MySQLFrom Wikipedia, the free encyclopedia

Screenshot of the default MySQL command line.
Developer(s) MySQL AB (A subsidiary of Oracle Corporation)
Initial release May 23, 1995 (1995-05-23)
Stable release


(June 2, 2010; 47 days ago (2010-06-02)) [+/−]
Preview release


(April 9, 2010; 3 months ago (2010-04-09)) [+/−]
Written in C, C++
Operating system Cross-platform
Available in English
License GNU General Public License (version 2, with linking exception) or proprietary EULA

MySQL is a relational database management system (RDBMS)[1] that runs as a server providing multi-user access to a number of databases. MySQL is officially pronounced /maɪˌɛskjuːˈɛl/ ("My S-Q-L"),[2] but is often pronounced /maɪˈsiːkwəl/ ("My Sequel"). It is named for original developer Michael Widenius's daughter My.[3]

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.[4]

Members of the MySQL community have created several forks such as Drizzle, OurDelta, Percona Server, and MariaDB. All of these forks were in progress 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 and Facebook.



[edit] Uses

The "M" in the acronym of the popular LAMP software stack refers to MySQL. Its popularity for use with web applications is closely tied to the popularity of PHP (the "P" in LAMP). Several high-traffic web sites (including Flickr,[5] Facebook,[6][7] Wikipedia,[8] Google[9] (though not for searches), Nokia[10] and YouTube[11]) use MySQL for data storage and logging of user data.

[edit] Platforms and interfaces

MySQL code uses C and C++. The SQL parser uses yacc and a home-brewed lexer,[12]

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.[13]

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 HTSQL - URL based query method also ships with MySQL adapter allowing direct interaction with MySQL database from any web client via structured URLs. The MySQL server and official libraries are mostly implemented in ANSI C/ANSI C++.

[edit] 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,[14] 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.

[edit] Official

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.

[edit] Third party

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:

[edit] Command-Line

MySQL ships with a suite of command-line tools for tasks such as querying the database, backing up data, inspecting status, performing common tasks such as creating a database, and many more. A variety of third-party command-line tools is also available, including:

  • Maatkit, a set of power-user tools written in Perl
  • MySQL Sandbox, a set of scripts for quickly starting server instances for testing and development

[edit] Deployment

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.[16] 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.[17]

[edit] Features

As of April 2009, MySQL offers MySQL 5.1 in two different variants: the open source MySQL Community Server and the commercial Enterprise Server.[18] They have a common code base and include the following features:

The developers release monthly versions of the MySQL Server. The sources can be obtained from MySQL's web site or from MySQL's Bazaar repository, both under the GPL license.

[edit] Distinguishing features

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):
  • Commit grouping, gathering multiple transactions from multiple connections together to increase the number of commits per second.

[edit] Product history

Milestones in MySQL development include:

  • Original development of MySQL by Michael Widenius and David Axmark beginning in 1994[21]
  • 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",[22] 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.[4]
  • 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.[23]
MySQL 5.1 and 6.0 showed poor performance when used for data warehousing — partly due to its inability to utilize multiple CPU cores for processing a single query.[24]

[edit] Future releases

MySQL Server 5.5 is currently available in pre-release (as of June 2010). Enhancements and features include:

  • The default storage engine is InnoDB, which supports transactions and referential integrity constraints.
  • Semisynchronous replication.
  • SIGNAL and RESIGNAL statement in compliance with the SQL standard.
  • Support for supplementary Unicode character sets utf16, utf32, and utf8mb4.
  • New options for user-defined partitioning.

MySQL Server 6.0.11-alpha was announced May 22, 2009 as the last release of the 6.0 line. Future MySQL Server development uses a New Release Model. Features developed for 6.0 are being incorporated into future releases.

[edit] Support and licensing

MySQL AB offers support via their MySQL Enterprise product, 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.

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.[25]

Both the MySQL server software itself and the client libraries use dual-licensing distribution. Users may choose the GPL,[26] 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.[27]

Customers that do not wish to follow the terms of the GPL may purchase a proprietary license.[28]

Like many open-source programs, MySQL has trademarked its name, which others may use only with the trademark holder's permission.[29]

[edit] 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.[30] 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.[31]

In February 2006, Oracle Corporation acquired Sleepycat Software,[32] 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.[33]

In January 2008, Sun Microsystems bought MySQL for USD $1 billion.[34]

In April 2009, Oracle Corporation entered into an agreement to purchase Sun Microsystems,[35] 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.[36] On December 14, 2009, Oracle pledged to continue to enhance MySQL[37] as it had done for the previous four years. The Oracle acquisition was approved by the European Commission on January 21, 2010.[38]

A movement against Oracle's acquisition of MySQL has called for the petition of 50,000 developers. It was started by the creator of MySQL, Monty Widenius. The movement attempted to call for help to save MySQL from Oracle. Some versions of mySQL may still be free and open source for the next 4-5 years. Meanwhile, Monty Widenius has released mySQL's free and open source replacement, MariaDB. MariaDB is based on the same database engine as mySQL.[39]

[edit] Forks of MySQL

MySQL forks include Drizzle, OurDelta, Percona Server, and MariaDB.

[edit] See also

Frontend applications:

Other RDBMS:

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