MySQL

Developer(s)	Oracle (formerly Sun, formerly MySQL AB)
Initial release	23 May 1995 (1995-05-23)
Stable release	5.5.25 / 30 May 2012; 20 days ago (2012-05-30)[1]
Preview release	5.6.5 / 10 April 2012; 2 months ago (2012-04-10)[2]
Written in	C, C++[3]
Operating system	Cross-platform
Available in	English
Type	RDBMS
License	GNU General Public License (version 2, with linking exception) or proprietary EULA
Website	www.mysql.com dev.mysql.com

MySQL ( /maɪ ˌɛskjuːˈɛl/ "My S-Q-L",^[4] officially, but also called /maɪ ˈsiːkwəl/ "My Sequel") is the world's most used^[5] open source relational database management system (RDBMS)^[6] that runs as a server providing multi-user access to a number of databases. It is named after co-founder Michael Widenius' daughter, My.^[7] The SQL phrase stands for Structured Query Language.^[8]

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 was owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now owned by Oracle Corporation.^[9]

Free-software-open source projects that require a full-featured database management system often use MySQL. For commercial use, several paid editions are available, and offer additional functionality. Applications which use MySQL databases include: TYPO3, Joomla, WordPress, phpBB, MyBB, 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^[10] (though not for searches), Facebook,^[11] and Twitter.^[12]

Contents 1 Uses 2 Platforms and interfaces 3 Management and graphical frontends 3.1 Official 3.2 Third-party 3.3 Command line 4 Deployment 4.1 Cloud-based deployment 5 Features 5.1 Distinguishing features 5.2 Limitations 6 Product history 6.1 Versions 6.2 Future releases 7 Licensing and support 8 Corporate backing history 9 Conflict with NuSphere 10 Forks 11 See also 12 References 13 External links

  Uses

MySQL is a popular choice of database for use in web applications, and is a central component of the widely used LAMP open source web application software stack—LAMP is an acronym for "Linux, Apache, MySQL, Perl/PHP/Python".

MySQL is an open source database management system and is used in some of the most frequently visited websites on the Internet, including Flickr,^[13] Nokia.com,^[14] YouTube^[15] and as previously mentioned, Wikipedia,^[16] Google,^[17] Facebook^[18][19] and Twitter.^[12]

  Platforms and interfaces

MySQL is written in C and C++. Its SQL parser is written in yacc, and a home-brewed lexical analyzer named sql_lex.cc.^[20]

MySQL works on many different system platforms, including AIX, BSDi, FreeBSD, HP-UX, eComStation, i5/OS, IRIX, Linux, Mac OS X, Microsoft Windows, NetBSD, Novell NetWare, OpenBSD, OpenSolaris, OS/2 Warp, QNX, Solaris, Symbian, SunOS, SCO OpenServer, SCO UnixWare, Sanos and Tru64. A port of MySQL to OpenVMS also exists.^[21]

Many programming languages with language-specific APIs include libraries for accessing MySQL databases. These include MySQL Connector/Net for integration with Microsoft's Visual Studio (languages such as C# and VB are most commonly used) and the JDBC driver for Java. 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 a MySQL adapter, allowing direct interaction between a MySQL database and any web client via structured URLs.

  Management and graphical frontends

MySQL is primarily an RDBMS and ships with no GUI tools to administer MySQL databases or manage data contained within the databases. Users may use the included command line tools,^{[citation needed]} or download MySQL front-ends from various parties that have developed desktop software and web applications to manage MySQL databases, build database structures, and work with data records.

  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 structures. 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.

  Third-party

Third-party proprietary and free graphical administration applications (or "front ends") are available that integrate with MySQL and enable users to work with database structure and data visually. Some well-known front ends, in alphabetical order, are:

• Adminer – a free MySQL front end written in one PHP script, capable of managing multiple databases, with many CSS skins available.
• DaDaBIK – an Open Source software, written in PHP, which provides a customizable Web CRUD/front-end to a database.
• DBEdit – a free front end for MySQL and other databases.
• dbForge GUI Tools — a set of tools for database management that includes separate applications for schema comparison and synchronization, data comparison and synchronization, and building queries.
• HeidiSQL – a full featured free front end 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.^[22]
• LibreOffice Base - LibreOffice Base allows the creation and management of databases, preparation of forms and reports that provide end users easy access to data. Like Access, it can be used as a front-end for various database systems, including Access databases (JET), ODBC data sources, and MySQL or PostgreSQL.^[23]
• Navicat – a series of proprietary graphical database management applications, developed for Windows, Macintosh and Linux.
• OpenOffice.org – OpenOffice.org Base can manage MySQL databases. (You must install all of the OpenOffice.org suite. It is free and open source.)
• phpMyAdmin – a free Web-based front end widely installed by Web hosts worldwide, since it is developed in PHP and is included in the convenient LAMP stack, MAMP, and WAMP software bundle installers.
• SQLBuddy - a free Web-based front end, developed in PHP.
• Sequel Pro - a free, open-source front end for OS X.
• SQLYog - a free community UI for MySQL.
• Toad for MySQL – a free development and administration front end for MySQL from Quest Software

Other available proprietary MySQL front ends include dbForge Studio for MySQL, Epictetus, Oracle SQL Developer, SchemaBank, SQLPro SQL Client, Toad Data Modeler,

  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, which is written in Perl.

  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.^[24] 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.^[25]

  Cloud-based deployment

Another deployment option is running MySQL on cloud computing platforms such as Amazon EC2. There are two common deployment models for MySQL on the cloud:

• Virtual Machine Image - cloud users can upload a machine image of their own with MySQL installed, or use a ready-made machine image with an optimized installation of MySQL on it, such as the one provided by Amazon EC2.^[26]
• MySQL as a Service - some cloud platforms offer MySQL "as a service". In this configuration, application owners do not have to install and maintain the MySQL database on their own. Instead, the database service provider takes responsibility for installing and maintaining the database, and application owners pay according to their usage.^[27] Two notable cloud-based MySQL services are the Amazon Relational Database Service, and the Xeround Cloud Database, which runs on EC2, Rackspace and Heroku.

A third option is managed MySQL hosting on the cloud, where the database is not offered as a service, but the cloud provider hosts the database and manages it on the application owner's behalf. As of 2011, of the major cloud providers, only Rackspace offers managed hosting for MySQL databases.^[28]

  Features

As of April 2009^[update], MySQL offered MySQL 5.1 in two different variants: the open source MySQL Community Server and the commercial Enterprise Server. MySQL 5.5 is offered under the same licences.^[29] They have a common code base and include the following features:

• A broad subset of ANSI SQL 99, as well as extensions
• Cross-platform support
• Stored procedures
• Triggers
• Cursors
• Updatable Views
• Information schema
• Strict mode (ensures MySQL does not truncate or otherwise modify data to conform to an underlying data type, when an incompatible value is inserted into that type)
• 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, 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 and searching using MyISAM engine
• Embedded database library
• Partial Unicode support (UTF-8 and UCS-2 encoded strings are limited to the BMP)
• ACID compliance when using transaction capable storage engines (InnoDB and Cluster)^[30]
• Partititoned tables with pruning of partitions in optimiser
• Shared-nothing clustering through MySQL Cluster
• Hot backup (via mysqlhotcopy) under certain conditions^[31]

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

  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):
  • Native storage engines (MyISAM, Falcon, Merge, Memory (heap), Federated, Archive, CSV, Blackhole, Cluster, EXAMPLE, Maria, and InnoDB, which was made the default as of 5.5)
  • Partner-developed storage engines (solidDB, NitroEDB, ScaleDB, TokuDB, Infobright (formerly Brighthouse), Kickfire, XtraDB, IBM DB2).^[32] InnoDB used to be a partner-developed storage engine, but with recent acquisitions, Oracle now owns both MySQL core and InnoDB.
  • 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. (PostgreSQL has an advanced form of this functionality^[33])

  Limitations

MySQL does not currently comply with the SQL standard for some of the implemented functionality, including issues like silent ignore of standard SQL syntax, including silent ignore of check constraints, foreign key references, and other features used to enforce business logic consistency.^[34] Triggers are currently limited to one per action / timing, i.e. maximum one after insert and one before insert on the same table.^[35] There are no triggers on views.^[35]

  Product history

Milestones in MySQL development include:

• Original development of MySQL by Michael Widenius and David Axmark beginning in 1994^[36]
• First internal release on 23 May 1995
• Windows version was released on 8 January 1998 for Windows 95 and NT
• Version 3.19: End of 1996, from www.tcx.se
• Version 3.20: January 1997
• Version 3.21: production release 1998, from www.mysql.com
• Version 3.22: alpha, beta from 1998
• Version 3.23: beta from June 2000, production release 22 January 2001^[37]
• Version 4.0: beta from August 2002, production release March 2003 (unions)
• Version 4.01: beta from August 2003, Jyoti^{[clarification needed][citation needed]} 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",^[38] 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".^[39]

• Sun Microsystems acquired MySQL AB on 26 February 2008.^[9]
• 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 (almost all fixed as of release 5.1.51).^[40]

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.^[41]

• Oracle acquired Sun Microsystems on 27 January 2010.^[42]
• MySQL Server 5.5 is currently generally available (as of December 2010^[update]). Enhancements and features include:
  • The default storage engine is InnoDB, which supports transactions and referential integrity constraints.
  • Improved InnoDB I/O subsystem^[43]
  • Improved SMP support^[44]
  • 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.

  Versions

^{[45][46][47][48][49][50]}

  Future releases

MySQL Server 6.0.11-alpha was announced^[51] on 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.

MySQL 5.6, a development milestone release, was announced at the MySQL users conference 2011. New features include performance improvements to the query optimizer, higher transactional throughput in InnoDB, new NoSQL-style memcached APIs, improvements to partitioning for querying and managing very large tables, improvements to replication and better performance monitoring by expanding the data available through the PERFORMANCE_SCHEMA.^[52] In July further previews with a BINLOG API, group commit, and InnoDB full text searching were released.

  Licensing and support

Both the MySQL server software itself and the client libraries use dual-licensing distribution. They are offered under GPL,^[53] beginning from 28 June 2000^[54] (which Oracle has extended with a FLOSS License Exception)^[55] or to use a proprietary license.^[56]

First of all support can be obtained from the official manual, which is available at http://dev.mysql.com/doc/refman/5.5/en/index.html. Free support additionally is available in different IRC channels and forums.

Apart from that Oracle offers paid support via their MySQL Enterprise products. They differ in the scope of services and in price.

  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.^[57] 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.^[58]

In February 2006, Oracle Corporation acquired Sleepycat Software,^[59] 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.^[60]

In January 2008, Sun Microsystems bought MySQL for $1 billion.^[61]

In April 2009, Oracle Corporation entered into an agreement to purchase Sun Microsystems,^[62] then owners of MySQL copyright and trademark. Sun's board of directors unanimously approved the deal, it was also approved by Sun's shareholders, and by the U.S. government on 20 August 2009.^[63] On 14 December 2009, Oracle pledged to continue to enhance MySQL^[64] as it had done for the previous four years.

A movement against Oracle's acquisition of MySQL, to "Save MySQL"^[65] from Oracle was started by one of the MySQL founders, Monty Widenius. The petition of 50,000+ developers and users called upon the European Commission to block approval of the acquisition. At the same time, several Free Software opinion leaders (including Eben Moglen, Pamela Jones of Groklaw, Jan Wildeboer and Carlo Piana, who also acted as co-counsel in the merger regulation procedure) advocated for the unconditional approval of the merger.^{[citation needed]} As part of the negotiations with the European Commission, Oracle committed that MySQL server will continue to use the dual-licensing strategy long used by MySQL AB with commercial and GPL versions available until at least 2015. The antitrust of the EU had been "pressuring it to divest MySQL as a condition for approval of the merger." But, as revealed by Wikileaks, the US Department of Justice and Antitrust, at the request of Oracle, pressured the EU to unconditionally approve the merger.^[66] The Oracle acquisition was eventually unconditionally approved by the European Commission on 21 January 2010.^[67]

Meanwhile, Monty Widenius has released a GPL-only fork, MariaDB. MariaDB is based on the same code base as MySQL server 5.1 and strives to maintain compatibility with Oracle provided versions.^[68]

  Conflict with NuSphere

In 15 June of 2001 NuSphere sued MySQL AB, TcX DataKonsult AB and its original authors Michael ("Monty") Widenius and David Axmark in U.S District Court in Boston.^{[69] [70]} In 2002, MySQL AB sued Progress NuSphere for copyright and trademark infringement in United States district court. NuSphere had allegedly violated MySQL's copyright by linking MySQL's GPL'ed code with NuSphere Gemini table without being in compliance with the license. After a preliminary hearing before Judge Patti Saris on 27 February 2002, the parties entered settlement talks and eventually settled.^[71] After the hearing, FSF commented that "Judge Saris made clear that she sees the GNU GPL to be an enforceable and binding license."^[72]

  Forks

• Drizzle – a fork targeted at the web-infrastructure and cloud computing markets. The developers of the product describe it as a "smaller, slimmer and (hopefully) faster version of MySQL". As such is planned to have many common MySQL features stripped out, including stored procedures, query cache, prepared statements, views, and triggers. This is a partial rewrite of the server that does not maintain compatibility with MySQL.
• MariaDB – a community-developed branch of the MySQL database, the impetus being the community maintenance of its free status under GPL as opposed to any uncertainty of MySQL license status under its current ownership by Oracle. The intent also being to maintain high fidelity with MySQL, ensuring a "drop-in" replacement capability with library binary equivalency and exacting matching with MySQL APIs and commands. It includes the XtraDB storage engine as a replacement for InnoDB.
• Percona Server – a fork that includes the XtraDB storage engine. It is an enhanced version of MySQL that is fully compatible, and deviates as little as possible from it, while still providing beneficial new features, better performance, and improved instrumentation for analysis of performance and usage.
• OurDelta – a fork compiled with various patches, including patches from MariaDB, Percona, and Google.

  See also

• Comparison of database tools
• Comparison of MySQL database engines
• Comparison of relational database management systems
• Firebird (database server)
• HSQLDB (Native engine used by Open Office, installs with the suite. Open Office can connect to others, too.)
• Ingres (database)
• Oracle RDBMS
• PostgreSQL
• Solution stack

  References

  External links

Wikibooks has more on the topic of MySQL

Wikimedia Commons has media related to: MySQL

• Official website
• MySQL on Twitter
• MySQL on Facebook
• MySQL site at Oracle.com
• Planet MySQL - an aggregation of MySQL-related blogs
• MySQL Blog
• Interview with David Axmark, MySQL co-founder Video
• MySQL at the Open Directory Project

MySQL Editions MySQL · MySQL Enterprise · MySQL Cluster MySQL tools MySQL Workbench · SQLyog · phpMyAdmin · HeidiSQL · Navicat Storage engines MyISAM · Falcon · InnoDB · MySQL Federated · MySQL Archive · Aria · Xeround Forks Drizzle · MariaDB

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