages of InnoDB include:

Its DML operations follow the ACID model, with transactions featuring commit, rollback, and crash-recovery capabilities to protect user data. See Section 14.2, “InnoDB and the ACID Model” for more information.
Row-level locking and Oracle-style consistent reads increase multi-user concurrency and performance. See Section 14.5, “InnoDB Locking and Transaction Model” for more information.
InnoDB tables arrange your data on disk to optimize queries based on primary keys. Each InnoDB table has a primary key index called the clustered index that organizes the data to minimize I/O for primary key lookups. See Section 14.8.9, “Clustered and Secondary Indexes” for more information.
To maintain data integrity, InnoDB supports FOREIGN KEY constraints. With foreign keys, inserts, updates, and deletes are checked to ensure they do not result in inconsistencies across different tables. See Section 14.8.7, “InnoDB and FOREIGN KEY Constraints” for more information.

Table 14.1 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 15, Alternative Storage Engines.

InnoDB Enhancements and New Features

For information about InnoDB enhancements and new features in MySQL 5.6, refer to:

The InnoDB enhancements list in Section 1.4, “What Is New in MySQL 5.6”.
The Release Notes.

Additional InnoDB Information and Resources

For InnoDB-related terms and definitions, see MySQL Glossary.
For a forum dedicated to the InnoDB storage engine, see MySQL Forums::InnoDB.
InnoDB is 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/.