The MySQL server software itself and the client libraries use dual-licensing distribution. They are offered under GPL version 2, or a proprietary license.
Support can be obtained from the official manual. Free support additionally is available in different IRC channels and forums. Oracle offers paid support via its MySQL Enterprise products. They differ in the scope of services and in price. Additionally, a number of third party organisations exist to provide support and services, including MariaDB and Percona.
MySQL has received positive reviews, and reviewers noticed it "performs extremely well in the average case" and that the "developer interfaces are there, and the documentation (not to mention feedback in the real world via Web sites and the like) is very, very good". It has also been tested to be a "fast, stable and true multi-user, multi-threaded sql database server".
MySQL was created by a Swedish company, MySQL AB, founded by David Axmark, Allan Larsson and Michael "Monty" Widenius. Original development of MySQL by Widenius and Axmark began in 1994. The first version of MySQL appeared on 23 May 1995. It was initially created for personal usage from mSQL based on the low-level language ISAM, which the creators considered too slow and inflexible. They created a new SQL interface, while keeping the same API as mSQL. By keeping the API consistent with the mSQL system, many developers were able to use MySQL instead of the (proprietarily licensed) mSQL antecedent.[dubious–discuss]
Additional milestones in MySQL development included:
First internal release on 23 May 1995
Version 3.19: End of 1996, from www.tcx.se
Version 3.20: January 1997
Windows version was released on 8 January 1998 for Windows 95 and NT
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
Version 4.0: beta from August 2002, production release March 2003 (unions).
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".
SIGNAL and RESIGNAL statement in compliance with the SQL standard.
Support for supplementary Unicode character sets utf16, utf32, and utf8mb4[note 1].
New options for user-defined partitioning.
MySQL Server 6.0.11-alpha was announced on 22 May 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.
The general availability of MySQL5.6 was announced in February 2013. New features included 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, TIMESTAMP column type that correctly stores milliseconds, improvements to replication, and better performance monitoring by expanding the data available through the PERFORMANCE_SCHEMA. The InnoDB storage engine also included support for full-text search and improved group commit performance.
The general availability of MySQL5.7 was announced in October 2015. As of MySQL 5.7.8, August 2015, MySQL supports a native JSON data type defined by RFC 7159.
MySQL Server 8.0 was announced in April 2018, including NoSQL Document Store, atomic and crash safe DDL sentences and JSON Extended syntax, new functions, such as JSON table functions, improved sorting, and partial updates. Previous MySQL Server 8.0.0-dmr (Milestone Release) was announced 12 September 2016.
Work on version 6 stopped after the Sun Microsystems acquisition. The MySQL Cluster product uses version 7. The decision was made to jump to version 8 as the next major version number.
Legal disputes and acquisitions
On 15 June 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 for "breach of contract, tortious interference with third party contracts and relationships and unfair competition".
In 2002, MySQL AB sued Progress NuSphere for copyright and trademark infringement in United States district court. NuSphere had allegedly violated MySQL AB'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. After the hearing, FSF commented that "Judge Saris made clear that she sees the GNU GPL to be an enforceable and binding license."
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 AB issued a press release that confirmed that MySQL AB 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 dropped (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 AB for $1 billion.
In April 2009, Oracle Corporation entered into an agreement to purchase Sun Microsystems, 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. On 14 December 2009, Oracle pledged to continue to enhance MySQL as it had done for the previous four years.
A movement against Oracle's acquisition of MySQL AB, to "Save MySQL" from Oracle was started by one of the MySQL AB 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, some Free Software opinion leaders (including 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. As part of the negotiations with the European Commission, Oracle committed that MySQL server will continue until at least 2015 to use the dual-licensing strategy long used by MySQL AB, with proprietary and GPL versions available. 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, at the request of Oracle, pressured the EU to approve the merger unconditionally. The European Commission eventually unconditionally approved Oracle's acquisition of MySQL AB on 21 January 2010.
In January 2010, before Oracle's acquisition of MySQL AB, Monty Widenius started a GPL-only fork, MariaDB. MariaDB is based on the same code base as MySQL server 5.5 and aims to maintain compatibility with Oracle-provided versions.
MySQL is offered under two different editions: the open source MySQL Community Server and the proprietary Enterprise Server. MySQL Enterprise Server is differentiated by a series of proprietary extensions which install as server plugins, but otherwise shares the version numbering system and is built from the same code base.
Commit grouping, gathering multiple transactions from multiple connections together to increase the number of commits per second.
The developers release minor updates of the MySQL Server approximately every two months. The sources can be obtained from MySQL's website or from MySQL's GitHub repository, both under the GPL license.
When using some storage engines other than the default of InnoDB, MySQL does not comply with the full SQL standard for some of the implemented functionality, including foreign key references. Check constraints are parsed but ignored by all storage engines before MySQL version 8.0.15.
Up until MySQL 5.7, triggers are limited to one per action / timing, meaning that at most one trigger can be defined to be executed after an INSERT operation, and one before INSERT on the same table. No triggers can be defined on views.
MySQL database's inbuilt functions like UNIX_TIMESTAMP() will return 0 after 03:14:07 UTC on 19 January 2038. Recently, there had been an attempt to solve the problem which had been assigned to the internal queue.
MySQL can be built and installed manually from source code, but 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 ('scaling up'), so on larger scales, multi-server MySQL ('scaling out') 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 continually pushes binlog events to connected 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.
mysqldump is a logical backup tool included with both community and enterprise editions of MySQL. It supports backing up from all storage engines. MySQL Enterprise Backup is a hot backup utility included as part of the MySQL Enterprise subscription from Oracle, offering native InnoDB hot backup, as well as backup for other storage engines.
XtraBackup is an open-source MySQL hot backup software program. Features include hot, non-locking backups for InnoDB storage, incremental backups, streaming, parallel-compressed backups, throttling based on the number of I/O operations per second, etc.
High availability software
Oracle MySQL offers a high availability solution with a mix of tools including the MySQL router and the MySQL shell. They are based on Group Replication, open source tools.
MariaDB offers a similar offer in terms of products 
In this implementation, 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.
A graphical user interface (GUI) is a type of interface that allows users to interact with electronic devices or programs through graphical icons and visual indicators such as secondary notation, as opposed to text-based interfaces, typed command labels or text navigation. GUIs are easier to learn than command-line interfaces (CLIs), which require commands to be typed on the keyboard.
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 are:
MySQL Workbench is the official integrated environment for MySQL. It was developed by MySQL AB, and 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 front end, MySQL Workbench lets users manage database design & modeling, SQL development (replacing MySQL Query Browser) and Database administration (replacing MySQL Administrator).
MySQL Workbench is available in two editions, the regular free and open sourceCommunity 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.
Adminer (formerly known as phpMinAdmin) is a free MySQL front end for managing content in MySQL databases (since version 2, it also works on PostgreSQL, Microsoft SQL Server, SQLite and Oracle databases). Adminer is distributed under the Apache License (or GPL v2) in the form of a single PHP file (around 300 KiB in size), and is capable of managing multiple databases, with many CSS skins available. Its author is Jakub Vrána who started to develop this tool as a light-weight alternative to phpMyAdmin, in July 2007.
ClusterControl is an end-to-end MySQL management system GUI that provides the ability to deploy, monitor, manage and scale MySQL instances from a single interface. It is developed by Severalnines.
The Community version of ClusterControl is free to use and lets the user deploy and monitor their MySQL instances. Advanced features like load balancing, backup & restore, failover, etc are part of a paid offering.
Database Workbench is a software application for development and administration of multiple relational databases using SQL, with interoperationality between different database systems, developed by Upscene Productions.
Because Databases Workbench supports multiple database systems, it can provide software developers with the same interface and development environment for these otherwise different database systems and also includes cross database tools.
Database Workbench supports the following relational databases: Oracle Database, Microsoft SQL Server, SQL Anywhere, Firebird, NexusDB, InterBase, MySQL and MariaDB. Database Workbench 5 runs on 32-bit or 64-bit Windows platforms. Under Linux, FreeBSD or macOS Database Workbench can operate using Wine.
DBeaver is an SQL client and a database administration tool. DBeaver includes extended support of following databases: MySQL and MariaDB, PostgreSQL, Oracle, DB2 (LUW), Exasol, SQL Server, Sybase, Firebird, Teradata, Vertica, Apache Phoenix, Netezza, Informix, Apache Derby, H2, SQLite and any other database which has a JDBC or ODBC driver. DBeaver is free and open source software that is distributed under the Apache License 2.0. The source code is hosted on GitHub.
DBEdit is a database editor, which can connect to an Oracle, DB2, MySQL and any database that provides a JDBC driver. It runs on Windows, Linux and Solaris. DBEdit is free and open source software and distributed under the GNU General Public License. The source code is hosted on SourceForge.
HeidiSQL, previously known as MySQL-Front, is a free and open source client, or frontend for MySQL (and for its forks like MariaDB and Percona Server), Microsoft SQL Server and PostgreSQL. HeidiSQL is developed by German programmer Ansgar Becker and a few other contributors in Delphi. To manage databases with HeidiSQL, users must login to a local or remote MySQL server with acceptable credentials, creating a session. Within this session users may manage MySQL Databases within the connected MySQL server, disconnecting from the server when done. Its feature set is sufficient for most common and advanced database, table and data record operations but remains in active development to move towards the full functionality expected in a MySQL Frontend.
LibreOffice Base allows the creation and management of databases, preparation of forms and reports that provide end users easy access to data. Like Microsoft Access, it can be used as a front-end for various database systems, including Access databases (JET), ODBC data sources, and MySQL or PostgreSQL
Navicat is a series of graphical database management and development software produced by PremiumSoft CyberTech Ltd. for MySQL, MariaDB, Oracle, SQLite, PostgreSQL and Microsoft SQL Server. It has an Explorer-like graphical user interface and supports multiple database connections for local and remote databases. Its design is made to meet the needs of a variety of audiences, from database administrators and programmers to various businesses/companies that serve clients and share information with partners.
Navicat is a cross-platform tool and works on Microsoft Windows, OSX and Linux platforms. Upon purchase, users are able to select a language for the software from eight available languages: English, French, German, Spanish, Japanese, Polish, Simplified Chinese and Traditional Chinese.
OpenOffice.org Base is freely available and can manage MySQL databases if the entire suite is installed.
phpMyAdmin is a free and open source tool written in PHP intended to handle the administration of MySQL with the use of a web browser. It can perform various tasks such as creating, modifying or deleting databases, tables, fields or rows; executing SQL statements; or managing users and permissions. The software, which is available in 78 languages, is maintained by The phpMyAdmin Project.
It can import data from CSV and SQL, and transform stored data into any format using a set of predefined functions, like displaying BLOB-data as images or download-links.
Sequel Pro is a free and open-source MacOS application for working with MySQL databases locally or remotely. It uses the freemium model, where the Gratis users are actually getting features to most of the basic services. It takes a SQL Table itself to manage these requests. It can handle the new "fun" UTF-8 features for newer unicode as well as having multiple GB tables without issue. 
SQLBuddy is an open-source web-based application written in PHP intended to handle the administration of MySQL and SQLite with the use of a Web browser. The project places an emphasis on ease of installation and a simple user interface.
SQLyog is a GUI tool available in free as well as paid versions. Data manipulations (e.g., insert, update, and delete) may be done from a spreadsheet-like interface. Its editor has syntax highlighting and various automatic formatting options. Both raw table data and a result set from a query can be manipulated. Its data search feature uses Google-like search syntax and translates to SQL transparently for the user. It has a backup tool for performing unattended backups. Backups may be compressed and optionally stored as a file-per-table as well as identified with a timestamp.
Toad for MySQL
Toad for MySQL is a software application from Dell Software that database developers, database administrators and data analysts use to manage both relational and non-relational databases using SQL. Toad supports many databases and environments. It runs on all 32-bit/64-bit Windows platforms, including Microsoft Windows Server, Windows XP, Windows Vista, Windows 7 and 8 (32-Bit or 64-Bit). Dell Software has also released a Toad Mac Edition. Dell provides Toad in commercial and trial/freeware versions. The freeware version is available from the ToadWorld.com community.
Webmin is a web-based system configuration tool for Unix-like systems, although recent versions can also be installed and run on Windows. With it, it is possible to configure operating system internals, such as users, disk quotas, services or configuration files, as well as modify and control open source apps, such as the Apache HTTP Server, PHP or MySQL.
Webmin is largely based on Perl, running as its own process and web server. It defaults to TCP port 10000 for communicating, and can be configured to use SSL if OpenSSL is installed with additional required Perl modules.
It is built around modules, which have an interface to the configuration files and the Webmin server. This makes it easy to add new functionality. Due to Webmin's modular design, it is possible for anyone who is interested to write plugins for desktop configuration.
Webmin also allows for controlling many machines through a single interface, or seamless login on other webmin hosts on the same subnet or LAN.
A command-line interface is a means of interacting with a computer program where the user issues commands to the program by typing in successive lines of text (command lines). MySQL ships with many command line tools, from which the main interface is the mysql client.
MySQL Utilities is a set of utilities designed to perform common maintenance and administrative tasks. Originally included as part of the MySQL Workbench, the utilities are a stand-alone download available from Oracle.
Percona Toolkit is a cross-platform toolkit for MySQL, developed in Perl. Percona Toolkit can be used to prove replication is working correctly, fix corrupted data, automate repetitive tasks, and speed up servers. Percona Toolkit is included with several Linux distributions such as CentOS and Debian, and packages are available for Fedora and Ubuntu as well. Percona Toolkit was originally developed as Maatkit, but as of late 2011, Maatkit is no longer developed.
Application programming interfaces
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 MySQL Connector/ODBC 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. Other drivers exists for languages like Python or Node.js.
A variety of MySQL forks exist, including the following.
MariaDB is a community-developed fork of the MySQL relational database management system intended to remain free under the GNU GPL. Being a fork of a leading open source software system, it is notable for being led by the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle. Contributors are required to share their copyright with the MariaDB Foundation. MariaDB intends to maintain high compatibility with MySQL, ensuring a "drop-in" replacement capability with library binary equivalency and exact matching with MySQL APIs and commands. There are some documented differences and incompatibilities between versions of MySQL and MariaDB, however, and some tools for interacting with MySQL, such as the MySQL Workbench, are not fully compatible with MariaDB. It includes the XtraDB storage engine for replacing InnoDB, as well as a new storage engine, Aria, that intends to be both a transactional and non-transactional engine perhaps even included in future versions of MySQL.
Percona Server for MySQL
Percona Server for MySQL, forked by Percona, aims to retain close compatibility to the official MySQL releases, while focusing on performance and increased visibility into server operations. Also included in Percona Server for MySQL is XtraDB, Percona's fork of the InnoDB Storage Engine. Percona freely includes a number of scalability, availability, security and backup features only available in MySQL's commercial Enterprise edition.
Drizzle was a free software/open source relational database management system (DBMS) that was forked from the now-defunct 6.0 development branch of the MySQL DBMS. Like MySQL, Drizzle had a client/server architecture and uses SQL as its primary command language. Drizzle was distributed under version 2 and 3 of the GNU General Public License (GPL) with portions, including the protocol drivers and replication messaging under the BSD license.
WebScaleSQL was a software branch of MySQL 5.6, and was announced on 27 March 2014 by Facebook, Google, LinkedIn and Twitter as a joint effort to provide a centralized development structure for extending MySQL with new features specific to its large-scale deployments, such as building large replicated databases running on server farms. Thus, WebScaleSQL opened a path toward deduplicating the efforts each company had been putting into maintaining its own branch of MySQL, and toward bringing together more developers. By combining the efforts of these companies and incorporating various changes and new features into MySQL, WebScaleSQL aimed at supporting the deployment of MySQL in large-scale environments. The project's source code is licensed under version 2 of the GNU General Public License, and is hosted on GitHub.
1 2 Prior to MySQL 5.5.3, UTF-8 and UCS-2 encoded strings are limited to the BMP; MySQL 5.5.3 and later use utf8mb4 for full Unicode support.
↑ Initially, it was a MyISAM-only feature; supported by InnoDB since the release of MySQL 5.6.
↑ In MySQL 5.0, storage engines must be compiled in; since MySQL 5.1, storage engines can be dynamically loaded at run time.
Related Research Articles
Ulf Michael Widenius is the main author of the original version of the open source MySQL database, a founding member of the MySQL AB company and CTO of the MariaDB Corporation AB. Additionally, he is a founder and general partner at venture capital firm OpenOcean.
The following tables compare general and technical information for a number of relational database management systems. Please see the individual products' articles for further information. Unless otherwise specified in footnotes, comparisons are based on the stable versions without any add-ons, extensions or external programs.
InnoDB is a storage engine for the database management system MySQL. Since the release of MySQL 5.5.5 in 2010, it replaced MyISAM as MySQL's default table type. It provides the standard ACID-compliant transaction features, along with foreign key support. It is included as standard in most binaries distributed by MySQL AB, the exception being some OEM versions.
Innobase Oy was a Finnish company headquartered in Helsinki, Finland. Innobase is best known for being the developer of the InnoDB transactional storage engine for the MySQL open source database system. From 2005 on, Innobase Oy was a subsidiary of Oracle Corporation, which acquired Innobase. It has been fully merged into Oracle and terminated all business activities as of July 8, 2013.
MyISAM was the default storage engine for the MySQL relational database management system versions prior to 5.5 released in December 2009. It is based on the older ISAM code, but it has many useful extensions.
MySQL Workbench is a visual database design tool that integrates SQL development, administration, database design, creation and maintenance into a single integrated development environment for the MySQL database system. It is the successor to DBDesigner 4 from fabFORCE.net, and replaces the previous package of software, MySQL GUI Tools Bundle.
Zmanda Recovery Manager is a perl-based utility used to automate backup and recovery of MySQL databases. It is released under the GNU General Public License.
Falcon was a transactional storage engine being developed for the MySQL relational database management system. Development was stopped after Oracle purchased MySQL. It was based on the Netfrastructure database engine. Falcon was designed to take advantage of Sun's zfs file system.
An embedded database system is a database management system (DBMS) which is tightly integrated with an application software that requires access to stored data, such that the database system is "hidden" from the application’s end-user and requires little or no ongoing maintenance. It is actually a broad technology category that includes
Aria is a storage engine for the MariaDB and MySQL relational database management systems. Its goal is to make a crash-safe alternative to MyISAM. It is not yet transactional but plans to add proper support for database transactions at some point in the future. The long-term goal is for Aria to be the default transactional and non-transactional storage engine for MariaDB. It has been in development since 2007 and was first announced by Michael "Monty" Widenius on his blog. Aria is used for internal temporary tables in MariaDB, a community-developed branch of the MySQL database led by Widenius. Aria is not shipped with MySQL or Percona Server, but is included in the TokuDB release of MariaDB.
Drizzle is an abandoned free software/open-source relational database management system (DBMS) that was forked from the now-defunct 6.0 development branch of the MySQL DBMS.
MariaDB is a community-developed, commercially supported fork of the MySQL relational database management system (RDBMS), intended to remain free and open-source software under the GNU General Public License. Development is led by some of the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle Corporation in 2009.
In relational databases a virtual column is a table column whose value is automatically computed using other columns values, or another deterministic expression. Virtual columns are defined of SQL:2003 as Generated Column, and are only implemented by some DBMSs, like MariaDB, SQL Server, Oracle and Firebird.
Percona Server for MySQL is a distribution of the MySQL relational database management system created by Percona.
WebScaleSQL was an open-source relational database management system (RDBMS) created as a software branch of the production-ready community releases of MySQL. By joining efforts of a few companies and incorporating various changes and new features into MySQL, WebScaleSQL aimed toward fulfilling various needs arising from the deployment of MySQL in large-scale environments, which involve large amounts of data and numerous database servers.
Amazon Aurora is a relational database service developed and offered by Amazon Web Services beginning in October 2014. Aurora is available as part of the Amazon Relational Database Service (RDS).
Percona XtraDB is a storage engine for the MariaDB and Percona Server databases, and is intended as a drop-in replacement to InnoDB, which is one of the default engines available on the MySQL database.
The following outline is provided as an overview of and topical guide to MySQL:
MyRocks is open-source software developed at Facebook in order to use MySQL features with RocksDB implementations. It is based on Oracle MySQL 5.6.