Table of Contents
InnoDBConcepts and Architecture
InnoDBPerformance Tuning and Troubleshooting
InnoDBFeatures for Flexibility, Ease of Use andReliability
InnoDBStartup Options and System Variables
Storage engines are MySQL components that handle the SQL operations for different table types.
InnoDB is the most general-purpose storage engine, and Oracle recommends using it
for tables except for specialized use cases. (The
TABLE statement in MySQL 5.7 creates
InnoDB tables by default.)
MySQL Server uses a pluggable storage engine architecture that enables storage engines to be loaded into and unloaded from a running MySQL server.
To determine which storage engines your server supports, use the
SHOW ENGINES statement. The value in the
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.
This chapter primarily describes the features and performance characteristics of
InnoDB tables. It also covers the use cases for the special-purpose MySQL storage
engines, except for
NDBCLUSTER which is covered in
For information about storage engine support offered in commercial MySQL Server binaries, see
For answers to some commonly asked questions about MySQL storage engines, see Section B.2, "MySQL 5.7 FAQ: Storage Engines".
A transaction-safe (ACID compliant) storage engine for MySQL that has commit, rollback, and
crash-recovery capabilities to protect user data.
InnoDB row-level locking
(without escalation to coarser granularity locks) and Oracle-style consistent nonlocking reads increase
multi-user concurrency and performance.
InnoDB stores user data in
clustered indexes to reduce I/O for common queries based on primary keys. To maintain data integrity,
InnoDB also supports
InnoDB is the default storage engine in
These tables have a small footprint. Table-level locking limits the
performance in read/write workloads, so it is often used in read-only or read-mostly workloads in Web
and data warehousing configurations.
Stores all data in RAM, for fast access in environments that require quick lookups of non-critical data.
This engine was formerly known as the
HEAP engine. Its use cases are
InnoDB with its buffer pool memory area provides a
general-purpose and durable way to keep most or all data in memory, and
NDBCLUSTER provides fast key-value lookups for huge distributed data
tables are really text files with comma-separated values. CSV tables let you import or dump data in CSV
format, to exchange data with scripts and applications that read and write that same format. Because CSV
tables are not indexed, you typically keep the data in
InnoDB tables during
normal operation, and only use CSV tables during the import or export stage.
These compact, unindexed tables are intended for storing and retrieving large amounts of
seldom-referenced historical, archived, or security audit information.
The Blackhole storage engine accepts but does not store data, similar to the Unix
device. Queries always return an empty set. These tables can be used in replication configurations where
DML statements are sent to slave servers, but the master server does not keep its own copy of the data.
Enables a MySQL DBA or developer to logically group a series of identical
MyISAM tables and reference them as one object. Good for VLDB
environments such as data warehousing.
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.
Example: This engine serves as an example in the MySQL source code that
illustrates how to begin writing new storage engines. It is primarily of interest to developers. The
storage engine is a "stub" that does nothing. You
can create tables with this engine, but no data can be stored in them or retrieved from them.
You are not restricted to using the same storage engine for an entire server or schema. You can specify the
storage engine for any table. For example, an application might use mostly
tables, with one
CSV table for exporting data to a spreadsheet and a few
MEMORY tables for temporary workspaces.
Choosing a Storage Engine
The various storage engines provided with MySQL are designed with different use cases in mind. The following table provides an overview of some storage engines provided with MySQL:
Table 14.1. Storage Engines Feature Summary
|Geospatial data type support||Yes||No||Yes||Yes||Yes|
|Geospatial indexing support||Yes||No||No||No||No|
|Full-text search indexes||Yes||No||Yes[b]||No||No|
|Cluster database support||No||No||No||No||Yes|
|Foreign key support||No||No||Yes||No||No|
|Backup / point-in-time recovery[g]||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 utilizes hash indexes internally for its Adaptive Hash Index feature.
[b] InnoDB support for FULLTEXT indexes is available in MySQL 5.6.4 and higher.
[c] Compressed MyISAM tables are supported only when using the compressed row format. Tables using the compressed row format with MyISAM are read only.
[d] Compressed InnoDB tables require the InnoDB Barracuda file format.
[e] Implemented in the server (via encryption functions), rather than in the storage engine.
[f] Implemented in the server, rather than in the storage engine.
[g] Implemented in the server, rather than in the storage engine.