Table of Contents [+/-]
- 14.1 Comparing Transaction and Nontransaction Engines
- 14.2 Other Storage Engines
- 14.3 Setting the Storage Engine
- 14.4 Overview of MySQL Storage Engine Architecture [+/-]
- 14.5 The MyISAM Storage Engine [+/-]
- 14.6 The InnoDB Storage Engine [+/-]
- 14.7 The IBMDB2I Storage Engine [+/-]
- 14.8 The MERGE Storage Engine [+/-]
- 14.9 The MEMORY Storage Engine
- 14.10 The EXAMPLE Storage Engine
- 14.11 The FEDERATED Storage Engine [+/-]
- 14.12 The ARCHIVE Storage Engine
- 14.13 The CSV Storage Engine [+/-]
- 14.14 The BLACKHOLE Storage Engine
MySQL supports several storage engines that act as handlers for different table types. MySQL storage engines include both those that handle transaction-safe tables and those that handle nontransaction-safe tables.
As of MySQL 5.1, MySQL Server uses a pluggable storage engine architecture that enables storage engines to be loaded into and unloaded from a running MySQL server.
Prior to MySQL 5.1.38, the pluggable storage engine architecture is supported on Unix platforms only and pluggable storage engines are not supported on Windows.
To determine which storage engines your server supports by using the
SHOW ENGINES statement. The value in
Support column indicates whether an engine
can be used. A value of
DEFAULT indicates that
an engine is available, not available, or available and currently
set as the default storage engine.
SHOW ENGINES\G*************************** 1. row *************************** Engine: FEDERATED Support: NO Comment: Federated MySQL storage engine Transactions: NULL XA: NULL Savepoints: NULL *************************** 2. row *************************** Engine: MRG_MYISAM Support: YES Comment: Collection of identical MyISAM tables Transactions: NO XA: NO Savepoints: NO *************************** 3. row *************************** Engine: MyISAM Support: DEFAULT Comment: Default engine as of MySQL 3.23 with great performance Transactions: NO XA: NO Savepoints: NO ...
This chapter describes each of the MySQL storage engines except for
NDBCLUSTER, which is covered in
Chapter 17, MySQL Cluster NDB 6.1 - 7.1. It also contains a description of
the pluggable storage engine architecture (see
Section 14.4, “Overview of MySQL Storage Engine Architecture”).
For information about storage engine support offered in commercial MySQL Server binaries, see MySQL Enterprise Server 5.1, on the MySQL Web site. The storage engines available might depend on which edition of Enterprise Server you are using.
For answers to some commonly asked questions about MySQL storage engines, see Section A.2, “MySQL 5.1 FAQ: Storage Engines”.
MySQL 5.1 supported storage engines
MyISAM: The default MySQL storage engine and the one that is used the most in Web, data warehousing, and other application environments.
MyISAMis 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.
InnoDBrow-level locking (without escalation to coarser granularity locks) and Oracle-style consistent nonlocking reads increase multi-user concurrency and performance.
InnoDBstores user data in clustered indexes to reduce I/O for common queries based on primary keys. To maintain data integrity,
FOREIGN KEYreferential-integrity constraints.
Memory: Stores all data in RAM for extremely fast access in environments that require quick lookups of reference and other like data. This engine was formerly known as the
Merge: Enables a MySQL DBA or developer to logically group a series of identical
MyISAMtables and reference them as one object. Good for VLDB environments such as data warehousing.
Archive: Provides the perfect solution for storing and retrieving large amounts of seldom-referenced historical, archived, or security audit information.
Federated: Offers the ability to link separate MySQL servers to create one logical database from many physical servers. Very good for distributed or data mart environments.
NDBstorage engine is not supported in standard MySQL 5.1 releases. Currently supported MySQL Cluster releases include MySQL Cluster NDB 7.0 and MySQL Cluster NDB 7.1, which are based on MySQL 5.1, and MySQL Cluster NDB 7.2, which is based on MySQL 5.5. While based on MySQL Server, these releases also contain support for
CSV: The CSV storage engine stores data in text files using comma-separated values format. You can use the CSV engine to easily exchange data between other software and applications that can import and export in CSV format.
Blackhole: The Blackhole storage engine accepts but does not store data and retrievals always return an empty set. The functionality can be used in distributed database design where data is automatically replicated, but not stored locally.
Example: The Example storage engine is “stub” engine that does nothing. You can create tables with this engine, but no data can be stored in them or retrieved from them. The purpose of this engine is to serve as an example in the MySQL source code that illustrates how to begin writing new storage engines. As such, it is primarily of interest to developers.
It is important to remember that you are not restricted to using the same storage engine for an entire server or schema: you can use a different storage engine for each table in your schema.
Choosing a Storage Engine
The various storage engines provided with MySQL are designed with different use cases in mind. To use the pluggable storage architecture effectively, it is good to have an idea of the advantages and disadvantages of the various storage engines. The following table provides an overview of some storage engines provided with MySQL:
Table 14.1 Storage Engine Features
|Geospatial data type support||Yes||No||Yes||Yes||Yes|
|Geospatial indexing support||Yes||No||Yes[a]||No||No|
|Full-text search indexes||Yes||No||Yes[c]||No||No|
|Cluster database support||No||No||No||No||Yes|
|Foreign key support||No||No||Yes||No||No|
|Backup / point-in-time recovery[h]||Yes||Yes||Yes||Yes||Yes|
|Query cache support||Yes||Yes||Yes||Yes||Yes|
|Update statistics for data dictionary||Yes||Yes||Yes||Yes||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 MyISAM tables are supported only when using the compressed row format. Tables using the compressed row format with MyISAM are read only.
[e] Compressed InnoDB tables require the InnoDB Barracuda file format.
[f] Implemented in the server (via encryption functions), rather than in the storage engine.
[g] Implemented in the server, rather than in the storage engine.
[h] Implemented in the server, rather than in the storage engine.