|May 23, 1995 (1995-05-23)
|5.1.45 (March 17, 2010; 6 days ago (2010-03-17)) [+/−]
|5.5.2 (February 14, 2010; 37 days ago (2010-02-14)) [+/−]
|GNU General Public License (version 2, with linking exception) or proprietary EULA
MySQL is a relational database management system (RDBMS) that runs as a server providing multi-user access to a number of databases. MySQL is officially pronounced /maɪˌɛskjuːˈɛl/ (“My S-Q-L”),but is often pronounced /maɪsiːˈkwɛl/ (“Micey Quell”) or /maɪˈsiːkwəl/ (“My Sequel”). It is named for original developer Michael Widenius‘s daughter My.
The MySQL development project has made its source code available under the terms of the GNU General Public License, as well as under a variety of proprietary agreements. MySQL is owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now owned by Sun Microsystems, a subsidiary of Oracle Corporation.
Members of the MySQL community have created several forks such as Drizzle and MariaDB. Both forks were in progress long before the Oracle acquisition (Drizzle was announced 8 months before the Sun acquisition).
Free-software projects that require a full-featured database management system often use MySQL. Such projects include (for example) WordPress, phpBB, Drupal and other software built on the LAMP software stack. MySQL is also used in many high-profile, large-scale World Wide Web products including Wikipedia, Google and Facebook.
Many web applications use MySQL as the database component of a LAMP software stack. Its popularity for use with web applications is closely tied to the popularity of PHP, which is often combined with MySQL. Several high-traffic web sites (including Flickr, Facebook, Wikipedia, Google (though not for searches), Nokia and YouTube) use MySQL for data storage and logging of user data.
Platforms and interfaces
MySQL works on many different system platforms, including AIX, BSDi, FreeBSD, HP-UX, i5/OS, Linux, Mac OS X, NetBSD, Novell NetWare, OpenBSD, OpenSolaris, eComStation, OS/2 Warp, QNX, IRIX, Solaris, Symbian, SunOS, SCO OpenServer, SCO UnixWare, Sanos, Tru64 and Microsoft Windows. A port of MySQL to OpenVMS also exists.
All major programming languages with language-specific APIs include Libraries for accessing MySQL databases. In addition, an ODBC interface called MyODBC allows additional programming languages that support the ODBC interface to communicate with a MySQL database, such as ASP or ColdFusion. The MySQL server and official libraries are mostly implemented in ANSI C/ANSI C++.
Management and Graphical Frontends
MySQL Workbench in Windows, displaying the Home Screen which streamlines use of its full capabilities
MySQL is primarily an RDBMS and therefore ships with no GUI tools to administer MySQL databases or manage data contained within. Users may use the included command-line tools, or download MySQL Frontends from various parties that have developed desktop software and web applications to manage MySQL databases, build database structure, and work with data records.
The official MySQL Workbench is a free integrated environment developed by MySQL AB, that enables users to graphically administer MySQL databases and visually design database structure. MySQL Workbench replaces the previous package of software, MySQL GUI Tools. Similar to other third-party packages but still considered the authoritative MySQL frontend, MySQL Workbench lets users manage the following:
- Database design & modeling
- SQL development — replacing MySQL Query Browser
- Database administration — replacing MySQL Administrator
MySQL Workbench is available in two editions, the regular free and open source Community Edition which may be downloaded from the MySQL website, and the proprietary Standard Edition which extends and improves the feature set of the Community Edition.
Several other third-party proprietary and free graphical administration applications (or “Frontends”) are available that integrate with MySQL and enable users to work with database structure and data visually. Some well-known frontends are:
- phpMyAdmin – a free Web-based frontend widely installed by Web hosts worldwide, since it is developed in PHP and only requires the LAMP stack.
- HeidiSQL – a full featured free frontend that runs on Windows, and can connect to local or remote MySQL servers to manage databases, tables, column structure, and individual data records. Also supports specialised GUI features for date/time fields and enumerated multiple-value fields.
- Adminer – a free MySQL frontend written in one PHP script, capable of managing multiple databases, with many CSS skins available.
- Navicat – a series of proprietary graphical database management applications, developed for Windows, Macintosh and Linux.
- Other available proprietary MySQL frontends include Aqua Data Studio, dbForge Studio for MySQL, Epictetus, Oracle SQL Developer, SchemaBank, SQLyog, SQLPro SQL Client, Toad and Toad Data Modeler.
MySQL can be built and installed manually from source code, but this can be tedious so it is more commonly installed from a binary package unless special customizations are required. On most Linux distributions the package management system can download and install MySQL with minimal effort, though further configuration is often required to adjust security and optimization settings.
Though MySQL began as a low-end alternative to more powerful proprietary databases, it has gradually evolved to support higher-scale needs as well.
It is still most commonly used in small to medium scale single-server deployments, either as a component in a LAMP based web application or as a standalone database server. Much of MySQL’s appeal originates in its relative simplicity and ease of use, which is enabled by an ecosystem of open source tools such as phpMyAdmin.
In the medium range, MySQL can be scaled by deploying it on more powerful hardware, such as a multi-processor server with gigabytes of memory.
There are however limits to how far performance can scale on a single server, so on larger scales, multi-server MySQL deployments are required to provide improved performance and reliability. A typical high-end configuration can include a powerful master database which handles data write operations and is replicated to multiple slaves that handle all read operations. The master server synchronizes continually with its slaves so in the event of failure a slave can be promoted to become the new master, minimizing downtime. Further improvements in performance can be achieved by caching the results from database queries in memory using memcached, or breaking down a database into smaller chunks called shards which can be spread across a number of distributed server clusters.
- A broad subset of ANSI SQL 99, as well as extensions
- Cross-platform support
- Stored procedures
- Updatable Views
- True Varchar support
- Strict mode
- X/Open XA distributed transaction processing (DTP) support; two phase commit as part of this, using Oracle’s InnoDB engine
- Independent storage engines (MyISAM for read speed, InnoDB for transactions and referential integrity, MySQL Archive for storing historical data in little space)
- Transactions with the InnoDB, BDB and Cluster storage engines; savepoints with InnoDB
- SSL support
- Query caching
- Sub-SELECTs (i.e. nested SELECTs)
- Replication support (i.e. Master-Master Replication & Master-Slave Replication) with one master per slave, many slaves per master, no automatic support for multiple masters per slave.
- Full-text indexing (Index (database)) and searching using MyISAM engine
- Embedded database library
- Partial Unicode support (UTF-8 and UCS-2 encoded strings are limited to the BMP)
- Partial ACID compliance (full compliance only when using the non-default storage engines InnoDB, BDB and Cluster)
- Shared-nothing clustering through MySQL Cluster
- Hot backup (via
mysqlhotcopy) under certain conditions
The developers release monthly versions of the MySQL Enterprise Server. The sources can be obtained either from MySQL’s customer-only Enterprise site or from MySQL’s Bazaar repository, both under the GPL license. The MySQL Community Server is published on an unspecified schedule under the GPL and contains all bug fixes that were shipped with the last MySQL Enterprise Server release. Binaries are no longer provided by MySQL for every release of the Community Server.
MySQL implements the following features, which some other RDBMS systems may not:
- Multiple storage engines, allowing one to choose the one that is most effective for each table in the application (in MySQL 5.0, storage engines must be compiled in; in MySQL 5.1, storage engines can be dynamically loaded at run time):
- Native storage engines (MyISAM, Falcon, Merge, Memory (heap), Federated, Archive, CSV, Blackhole, Cluster, Berkeley DB, EXAMPLE, and Maria)
- Partner-developed storage engines (InnoDB, solidDB, NitroEDB, Infobright (formerly Brighthouse), Kickfire, XtraDB, IBM DB2)
- Community-developed storage engines (memcache engine, httpd, PBXT, Revision Engine)
- Custom storage engines
- Commit grouping, gathering multiple transactions from multiple connections together to increase the number of commits per second.
Milestones in MySQL development include:
- Original development of MySQL by Michael Widenius and David Axmark beginning in 1994
- First internal release on 23 May 1995
- Windows version was released on 8 January 1998 for Windows 95 and NT
- Version 3.23: beta from June 2000, production release January 2001
- Version 4.0: beta from August 2002, production release March 2003 (unions)
- Version 4.01: beta from August 2003, Jyoti adopts MySQL for database tracking
- Version 4.1: beta from June 2004, production release October 2004 (R-trees and B-trees, subqueries, prepared statements)
- Version 5.0: beta from March 2005, production release October 2005 (cursors, stored procedures, triggers, views, XA transactions)
The developer of the Federated Storage Engine states that “The Federated Storage Engine is a proof-of-concept storage engine”, but the main distributions of MySQL version 5.0 included it and turned it on by default. Documentation of some of the short-comings appears in “MySQL Federated Tables: The Missing Manual”
- Sun Microsystems acquired MySQL AB on 26 February 2008.
- Version 5.1: production release 27 November 2008 (event scheduler, partitioning, plugin API, row-based replication, server log tables)
Version 5.1 contained 20 known crashing and wrong result bugs in addition to the 35 present in version 5.0.
- Oracle acquired Sun Microsystems on January 27, 2010.Oracle and Sun
The MySQL 6 roadmap outlines support for:
- Referential integrity and Foreign key support for all storage engines is targeted for release in MySQL 6.1 (although it has been present since version 3.23.44 for InnoDB).
- Support for supplementary Unicode characters, beyond the 65,536 characters of the Basic Multilingual Plane (BMP); announced for MySQL 6.0.
- A new storage engine called Falcon. A preview of Falcon is available on MySQL’s website.
Support and licensing
Via MySQL Enterprise MySQL AB offers support itself, including a 24/7 service with 30-minute response time. The support team has direct access to the developers as necessary to handle problems. In addition, it hosts forums and mailing lists, employees and other users are often available in several IRC channels providing assistance.
In addition to official product support from Sun, other companies offer support and services related to usage of MySQL. For example, Pythian
Buyers of MySQL Enterprise have access to binaries and software certified for their particular operating system, and access to monthly binary updates with the latest bug-fixes. Several levels of Enterprise membership are available, with varying response times and features ranging from how to and emergency support through server performance tuning and system architecture advice. The MySQL Network Monitoring and Advisory Service monitoring tool for database servers is available only to MySQL Enterprise customers.
Potential users can install MySQL Server as free software under the GNU General Public License (GPL), and the MySQL Enterprise subscriptions include a GPL version of the server, with a traditional proprietary version available on request at no additional cost for cases where the intended use is incompatible with the GPL.
Both the MySQL server software itself and the client libraries use dual-licensing distribution. Users may choose the GPL, which MySQL has extended with a FLOSS License Exception. It allows Software licensed under other OSI-compliant open source licenses, which are not compatible to the GPL, to link against the MySQL client libraries.
Customers that do not wish to follow the terms of the GPL may purchase a proprietary license.
Corporate backing history
In October 2005, Oracle Corporation acquired Innobase OY, the Finnish company that developed the third-party InnoDB storage engine that allows MySQL to provide such functionality as transactions and foreign keys. After the acquisition, an Oracle press release mentioned that the contracts that make the company’s software available to MySQL AB would be due for renewal (and presumably renegotiation) some time in 2006. During the MySQL Users Conference in April 2006, MySQL issued a press release that confirmed that MySQL and Innobase OY agreed to a “multi-year” extension of their licensing agreement..
In February 2006, Oracle Corporation acquired Sleepycat Software, makers of the Berkeley DB, a database engine providing the basis for another MySQL storage engine. This had little effect, as Berkeley DB was not widely used, and was deprecated (due to lack of use) in MySQL 5.1.12, a pre-GA release of MySQL 5.1 released in October 2006.
In January 2008, Sun Microsystems bought MySQL for USD $1 billion.
In April 2009, Oracle Corporation entered into an agreement to purchase Sun Microsystems, then owners of the MySQL intellectual property. Sun’s board of directors unanimously approved the deal, it was also approved by Sun’s shareholders, and by the U.S. government on August 20, 2009. On December 14, 2009, Oracle pledged to continue to enhance MySQL. as it had done for the previous 4 years. The Oracle acquisition was approved by the European Commission on January 21, 2010.