A database is an organized collection of data stored and accessed electronically from a computer system. Where databases are more complex they are developed using formal design and modeling techniques; the database management system is the software that interacts with end users and the database itself to capture and analyze the data. The DBMS software additionally encompasses; the sum total of the database, the DBMS and the associated applications can be referred to as a "database system". The term "database" is used to loosely refer to any of the DBMS, the database system or an application associated with the database. Computer scientists may classify database-management systems according to the database models that they support. Relational databases became dominant in the 1980s; these model data as rows and columns in a series of tables, the vast majority use SQL for writing and querying data. In the 2000s, non-relational databases became popular, referred to as NoSQL because they use different query languages.
Formally, a "database" refers to the way it is organized. Access to this data is provided by a "database management system" consisting of an integrated set of computer software that allows users to interact with one or more databases and provides access to all of the data contained in the database; the DBMS provides various functions that allow entry and retrieval of large quantities of information and provides ways to manage how that information is organized. Because of the close relationship between them, the term "database" is used casually to refer to both a database and the DBMS used to manipulate it. Outside the world of professional information technology, the term database is used to refer to any collection of related data as size and usage requirements necessitate use of a database management system. Existing DBMSs provide various functions that allow management of a database and its data which can be classified into four main functional groups: Data definition – Creation and removal of definitions that define the organization of the data.
Update – Insertion and deletion of the actual data. Retrieval – Providing information in a form directly usable or for further processing by other applications; the retrieved data may be made available in a form the same as it is stored in the database or in a new form obtained by altering or combining existing data from the database. Administration – Registering and monitoring users, enforcing data security, monitoring performance, maintaining data integrity, dealing with concurrency control, recovering information, corrupted by some event such as an unexpected system failure. Both a database and its DBMS conform to the principles of a particular database model. "Database system" refers collectively to the database model, database management system, database. Physically, database servers are dedicated computers that hold the actual databases and run only the DBMS and related software. Database servers are multiprocessor computers, with generous memory and RAID disk arrays used for stable storage.
RAID is used for recovery of data. Hardware database accelerators, connected to one or more servers via a high-speed channel, are used in large volume transaction processing environments. DBMSs are found at the heart of most database applications. DBMSs may be built around a custom multitasking kernel with built-in networking support, but modern DBMSs rely on a standard operating system to provide these functions. Since DBMSs comprise a significant market and storage vendors take into account DBMS requirements in their own development plans. Databases and DBMSs can be categorized according to the database model that they support, the type of computer they run on, the query language used to access the database, their internal engineering, which affects performance, scalability and security; the sizes and performance of databases and their respective DBMSs have grown in orders of magnitude. These performance increases were enabled by the technology progress in the areas of processors, computer memory, computer storage, computer networks.
The development of database technology can be divided into three eras based on data model or structure: navigational, SQL/relational, post-relational. The two main early navigational data models were the hierarchical model and the CODASYL model The relational model, first proposed in 1970 by Edgar F. Codd, departed from this tradition by insisting that applications should search for data by content, rather than by following links; the relational model employs sets of ledger-style tables, each used for a different type of entity. Only in the mid-1980s did computing hardware become powerful enough to allow the wide deployment of relational systems. By the early 1990s, relational systems dominated in all large-scale data processing applications, as of 2018 they remain dominant: IBM DB2, Oracle, MySQL, Microsoft SQL Server are the most searched DBMS; the dominant database language, standardised SQL for the relational model, has influenced database languages for other data models. Object databases were developed in the 1980s to overcome the inconvenience of object-relational impedance mismatch, which led to the coining of the term "post-relational" and the development of hybrid object-relational databas
Honeywell International Inc. is an American multinational conglomerate company that makes a variety of commercial and consumer products, engineering services and aerospace systems for a wide variety of customers, from private consumers to major corporations and governments. The company operates four business units, known as Strategic Business Units – Honeywell Aerospace and Building Technologies and Productivity Solutions, Honeywell Performance Materials and Technologies. Honeywell is a Fortune 100 company. In 2018, Honeywell ranked 77th in the Fortune 500. Honeywell has a global workforce of 130,000, of whom 58,000 are employed in the United States; the company is headquartered in New Jersey. Its current chief executive officer is Darius Adamczyk; the company and its corporate predecessors were part of the Dow Jones Industrial Average Index from December 7, 1925 until February 9, 2008. The company's current name, Honeywell International Inc. is the product of a merger in which Honeywell Inc. was acquired by the much larger AlliedSignal in 1999.
The company headquarters were consolidated with AlliedSignal's headquarters in Morristown, New Jersey. In 2015, the headquarters were moved to Morris Plains. On November 30, 2018, Honeywell announced that its corporate headquarters would be moved to Charlotte. Honeywell has many brands that commercial and retail consumers may recognize, including its line of home thermostats and Garrett turbochargers. In addition to consumer home products, Honeywell itself produces thermostats, security alarm systems, air cleaners and dehumidifiers; the company licenses its brand name for use in various retail products made by partner manufacturers, including air conditioners, fans, security safes, home generators, paper shredders. Although Mark Honeywell’s Heating Specialty Company was not established until 1906, today’s Honeywell traces its roots back to 1885 when the Swiss-born Albert Butz invented the damper-flapper, a thermostat for coal furnaces, to automatically regulate heating systems; the following year he founded the Butz Thermo-Electric Regulator Company.
In 1888, after a falling out with his investors, Butz left the company and transferred the patents to the legal firm Paul and Merwin, who renamed the company the Consolidated Temperature Controlling Company. As the years passed, CTCC struggled with growing debts, they underwent several name changes in an attempt to keep the business afloat. After the company was renamed to the Electric Heat Regulator Company in 1893, W. R. Sweatt, a stockholder in the company, was sold "an extensive list of patents" and named secretary-treasurer.:22 On February 23, 1898 he bought out the remaining shares of the company from the other stockholders. In 1906, Mark Honeywell founded the Honeywell Heating Specialty Company in Wabash, Indiana, to manufacture and market his invention, the mercury seal generator; as Honeywell’s company grew it began to clash with the renamed Minneapolis Heat Regulator Company. This led to the merging of both companies into the publicly held Minneapolis-Honeywell Regulator Company in 1927.
Honeywell was named the company's first president, alongside W. R. Sweatt as its first chairman. W. R. Sweatt and his son Harold provided 75 years of uninterrupted leadership for the company. W. R. Sweatt survived rough spots and turned an innovative idea – thermostatic heating control – into a thriving business. Harold, who took over in 1934, led Honeywell through a period of growth and global expansion that set the stage for Honeywell to become a global technology leader; the merger into the Minneapolis-Honeywell Regulator Company proved to be a saving grace for the corporation. The combined assets were valued at over $3.5 million, with less than $1 million in liabilities just months before Black Monday.:49 In 1931, Minneapolis-Honeywell began a period of expansion and acquisition when they purchased Time-O-Stat Controls Company, giving the company access to a greater number of patents to be used in their controls systems. 1934 marked Minneapolis-Honeywell’s first foray into the international market, when they acquired the Brown Instrument Company, inherited their relationship with the Yamatake Company of Tokyo, a Japan-based distributor.:51 Later that same year, Minneapolis-Honeywell would start distributorships across Canada, as well as one in the Netherlands, their first European office.
This expansion into international markets continued in 1936, with their first distributorship in London, as well as their first foreign assembly facility being established in Canada. By 1937, ten years after the merger, Minneapolis-Honeywell had over 3,000 employees, with $16 million in annual revenue. Having survived the Depression, Minneapolis-Honeywell was approached by the US military for engineering and manufacturing projects. In 1941, Minneapolis-Honeywell developed a superior tank periscope and camera stabilizers, as well as the C-1 autopilot; the C-1 revolutionized precision bombing in the war effort, was used on the two B-29 bombers that dropped atomic bombs on Japan in 1945. The success of these projects led Minneapolis-Honeywell to open an Aero division in Chicago on October 5, 1942.:73 This division was responsible for the development of the formation stick to control autopilots, more accurate gas gauges for planes, the turbo supercharger.:79 In 1950, Minneapolis-Honeywell’s Aero division was contracted for the controls on the first US nuclear submarine, USS Nautilus.:88 The following year, the company acquired Intervox Company for
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct computers and makes them appear to be a single computer; the development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine; when computers in a group work in cooperation, they form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. Embedded operating systems are designed to be used in embedded computer systems, they are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources, they are compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri
Multics is an influential early time-sharing operating system, based on the concept of a single-level memory. All modern operating systems were influenced by Multics – through Unix, created by some of the people who had worked on Multics – either directly or indirectly. Initial planning and development for Multics started in Cambridge, Massachusetts, it was a cooperative project led by MIT along with General Electric and Bell Labs. It was developed on the GE 645 computer, specially designed for it. Multics was conceived as a commercial product for General Electric, became one for Honeywell, albeit not successfully. Due to its many novel and valuable ideas, Multics had a significant impact on computer science despite its faults. Multics had numerous features intended to ensure high availability so that it would support a computing utility similar to the telephone and electricity utilities. Modular hardware structure and software architecture were used to achieve this; the system could grow in size by adding more of the appropriate resource, be it computing power, main memory, or disk storage.
Separate access control lists on every file provided flexible information sharing, but complete privacy when needed. Multics had a number of standard mechanisms to allow engineers to analyze the performance of the system, as well as a number of adaptive performance optimization mechanisms. Multics implemented a single-level store for data access, discarding the clear distinction between files and process memory; the memory of a process consisted of segments that were mapped into its address space. To read or write to them, the process used normal central processing unit instructions, the operating system took care of making sure that all the modifications were saved to disk. In POSIX terminology, it was. All memory in the system was part of some segment. One disadvantage of this was that the size of segments was limited to 256 kilowords, just over 1 MiB; this was due to the particular hardware architecture of the machines on which Multics ran, having a 36-bit word size and index registers of half that size.
Extra code had to be used to work on files larger than this, called multisegment files. In the days when one megabyte of memory was prohibitively expensive, before large databases and huge bitmap graphics, this limit was encountered. Another major new idea of Multics was dynamic linking, in which a running process could request that other segments be added to its address space, segments which could contain code that it could execute; this allowed applications to automatically use the latest version of any external routine they called, since those routines were kept in other segments, which were dynamically linked only when a process first tried to begin execution in them. Since different processes could use different search rules, different users could end up using different versions of external routines automatically. With the appropriate settings on the Multics security facilities, the code in the other segment could gain access to data structures maintained in a different process. Thus, to interact with an application running in part as a daemon, a user's process performed a normal procedure-call instruction to a code segment to which it had dynamically linked.
The code in that segment could modify data maintained and used in the daemon. When the action necessary to commence the request was completed, a simple procedure return instruction returned control of the user's process to the user's code; the single-level store and dynamic linking are still not available to their full power in other used operating systems, despite the rapid and enormous advance in the computer field since the 1960s. They are becoming more accepted and available in more limited forms, for example, dynamic linking. Multics supported aggressive on-line reconfiguration: central processing units, memory banks, disk drives, etc. could be added and removed while the system continued operating. At the MIT system, where most early software development was done, it was common practice to split the multiprocessor system into two separate systems during off-hours by incrementally removing enough components to form a second working system, leaving the rest still running the original logged-in users.
System software development testing could be done on the second system the components of the second system were added back to the main user system, without having shut it down. Multics supported multiple CPUs. Multics was the first major operating system. Despite this, early versions of Multics were broken into repeatedly; this led to further work that made the system much more secure and prefigured modern security engineering techniques. Break-ins became rare once the second-generation hardware base was adopted. Multics was the first operating system to provide a hierarchical file system, file names could be of alm
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