- 13 Storage Engines
- 13.1 Overview of MySQL Storage Engine Architecture
- 13.2 Supported Storage Engines
- 13.3 Setting the Storage Engine
- 13.4 The MyISAM Storage Engine
- 13.5 The Maria Storage Engine
- 13.6 The InnoDB Storage Engine
- 13.7 The MERGE Storage Engine
- 13.8 The MEMORY (HEAP) Storage Engine
- 13.9 The EXAMPLE Storage Engine
- 13.10 The FEDERATED Storage Engine
- 13.11 The ARCHIVE Storage Engine
- 13.12 The CSV Storage Engine
- 13.13 The BLACKHOLE Storage Engine
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Maria is a crash safe version of
MyISAM. The Maria storage
engine supports all of the main functionality of the
MyISAM engine, but includes recovery support (in
the event of a system crash), full logging (including
CREATE, DROP,
RENAME and
TRUNCATE operations), all
MyISAM row formats and a new
Maria specific row format.
Maria has been designed as a replacement for the
MyISAM storage engine, supporting the speed and
flexibility of the original MyISAM
implementation, in combination with MVCC transaction support. Within
the current release, a limited level of concurrency for
INSERT/UPDATE
and SELECT functionality is
supported. For more information, see
Section 13.5.6, “Maria Statement Concurrency”.
For more information on known bugs and limitations in
Maria, see Section 13.5.9, “Maria Open Bugs”
To create a Maria table you must specify the
engine when using the CREATE TABLE
statement:
mysql> CREATE TABLE maria_table (id int) ENGINE=Maria;
You can also use ALTER TABLE to
convert an existing table to the Maria engine:
mysql> ALTER TABLE myisam_table ENGINE=Maria;
Data in Maria tables is stored in three files:
table.frm— the standard MySQL FRM file containing the table definition.table.MAD— theMariadata file.table.MAI— theMariaindex file.
In addition, Maria creates at least two
additional files in your standard datadir
directory:
maria_log.????????— theMarialog file. Each file is named numerically and sequentially, with new files automatically created when the log file limit has been reached. You can control the log file size usingmaria_log_file_sizeoption, and control the deletion of logs usingmaria_log_purge_type. The newly created files stay in place until deleted either automatically or manually.-
maria_log_control— a control file that holds information about the current state of theMariaengine.Warning
You should not delete the
maria_log_controlfile from an activeMariainstallation as it records information about the current state of theMariaengine, including information about the log files and the default page block size used for the log and data files.
The basic functionality of Maria matches the
functionality of MyISAM with a number of
differences. These are:
Two types of tables are supported. Non-crash safe tables (non-transactional) are written immediately to their corresponding data file. Transactional tables are crash safe and data is written into the
Marialog. For more information on the log, see Section 13.5.3, “MariaTransaction Log”. Data which had already been written to the log is then applied to the data and index files as the statement completes.Mariasupports auto-recovery in the event of a crash. For more information, see Section 13.5.4, “MariaRecovery”.Mariasupports a single writer and multiple readers. The writer supports bothINSERTandUPDATEoperations.MyISAMsupports only concurrentINSERTandSELECTstatements. For more information, see Section 13.5.6, “MariaStatement Concurrency”.Mariaprovides a new row format,PAGE. For more information, see Section 13.5.2, “MariaTable Options”. ExistingMyISAMrow formats are also supported on non-transactional tables.Mariasupports crash-safe operations over many statements by enclosing statements withinLOCK TABLESandUNLOCK TABLESstatements.
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