In computing, a data warehouse known as an enterprise data warehouse, is a system used for reporting and data analysis, is considered a core component of business intelligence. DWs are central repositories of integrated data from one or more disparate sources, they store current and historical data in one single place that are used for creating analytical reports for workers throughout the enterprise. The data stored in the warehouse is uploaded from the operational systems; the data may pass through an operational data store and may require data cleansing for additional operations to ensure data quality before it is used in the DW for reporting. The typical extract, load -based data warehouse uses staging, data integration, access layers to house its key functions; the staging layer or staging database stores raw data extracted from each of the disparate source data systems. The integration layer integrates the disparate data sets by transforming the data from the staging layer storing this transformed data in an operational data store database.
The integrated data are moved to yet another database called the data warehouse database, where the data is arranged into hierarchical groups called dimensions, into facts and aggregate facts. The combination of facts and dimensions is sometimes called a star schema; the access layer helps users retrieve data. The main source of the data is cleansed, transformed and made available for use by managers and other business professionals for data mining, online analytical processing, market research and decision support. However, the means to retrieve and analyze data, to extract and load data, to manage the data dictionary are considered essential components of a data warehousing system. Many references to data warehousing use this broader context. Thus, an expanded definition for data warehousing includes business intelligence tools, tools to extract and load data into the repository, tools to manage and retrieve metadata. A data warehouse maintains a copy of information from the source transaction systems.
This architectural complexity provides the opportunity to: Integrate data from multiple sources into a single database and data model. More congregation of data to single database so a single query engine can be used to present data in an ODS. Mitigate the problem of database isolation level lock contention in transaction processing systems caused by attempts to run large, long-running, analysis queries in transaction processing databases. Maintain data history if the source transaction systems do not. Integrate data from multiple source systems, enabling a central view across the enterprise; this benefit is always valuable, but so when the organization has grown by merger. Improve data quality, by providing consistent codes and descriptions, flagging or fixing bad data. Present the organization's information consistently. Provide a single common data model for all data of interest regardless of the data's source. Restructure the data so that it makes sense to the business users. Restructure the data so that it delivers excellent query performance for complex analytic queries, without impacting the operational systems.
Add value to operational business applications, notably customer relationship management systems. Make decision–support queries easier to write. Organize and disambiguate repetitive data The environment for data warehouses and marts includes the following: Source systems that provide data to the warehouse or mart. In regards to source systems listed above, R. Kelly Rainer states, "A common source for the data in data warehouses is the company's operational databases, which can be relational databases". Regarding data integration, Rainer states, "It is necessary to extract data from source systems, transform them, load them into a data mart or warehouse". Rainer discusses storing data in an organization's data warehouse or data marts. Metadata are data about data. "IT personnel need information about data sources. Today, the most successful companies are those that can respond and flexibly to market changes and opportunities. A key to this response is the effective and efficient use of data and information by analysts and managers.
A "data warehouse" is a repository of historical data that are organized by subject to support decision makers in the organization. Once data are stored in a data mart or warehouse, they can be accessed. A data mart is a simple form of a data warehouse, focused on a single subject, hence they draw data from a limited number of sources such as sales, finance or marketing. Data marts are built and controlled by a single department within an organization; the sources could be a central data warehouse, or external data. Denormalization is the norm for data modeling techniques in this system. Given that data marts cover only a subset of the data contained in a data warehouse, they are easier and faster to implement. Types of data marts include dependent and hybrid data marts. Online analytical processing is characterized by a low volume of transactions. Queries are very complex and involve aggregations. For OLAP systems, response time is an effectiveness measure
Relational database management system
A relational database management system is a database management system based on the relational model of data. Most databases in widespread use today are based on this model. RDBMSs have been a common option for the storage of information in databases used for financial records and logistical information, personnel data, other applications since the 1980s. Relational databases have replaced legacy hierarchical databases and network databases, because RDBMS were easier to implement and administer. Nonetheless, relational databases received continued, unsuccessful challenges by object database management systems in the 1980s and 1990s, as well as by XML database management systems in the 1990s. However, due to the expanse of technologies, such as horizontal scaling of computer clusters, NoSQL databases have become popular as an alternative to RDBMS databases. According to DB-Engines, in June 2018, the most used systems were Oracle, MySQL, Microsoft SQL Server, PostgreSQL, IBM DB2, Microsoft Access, SQLite.
According to research company Gartner, in 2011, the five leading Proprietary software relational database vendors by revenue were Oracle, IBM, Microsoft, SAP including Sybase, Teradata. In 1974, IBM began developing System R, a research project to develop a prototype RDBMS. However, the first commercially available RDBMS was Oracle, released in 1979 by Relational Software, now Oracle Corporation. Other examples of an RDBMS include DB2, SAP Sybase ASE, Informix. In 1984, the first RDBMS for Macintosh began being developed, code-named Silver Surfer, it was released in 1987 as 4th Dimension and known today as 4D; the term "relational database" was invented by E. F. Codd at IBM in 1970. Codd introduced the term in his research paper "A Relational Model of Data for Large Shared Data Banks". In this paper and papers, he defined what he meant by "relational". One well-known definition of what constitutes a relational database system is composed of Codd's 12 rules. However, no commercial implementations of the relational model conform to all of Codd's rules, so the term has come to describe a broader class of database systems, which at a minimum: Present the data to the user as relations.
The first systems that were faithful implementations of the relational model were from: University of Michigan -- Micro DBMS Massachusetts Institute of Technology IBM UK Scientific Centre at Peterlee -- IS1 and its successor, PRTV The first system sold as an RDBMS was Multics Relational Data Store. Ingres and IBM BS12 followed; the most definition of an RDBMS is a product that presents a view of data as a collection of rows and columns if it is not based upon relational theory. By this definition, RDBMS products implement some but not all of Codd's 12 rules. A second school of thought argues that if a database does not implement all of Codd's rules, it is not relational; this view, shared by many theorists and other strict adherents to Codd's principles, would disqualify most DBMSs as not relational. For clarification, they refer to some RDBMSs as truly-relational database management systems, naming others pseudo-relational database management systems; as of 2009, most commercial relational DBMSs employ SQL as their query language.
Alternative query languages have been proposed and implemented, notably the pre-1996 implementation of Ingres QUEL. SQL Object database Online analytical processing and ROLAP Data warehouse Star schema Snowflake schema List of relational database management systems Comparison of relational database management systems
Concurrency (computer science)
In computer science, concurrency refers to the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the final outcome. This allows for parallel execution of the concurrent units, which can improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability property of a program, algorithm, or problem into order-independent or partially-ordered components or units. A number of mathematical models have been developed for general concurrent computation including Petri nets, process calculi, the parallel random-access machine model, the actor model and the Reo Coordination Language; as Leslie Lamport notes, "While concurrent program execution had been considered for years, the computer science of concurrency began with Edsger Dijkstra's seminal 1965 paper that introduced the mutual exclusion problem.... The ensuing decades have seen a huge growth of interest in concurrency—particularly in distributed systems.
Looking back at the origins of the field, what stands out is the fundamental role played by Edsger Dijkstra". Because computations in a concurrent system can interact with each other while being executed, the number of possible execution paths in the system can be large, the resulting outcome can be indeterminate. Concurrent use of shared resources can be a source of indeterminacy leading to issues such as deadlocks, resource starvation. Design of concurrent systems entails finding reliable techniques for coordinating their execution, data exchange, memory allocation, execution scheduling to minimize response time and maximise throughput. Concurrency theory has been an active field of research in theoretical computer science. One of the first proposals was Carl Adam Petri's seminal work on Petri nets in the early 1960s. In the years since, a wide variety of formalisms have been developed for modeling and reasoning about concurrency. A number of formalisms for modeling and understanding concurrent systems have been developed, including: The parallel random-access machine The actor model Computational bridging models such as the bulk synchronous parallel model Petri nets Process calculi Calculus of communicating systems Communicating sequential processes model π-calculus Tuple spaces, e.g. Linda Simple Concurrent Object-Oriented Programming Reo Coordination LanguageSome of these models of concurrency are intended to support reasoning and specification, while others can be used through the entire development cycle, including design, proof and simulation of concurrent systems.
Some of these are based on message passing. The proliferation of different models of concurrency has motivated some researchers to develop ways to unify these different theoretical models. For example and Sangiovanni-Vincentelli have demonstrated that a so-called "tagged-signal" model can be used to provide a common framework for defining the denotational semantics of a variety of different models of concurrency, while Nielsen and Winskel have demonstrated that category theory can be used to provide a similar unified understanding of different models; the Concurrency Representation Theorem in the actor model provides a general way to represent concurrent systems that are closed in the sense that they do not receive communications from outside. The mathematical denotation denoted by a closed system S is constructed better approximations from an initial behavior called ⊥S using a behavior approximating function progressionS to construct a denotation for S as follows: DenoteS ≡ ⊔i∈ω progressionSiIn this way, S can be mathematically characterized in terms of all its possible behaviors.
Various types of temporal logic can be used to help reason about concurrent systems. Some of these logics, such as linear temporal logic and computation tree logic, allow assertions to be made about the sequences of states that a concurrent system can pass through. Others, such as action computational tree logic, Hennessy–Milner logic, Lamport's temporal logic of actions, build their assertions from sequences of actions; the principal application of these logics is in writing specifications for concurrent systems. Concurrent programming encompasses programming languages and algorithms used to implement concurrent systems. Concurrent programming is considered to be more general than parallel programming because it can involve arbitrary and dynamic patterns of communication and interaction, whereas parallel systems have a predefined and well-structured communications pattern; the base goals of concurrent programming include correctness and robustness. Concurrent systems such as Operating systems and Database management systems are designed to operate indefinitely, including automatic recovery from failure, not terminate unexpectedly.
Some concurrent systems implement a form of transparent concurrency, in which concurrent computational entities may compete for and share a single resource, but the complexities of this competition and sharing are shielded from the programmer. Because they use shared resources, concurrent systems in general require the inclusion of some kind of arbiter somewhere in their implementation, to control access to those resources; the use of arbiters introduces the possibility of indeterminacy in concurrent computation which has major implications for practice including correctness and performance
Oracle Corporation is an American multinational computer technology corporation headquartered in Redwood Shores, California. The company specializes in developing and marketing database software and technology, cloud engineered systems, enterprise software products — its own brands of database management systems. In 2018, Oracle was the third-largest software maker by revenue, after Alphabet; the company develops and builds tools for database development and systems of middle-tier software, enterprise resource planning software, customer relationship management software, supply chain management software. Larry Ellison co-founded Oracle Corporation in 1977 with Bob Miner and Ed Oates under the name Software Development Laboratories. Ellison took inspiration from the 1970 paper written by Edgar F. Codd on relational database management systems named "A Relational Model of Data for Large Shared Data Banks." He heard about the IBM System R database from an article in the IBM Research Journal provided by Oates.
Ellison wanted to make Oracle's product compatible with System R, but failed to do so as IBM kept the error codes for their DBMS a secret. SDL changed its name to Relational Software, Inc in 1979 again to Oracle Systems Corporation in 1982, to align itself more with its flagship product Oracle Database. At this stage Bob Miner served as the company's senior programmer. On March 12, 1986, the company had its initial public offering. In 1995, Oracle Systems Corporation changed its name to Oracle Corporation named Oracle, but sometimes referred to as Oracle Corporation, the name of the holding company. Part of Oracle Corporation's early success arose from using the C programming language to implement its products; this eased porting to different operating systems. 1979: offers the first commercial SQL RDBMS 1983: offers a VAX-mode database 1984: offers the first database with read-consistency 1986: offers a client-server DBMS 1987: introduces UNIX-based Oracle applications 1988: introduces PL/SQL.
1992: offers full applications implementation methodology 1995: offers the first 64-bit RDBMS 1996: moves towards an open standards-based, web-enabled architecture 1999: offers its first DBMS with XML support 2001: becomes the first to complete 3 terabyte TPC-H world record 2002: offers the first database to pass 15 industry standard security evaluations 2003: introduces what it calls "Enterprise Grid Computing" with Oracle10g 2005: releases its first free database, Oracle Database 10g Express Edition 2006: acquires Siebel Systems 2007: acquires Hyperion Solutions 2008: Smart scans in software improve query-response in HP Oracle Database Machine / Exadata storage 2010: acquires Sun Microsystems 2013: begins use of Oracle 12c, capable of providing cloud services with Oracle Database 2014: acquires Micros Systems 2016: acquires NetSuite Inc. Oracle ranked No. 82 in the 2018 Fortune 500 list of the largest United States corporations by total revenue. According to Bloomberg, Oracle's CEO-to-employee pay ratio is 1,205:1.
The CEO's compensation in 2017 was $108,295,023. Meanwhile, the median employee compensation rate was $89,887. Oracle designs and sells both software and hardware products, as well as offering services that complement them. Many of the products have been added to Oracle's portfolio through acquisitions. Oracle's E-delivery service provides documentation. Oracle Database Release 10: In 2004, Oracle Corporation shipped release 10g as the latest version of Oracle Database. Release 11: Release 11g became the current Oracle Database version in 2007. Oracle Corporation released Oracle Database 11g Release 2 in September 2009; this version was available in four commercial editions—Enterprise Edition, Standard Edition, Standard Edition One, Personal Edition—and in one free edition—the Express Edition. The licensing of these editions shows various restrictions and obligations that were called complex by licensing expert Freirich Florea; the Enterprise Edition, the most expensive of the Database Editions, has the fewest restrictions — but has complex licensing.
Oracle Corporation constrains the Standard Edition and Standard Edition One with more licensing restrictions, in accordance with their lower price. Release 12: Release 12c became available on July 1, 2013. Oracle Corporation has acquired and developed the following additional database technologies: Berkeley DB, which offers embedded database processing Oracle Rdb, a relational database system running on OpenVMS platforms. Oracle acquired Rdb in 1994 from Digital Equipment Corporation. Oracle has since made many enhancements to this product and development continues as of 2008. TimesTen, which features in-memory database operations Oracle Essbase, which continues the Hyperion Essbase tradition of multi-dimensional database management MySQL, a relational database management system licensed under the GNU General Public License developed by MySQL AB Oracle NoSQL Database, a scalable, distributed key-value NoSQL database Oracle Fusion Middleware is a family of middleware
GNU General Public License
The GNU General Public License is a widely-used free software license, which guarantees end users the freedom to run, study and modify the software. The license was written by Richard Stallman of the Free Software Foundation for the GNU Project, grants the recipients of a computer program the rights of the Free Software Definition; the GPL is a copyleft license, which means that derivative work can only be distributed under the same license terms. This is in distinction to permissive free software licenses, of which the BSD licenses and the MIT License are widely-used examples. GPL was the first copyleft license for general use; the GPL license family has been one of the most popular software licenses in the free and open-source software domain. Prominent free-software programs licensed under the GPL include the Linux kernel and the GNU Compiler Collection. David A. Wheeler argues that the copyleft provided by the GPL was crucial to the success of Linux-based systems, giving the programmers who contributed to the kernel the assurance that their work would benefit the whole world and remain free, rather than being exploited by software companies that would not have to give anything back to the community.
In 2007, the third version of the license was released to address some perceived problems with the second version that were discovered during its long-time usage. To keep the license up to date, the GPL license includes an optional "any version" clause, allowing users to choose between the original terms or the terms in new versions as updated by the FSF. Developers can omit it; the GPL was written by Richard Stallman in 1989, for use with programs released as part of the GNU project. The original GPL was based on a unification of similar licenses used for early versions of GNU Emacs, the GNU Debugger and the GNU C Compiler; these licenses contained similar provisions to the modern GPL, but were specific to each program, rendering them incompatible, despite being the same license. Stallman's goal was to produce one license that could be used for any project, thus making it possible for many projects to share code; the second version of the license, version 2, was released in 1991. Over the following 15 years, members of the free software community became concerned over problems in the GPLv2 license that could let someone exploit GPL-licensed software in ways contrary to the license's intent.
These problems included tivoization, compatibility issues similar to those of the Affero General Public License—and patent deals between Microsoft and distributors of free and open-source software, which some viewed as an attempt to use patents as a weapon against the free software community. Version 3 was developed to attempt to address these concerns and was released on 29 June 2007. Version 1 of the GNU GPL, released on 25 February 1989, prevented what were the two main ways that software distributors restricted the freedoms that define free software; the first problem was that distributors may publish binary files only—executable, but not readable or modifiable by humans. To prevent this, GPLv1 stated that copying and distributing copies or any portion of the program must make the human-readable source code available under the same licensing terms; the second problem was that distributors might add restrictions, either to the license, or by combining the software with other software that had other restrictions on distribution.
The union of two sets of restrictions would apply to the combined work, thus adding unacceptable restrictions. To prevent this, GPLv1 stated that modified versions, as a whole, had to be distributed under the terms in GPLv1. Therefore, software distributed under the terms of GPLv1 could be combined with software under more permissive terms, as this would not change the terms under which the whole could be distributed. However, software distributed under GPLv1 could not be combined with software distributed under a more restrictive license, as this would conflict with the requirement that the whole be distributable under the terms of GPLv1. According to Richard Stallman, the major change in GPLv2 was the "Liberty or Death" clause, as he calls it – Section 7; the section says that licensees may distribute a GPL-covered work only if they can satisfy all of the license's obligations, despite any other legal obligations they might have. In other words, the obligations of the license may not be severed due to conflicting obligations.
This provision is intended to discourage any party from using a patent infringement claim or other litigation to impair users' freedom under the license. By 1990, it was becoming apparent that a less restrictive license would be strategically useful for the C library and for software libraries that did the job of existing proprietary ones; the version numbers diverged in 1999 when version 2.1 of the LGPL was released, which renamed it the GNU Lesser General Public License to reflect its place in the philosophy. Most "GPLv2 or any version" is stated by users of the license, to allow upgrading to GPLv3. In late 2005, the Free Software Foundation announced work on version 3 of the GPL. On 16 January 2006, the first "discussion draft" of GPLv3 was published, the public consultation began; the public consultation was planned for ni
MySQL is an open-source relational database management system. Its name is a combination of "My", the name of co-founder Michael Widenius's daughter, "SQL", the abbreviation for Structured Query Language. MySQL is free and open-source software under the terms of the GNU General Public License, is available under a variety of proprietary licenses. MySQL was owned and sponsored by the Swedish company MySQL AB, bought by Sun Microsystems. In 2010, when Oracle acquired Sun, Widenius forked the open-source MySQL project to create MariaDB. MySQL is a component of the LAMP web application software stack, an acronym for Linux, Apache, MySQL, Perl/PHP/Python. MySQL is used by many database-driven web applications, including Drupal, phpBB, WordPress. MySQL is used by many popular websites, including Facebook, Twitter and YouTube. MySQL is written in C and C++, its SQL parser is written in yacc. MySQL works on many system platforms, including AIX, BSDi, FreeBSD, HP-UX, eComStation, i5/OS, IRIX, macOS, Microsoft Windows, NetBSD, Novell NetWare, OpenBSD, OpenSolaris, OS/2 Warp, QNX, Oracle Solaris, SunOS, SCO OpenServer, SCO UnixWare and Tru64.
A port of MySQL to OpenVMS exists. The MySQL server software itself and the client libraries use dual-licensing distribution, they are offered under a proprietary license. Support can be obtained from the official manual. Free support additionally is available in different IRC forums. Oracle offers paid support via its MySQL Enterprise products, they differ in price. Additionally, a number of third party organisations exist to provide support and services, including MariaDB and Percona. MySQL has received positive reviews, reviewers noticed it "performs well in the average case" and that the "developer interfaces are there, the documentation is very good", it has been tested to be a "fast 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 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 mSQL antecedent. 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. Version 4.01: beta from August 2003, Jyoti adopts MySQL for database tracking Version 4.1: beta from June 2004, production release October 2004. Version 5.0: beta from March 2005, production release October 2005. 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 in 2008. Version 5.1: production release 27 November 2008 Version 5.1 contained 20 known crashing and wrong result bugs in addition to the 35 present in version 5.0. MySQL 5.1 and 6.0-alpha showed poor performance when used for data warehousing – due to its inability to utilize multiple CPU cores for processing a single query. Oracle acquired Sun Microsystems on 27 January 2010; the day Oracle announced the purchase of Sun, Michael "Monty" Widenius forked MySQL, launching MariaDB, took a swath of MySQL developers with him. MySQL Server 5.5 was available. Enhancements and features include: The default storage engine is InnoDB, which supports transactions and referential integrity constraints. Improved InnoDB I/O subsystem Improved SMP support Semisynchronous replication. SIGNAL and RESIGNAL statement in compliance with the SQL standard. Support for supplementary Unicode character sets utf16, utf32, utf8mb4.
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 MySQL 5.6 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 large tables, TIMESTAMP column type that stores milliseconds, improvements to replication, better performance monitoring by expanding the data available through the PERFORMANCE_SCHEMA; the InnoDB storage engine included support for full-text search and improved group commit performance. The general availability of MySQL 5.7 was a
MariaDB is a community-developed, commercially supported fork of the MySQL relational database management system, 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. MariaDB intends to maintain high compatibility with MySQL, ensuring a drop-in replacement capability with library binary parity and exact matching with MySQL APIs and commands, it includes a new storage engine, Aria, an alternative to MyISAM that intends to be the default transactional and non-transactional engine. It used XtraDB as the default storage engine, switched back to InnoDB since version 10.2. Its lead developer is Michael "Monty" Widenius, one of the founders of MySQL AB and the founder of Monty Program AB. On 16 January 2008, MySQL AB announced that it had agreed to be acquired by Sun Microsystems for $1 billion; the acquisition completed on 26 February 2008.
MariaDB is named after Monty's younger daughter Maria, similar to how MySQL is named after his other daughter My. MariaDB version numbers follow the MySQL's numbering scheme up to version 5.5. Thus, MariaDB 5.5 offers all of the MySQL 5.5 features. There exists a gap in MySQL versions between 5.1 and 5.5, while MariaDB issued 5.2 and 5.3 point releases. Since specific new features have been developed in MariaDB, the developers decided that a major version number change was necessary. MariaDB has been supported in Amazon RDS service since October 2015. MariaDB is a supported database in Microsoft Azure. MariaDB's API and protocol are compatible with those used by MySQL, plus some features to support native non-blocking operations and progress reporting; this means that all connectors and applications which work with MySQL should work on MariaDB—whether or not they support its native features. On this basis, Fedora developers replaced MySQL with MariaDB in Fedora 19, out of concerns that Oracle was making MySQL a more closed software project.
OpenBSD in April 2013 dropped MySQL for MariaDB 5.5. In December 2012 Michael Widenius, David Axmark, Allan Larsson announced the formation of a foundation that would oversee the development of MariaDB. In April 2013 the Foundation announced that it had appointed Simon Phipps as its Secretary and interim Chief Executive Officer, Rasmus Johansson as Chairman of the Board, Andrew Katz, Jeremy Zawodny, Michael Widenius as Board members. Noting that it wished to create a governance model similar to that used by the Eclipse Foundation, the Board appointed the Eclipse Foundation's Executive Director Mike Milinkovich as an advisor to lead the transition. SkySQL Corporation Ab, a company formed by ex-MySQL executives and investors after Oracle bought MySQL, announced in April 2013 that they were merging their company with Monty Program AB, joining the MariaDB Foundation; the MariaDB Foundation appointed Widenius as its CTO. Simon Phipps quit in 2014 on the sale of the MariaDB trademark to SkySQL, he said: "I quit as soon as it was obvious the company was not going to allow an independent foundation."
On 1 October 2014, SkySQL Corporation AB changed its name to MariaDB Corporation AB to reflect its role as the main driving force behind the development of MariaDB server and the biggest support-provider for it. MariaDB is a registered trademark of MariaDB Corporation AB, used under license by the MariaDB Foundation. From January 2015 to September 2018, Otto Kekäläinen was the CEO of the MariaDB Foundation, he stepped down on 1 October of that year. Arjen Lentz was appointed CEO of the Foundation in October 2018, but resigned in December 2018. Kaj Arnö joined as the CEO on 1 February 2019. Eric Herman is the current Chairman of the Board. MariaDB is used at ServiceNow, DBS Bank, Google and the Wikimedia Foundation since 2013. Several Linux and BSD distributions include MariaDB, like Ubuntu; some default to MariaDB, such as Arch Linux, Debian, Red Hat Enterprise Linux, CentOS, openSUSE, SUSE Linux Enterprise Server, OpenBSD, FreeBSD. In 2013 Google tasked one of its engineers to work at the MariaDB Foundation.
A group of investment companies led by Intel has invested $20 million in SkySQL. The European Investment Bank has funded MariaDB with €25 million in 2017. Comparison of relational database management systems Multi-master replication Bartholomew, Daniel. Getting Started with MariaDB. ISBN 9781782168096. Bartholomew, Daniel. MariaDB Cookbook. ISBN 978-1-78328-440-5. Forta, Ben. MariaDB Crash Course. Addison Wesley. ISBN 0-321-79994-1. MariaDB Foundation website MariaDB Corporation website MariaDB, the Backward Compatible Branch of MySQL Database Server on YouTube – a lecture given by Monty Widenius at Google