InnoDB is the default storage engine in
InnoDB is a
transaction-safe (ACID compliant) storage engine for MySQL that has
commit, rollback, and crash-recovery capabilities to protect user
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
InnoDB also supports
FOREIGN KEY referential-integrity constraints.
Unless you have configured a different default storage engine,
CREATE TABLE statement
ENGINE= clause creates an
If you use
MyISAM tables but are not
committed to them for technical reasons, you may find
InnoDB tables beneficial for the following
If your server crashes because of a hardware or software issue, regardless of what was happening in the database at the time, you don't need to do anything special after restarting the database.
InnoDBcrash recovery automatically finalizes any changes that were committed before the time of the crash, and undoes any changes that were in process but not committed. Just restart and continue where you left off.
InnoDBbuffer pool caches table and index data as the data is accessed. Frequently used data is processed directly from memory. This cache applies to many types of information, and speeds up processing.
If you split up related data into different tables, you can set up foreign keys that enforce referential integrity. Update or delete data, and the related data in other tables is updated or deleted automatically. Try to insert data into a secondary table without corresponding data in the primary table, and the bad data gets kicked out automatically.
If data becomes corrupted on disk or in memory, a checksum mechanism alerts you to the bogus data before you use it.
When you design your database with appropriate primary key columns for each table, operations involving those columns are automatically optimized. It is very fast to reference the primary key columns in
GROUP BYclauses, and join operations.
Inserts, updates, and deletes are optimized by an automatic mechanism called change buffering.
InnoDBnot only allows concurrent read and write access to the same table, it caches changed data to streamline disk I/O.
Performance benefits are not limited to giant tables with long-running queries. When the same rows are accessed over and over from a table, a feature called the Adaptive Hash Index takes over to make these lookups even faster, as if they came out of a hash table.
You can compress tables and associated indexes.
You can create and drop indexes with much less impact on performance and availability.
Truncating a file_per_table tablespace is very fast, and can free up disk space for the operating system to reuse, rather than freeing up space within the system tablespace that only
You can monitor the internal workings of the storage engine by querying INFORMATION_SCHEMA tables.
You can monitor the performance details of the storage engine by querying Performance Schema tables.
InnoDB-specific tuning techniques you can
apply in your application code, see
Section 8.5, “Optimizing for InnoDB Tables”.
MySQL continues to work on addressing use cases that formerly
MyISAM tables. In MySQL 5.6 and higher:
InnoDBcan perform full-text search using the
FULLTEXTindex type. See Section 220.127.116.11, “InnoDB FULLTEXT Indexes” for details.
InnoDBnow performs better with read-only or read-mostly workloads. Automatic optimizations apply to
InnoDBqueries in autocommit mode, and you can explicitly mark transactions as read-only with the syntax
START TRANSACTION READ ONLY. See Section 8.5.3, “Optimizing InnoDB Read-Only Transactions” for details.
Applications distributed on read-only media can now use
InnoDBtables. See Section 14.4.2, “Configuring InnoDB for Read-Only Operation” for details.
Some general best practices for
Using joins wherever data is pulled from multiple tables based on identical ID values from those tables. For fast join performance, define foreign keys on the join columns, and declare those columns with the same data type in each table. Adding foreign keys ensures that referenced columns are indexed, which can improve performance. Foreign keys also propagate deletes or updates to all affected tables, and prevent insertion of data in a child table if the corresponding IDs are not present in the parent table.
Turning off autocommit. Committing hundreds of times a second puts a cap on performance (limited by the write speed of your storage device).
Grouping sets of related DML operations into transactions, by bracketing them with
COMMITstatements. While you don't want to commit too often, you also don't want to issue huge batches of
DELETEstatements that run for hours without committing.
InnoDBcan handle multiple sessions all reading and writing to the same table at once, without sacrificing reliability or high performance. To get exclusive write access to a set of rows, use the
SELECT ... FOR UPDATEsyntax to lock just the rows you intend to update.
innodb_file_per_tableoption to put the data and indexes for individual tables into separate files, instead of in a single giant system tablespace. This setting is required to use some of the other features, such as table compression and fast truncation.
innodb_file_per_tableoption is enabled by default as of MySQL 5.6.6.
Evaluating whether your data and access patterns benefit from the
InnoDBtable compression feature (
ROW_FORMAT=COMPRESSED) on the
CREATE TABLEstatement. You can compress
InnoDBtables without sacrificing read/write capability.
Running your server with the option
--sql_mode=NO_ENGINE_SUBSTITUTIONto prevent tables being created with a different storage engine if there is an issue with the engine specified in the
InnoDB is not your default storage engine, you
can determine if your database server or applications work correctly
InnoDB by restarting the server with
defined on the command line or with
defined in the
[mysqld] section of the
my.cnf configuration file.
Since changing the default storage engine only affects new tables as
they are created, run all your application installation and setup
steps to confirm that everything installs properly. Then exercise
all the application features to make sure all the data loading,
editing, and querying features work. If a table relies on some
MyISAM-specific feature, you'll receive an error;
ENGINE=MyISAM clause to the
CREATE TABLE statement to avoid the
If you did not make a deliberate decision about the storage engine,
and you just want to preview how certain tables work when they're
InnoDB, issue the command
ALTER TABLE table_name
ENGINE=InnoDB; for each table. Or, to run test queries and
other statements without disturbing the original table, make a copy
CREATE TABLE InnoDB_Table (...) ENGINE=InnoDB AS SELECT * FROM MyISAM_Table;
To get a true idea of the performance with a full application under a realistic workload, install the latest MySQL server and run benchmarks.
Test the full application lifecycle, from installation, through heavy usage, and server restart. Kill the server process while the database is busy to simulate a power failure, and verify that the data is recovered successfully when you restart the server.
Test any replication configurations, especially if you use different MySQL versions and options on the master and the slaves.
To verify that
InnoDB is the default storage
InnoDBis not present, you have a
mysqldbinary that was compiled without
InnoDBsupport and you need to get a different one.
InnoDBis present but disabled, go back through your startup options and configuration file and get rid of any