MySQL 5.5 Release Notes
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InnoDB is a general-purpose storage engine that
balances high reliability and high performance. Starting from MySQL
5.5.5, the default storage engine for new tables is
InnoDB rather than
MyISAM. Unless you have configured a
different default storage engine, issuing a
CREATE TABLE statement without an
ENGINE= clause creates an
InnoDB table. Given this change of default
behavior, MySQL 5.5 might be a logical point to evaluate whether
tables that use MyISAM could benefit from
switching to InnoDB.
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 14.5, “InnoDB and the ACID Model” for more information.
Row-level locking and Oracle-style consistent reads increase multi-user concurrency and performance. See Section 14.8, “InnoDB Locking and Transaction Model” for more information.
InnoDBtables arrange your data on disk to optimize queries based on primary keys. EachInnoDBtable has a primary key index called the clustered index that organizes the data to minimize I/O for primary key lookups. See Section 14.11.9, “Clustered and Secondary Indexes” for more information.To maintain data integrity,
InnoDBsupportsFOREIGN KEYconstraints. With foreign keys, inserts, updates, and deletes are checked to ensure they do not result in inconsistencies across different tables. See Section 14.11.7, “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
The InnoDB storage engine in MySQL
5.5 releases includes a number performance improvements
that in MySQL 5.1 were only available by installing the
InnoDB Plugin. This latest
InnoDB offers new features, improved performance
and scalability, enhanced reliability and new capabilities for
flexibility and ease of use.
For information about InnoDB enhancements and new
features in MySQL 5.5, refer to:
The
InnoDBenhancements list in Section 1.4, “What Is New in MySQL 5.5”.The Release Notes.
Additional InnoDB Information and Resources
For
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/.