DBMS: Snapshot (Definitions)

"A snapshot is a view of information at a particular point in time." (Claudia Imhoff et al, "Mastering Data Warehouse Design", 2003)

"A database dump or the archiving of data out of a database as of some moment in time." (William H Inmon, "Building the Data Warehouse", 2005)

"A database snapshot is a moment-in-time recording of a database and keeps track of every change made to a database from the moment the snapshot was taken. This method often prevents user mistakes as an add-on to fault-tolerance." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A feature of SQL Server 2005 that enables you to indefinitely store the state of the database at a particular point in time." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A new feature of SQL Server 2005 where a snapshot of a database can be created at any given time to preserve the state of the database. The snapshot can be queried if desired and/or the entire database can be restored from the snapshot." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"The state of an object, a system, or a collection of attributes regarding a state at a particular point in time." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A read-only, static view of a database at the moment of snapshot creation." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A copy of a data structure at some point in time" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"A record of the current state of the database environment." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Physical Design (Definitions)

"The phase of a database design following the logical design that identifies the actual database tables and index structures used to implement the logical design." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed , 2002)

"The actual tables, columns, indexes, and other data structures used to store information in a SQL Server database. Development projects typically progress from a logical database design to a physical database design." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"The actual tables, columns, indexes, and other data structures used to store information in a SQL Server database. Development projects typically progress from a logical database design to a physical database design. See also logical design." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"The step in the database life cycle involved with the physical structure of the data; that is, how it will be stored, retrieved, and updated efficiently. In particular, it is concerned with issues of table indexing and data clustering on secondary storage devises (disk)." (Toby J Teorey, ", Database Modeling and Design 4th Ed", 2010)

"A stage of database design that maps the data storage and access characteristics of a database. Since these characteristics are a function of the types of devices supported by the hardware, the data access methods supported by the system (and the selected DBMS) physical design is both hardware- and software-dependent. See also physical model." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management 9th Ed", 2011)

"Physical design structures (PDSs) include items such as indexes, indexed VIEWs, and partitioning. These are referenced in the Database Engine Tuning Advisor, which is used to evaluate a database and can recommend the implementation of different types of physical design structures for better performance." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"States how the system will perform its functions, with actual physical specifications." (Linda Volonino & Efraim Turban, "Information Technology for Management 8th Ed", 2011)

DBMS: Graph Database (Definitions)

"Databases that use graph structures with nodes, edges and characteristics to depict and store information." (Swati V Chande, "Cloud Database Systems: NoSQL, NewSQL, and Hybrid", 2014)

"A graph database is any storage system that uses graph structures with nodes and edges, to represent and store data." (Jaroslav Pokorný, "Graph Databases: Their Power and Limitations", 2015)

"Makes use of graph structures with nodes and edges to manage and represent data. Unlike a relational database, a graph database does not rely on joins to connect data sources." (Judith S Hurwitz, "Cognitive Computing and Big Data Analytics", 2015)

"A database type that uses vertices and edges to store information." (Kornelije Rabuzin, "Query Languages for Graph Databases" 2018)

"A graph database is a database that uses graph structures for semantic queries with nodes, edges and properties to represent and store data." (Data Wold)

"A graph database is a type of database where there is no hierarchy - all data is stored as a series of nodes and edges (links between nodes). Typically each node of the graph represents a thing or the value of a property, and each edge represents a property - a particular type of relationship between the two nodes that it joins. This makes it easier to query the database based on relationships and it makes for a very flexible data structure that is easy to alter or extend. Graph databases are very useful for storing datasets that are complex with lots of connections." (Data.Gov.UK)

"Optimized database technology to store, manage, and access inter data to answer complex questions." (Forrester)

"A graph database, also called a graph-oriented database, is a type of NoSQL database that uses graph theory to store, map and query relationships." (The Open Group)

"they use graph structures (a finite set of ordered pairs or certain entities), with edges, properties and nodes for data storage. It provides index-free adjacency, meaning that every element is directly linked to its neighbour element." (Analytics Insight)

DBMS: Logical Design (Definitions)

 "An implementation-independent design that models the entities, relationships, and attributes in a database." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An implementation-independent design that models the entities, relationships, and attributes in a database." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"The phase of a database design concerned with identifying the relationships among the data elements. Contrast with Physical design." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"A part of database design that is concerned with modeling the business requirements and data." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"The abstract design and structure of your relational database." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"The abstract design and structure of your relational database. Focusing on the high-level objects and their interrelationships, this is usually generated during the analysis phase of most projects. It then serves as a guideline for creating the actual implementation of your SQL Server database." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"The steps in the database life cycle involved with the design of the conceptual data model (schema), schema integration, transformation to SQL tables, and table normalization; the design of a database in terms of how the data is related, but without regard to how it will be stored." (Toby J Teorey, ", Database Modeling and Design" 4th Ed., 2010)

"A stage in the design phase that matches the conceptual design to the requirements of the selected DBMS and is, therefore, software-dependent. It is used to translate the conceptual design into the internal model for a selected database management system, such as DB2, SQL Server, Oracle, IMS, Informix, Access, and Ingress." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

DBMS: Nondeterministic Function (Definitions)

"A function that may generate different outputs each time it is run, even if the inputs are always the same." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A function is non-deterministic if it can return different results when provided with the same input. The RAND function is non-deterministic because it returns a different randomly generated number each time it is called." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A characteristic of a function that means the function can return different results when provided with the same input. For example, the RAND function is nondeterministic because it returns a different randomly generated number each time it is called." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Nondeterministic functions return different values when they’re invoked with the same arguments." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Typically refers to functions such as nondeterministic functions. A nondeterministic function returns different results when called with the same input values. As an example, GETDATE() would return different results at different times. Indexed views can not include nondeterministic functions." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"An application whose state of execution cannot be predicted is said to be nondeterministic. Since the operating system schedules threads for execution on processor resources and there are too many factors that influence the OS scheduling, the state of execution of a concurrent application cannot be reliably predicted. Typically, incorrect use of nondeterminism in concurrent applications will be evidenced by the application returning different results from the same inputs." (Clay Breshears, "The Art of Concurrency", 2009)

"Exhibiting a lack of deterministic behavior, so results can vary from run to run of an algorithm. See more in the definition for deterministic." (Michael McCool et al, "Structured Parallel Programming", 2012)

"A user-defined function whose result is not solely dependent on the values of the input arguments. That is, successive invocation with the same argument value can produce a different answer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Deterministic Function (Definitions)

"A function that always generates the same outputs, given the same inputs." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A function is deterministic if it always returns the same output when presented with the same input." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A characteristic of a function that means the function always returns the same output when presented with the same input." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Deterministic functions return the same value each time they’re invoked with the same arguments." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Whether a function always returns the same output given the same inputs." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A deterministic function is one which, given a specific set of inputs, will always produce the same result. The SQL Server decryption functions are an example of deterministic functions. SQL Server’s symmetric encryption functions, however, generate a random IV so the result is nondeterministic." (Michael Coles & Rodney Landrum, , "Expert SQL Server 2008 Encryption", 2008)

"Typically refers to functions such as deterministic functions. A deterministic function always returns the same result when called with the same input values. Indexed VIEWs require any functions used within the indexed VIEW to be deterministic. As a comparison, see nondeterministic." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"a computation situation in which the execution time of an action sequence is known precisely." (Bruce P Douglass, "Real-Time Agility: The Harmony/ESW Method for Real-Time and Embedded Systems Development", 2009)

"Given the same inputs, a deterministic application will present the same (observable) results each and every time." (Clay Breshears, "The Art of Concurrency", 2009)

"A deterministic algorithm is an algorithm that behaves predictably. Given a particular input, a deterministic algorithm will always produce the same output. The definition of what is the “same” may be important due to limited precision in mathematical operations and the likelihood that optimizations including parallelization will rearrange the order of operations. These are often referred to as “rounding” differences, which result when the order of mathematical operations to compute answers differs between the original program and the final concurrent program. Concurrency is not the only factor that can lead to non-deterministic algorithms but in practice it is often the cause. Use of programming models with sequential semantics and eliminating data races with proper access controls will generally eliminate non-determinism other than the 'rounding' differences." (Michael McCool et al, "Structured Parallel Programming", 2012)

"Having a predictable value with a very narrow range of variance. As a result, deterministic values do not require the use of probability distributions to describe their behavior in business analysis methods or decisions and can usually be represented by a constant value." (Kenneth A Shaw, "Integrated Management of Processes and Information", 2013)

"A user-defined function with a result that is dependent on the values of the input arguments. Successive invocations with the same input values produce the same answer." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Database Catalog (Definitions)

"Tables provided in the Model database." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"The set of system tables in a database that describes the database contents." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database catalog contains the definition of all the objects in the database, as well as the definition of the database." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"This is an object in a database that is used to organize full-text indexes." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A directory storing metadata." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A group of schemas, usually composed of all schemas handled by a single DBMS." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"The part of a database that contains the definition of all the objects in the database, as well as the definition of the database." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Structured list made up of comparable objects, used as a reference." (Gilbert Raymond & Philippe Desfray, "Modeling Enterprise Architecture with TOGAF", 2014)

"A collection of tables and views that contains descriptions of objects such as tables, views, and indexes." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Database Objects (Definitions)

"One of the components of a database: table, view, index, procedure, trigger, column, default, or rule." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"One of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Any structure or entity that exists in an Oracle database, such as a table, index, PL/SQL program, or view. For a list of database objects owned by the current user, look in the data dictionary's USEROBJECTS view." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"Any database component. It could be a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure in a database." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"Any object in a database, such as a table, a view, an index, a stored procedure, or a trigger." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"An object that exists in an installation of a database system, such as an instance, a database, a database partition group, a buffer pool, a table, or an index." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Any of the various items included in a database including tables, views, diagrams, and so on." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

 

DBMS: Dirty Read (Definitions)

"Occurs when one transaction modifies a row, and then a second transaction reads that row before the first transaction commits the change. If the first transaction rolls back the change, the information read by the second transaction becomes invalid." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Reads that contain uncommitted data. For example, transaction 1 changes a row. Transaction 2 reads the changed row before transaction 1 commits the change. If transaction 1 rolls back the change, transaction 2 reads a row that is considered to have never existed." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A problem arising with concurrent transactions. The Dirty Read problem occurs when a transaction reads a row that has been changed but not committed by another transaction. The result is that Transaction #2's work is based on a change that never really happened. You can avoid Dirty Read by using an isolation level of READ COMMITTED or higher." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A problem with uncontrolled concurrent use of a database where a transaction acts on data that have been modified by an update transaction that hasn't committed and is later rolled back." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The problem that arises when a transaction reads the same data more than once, including data modified by concurrent transactions that are later rolled back." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A read that contains uncommitted data." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A read request that does not involve any locking mechanism. This means that data can be read that might later be rolled back resulting in an inconsistency between what was read and what is in the database." (IBM, "Informix Servers 12.1", 2014)

 "A transaction reads data that has been written by another transaction that has not been committed yet. Oracle Database never permits dirty reads." (Oracle)

"An operation that retrieves unreliable data, data that was updated by another transaction but not yet committed. It is only possible with the isolation level known as read uncommitted. This kind of operation does not adhere to the ACID principle of database design. It is considered very risky, because the data could be rolled back, or updated further before being committed; then, the transaction doing the dirty read would be using data that was never confirmed as accurate." (MySQL)

"Reads that contain uncommitted data." (Microsoft Technet)

DBMS: Trace (Definitions)

"The process of recording the sequence in which the statements in a program are executed and, optionally, the values of the program variables used in the statements." (Sybase, "Glossary", 2005)

"The SQL Profiler method for recording server events." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"This is a record of data that has been captured about events in Profiler." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A collection of events and related performance data returned by SQL Server’s database engine." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"A trace is a collection of events and data. SQL Profiler is used to collect and monitor events. Creating a trace is sometimes referred to as capturing events." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A collection of events and data returned by the Database Engine." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A record of the processing of a computer program or transaction. The information collected from a trace can be used to assess problems and performance." (IBM, "Informix Servers 12.1", 2014)

"In DB2 replication, a facility that is used to collect monitoring, auditing, and performance data for the Capture program, the Q Capture program, the Apply program, the Q Apply program, or the Replication Alert Monitor." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Data Synchronization (Definitions)

"In replication, the process that ensures the publication and destination tables contain the same schema and data. This process must occur before a subscription server can receive replicated transactions from an article or a publication." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"Refers to the process in which the article or articles subscribed to on a subscription server are initially synchronized with the original article or articles on the publication server." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

[automatic synchronization:] "Synchronization that is accomplished automatically by SQL Server when a server initially subscribes to a publication. A snapshot of the table data and schema are written to files for transfer to the Subscriber. The table schema and data are transferred by the distribution agent. No operator intervention is required." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The process of maintaining the same schema and data in a publication at a Publisher and in the replica of a publication at a Subscriber. See also initial snapshot." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The process of ensuring that the publication and destination tables contain the same schema and data. This process must occur before a new Subscriber can receive replicated transactions from a publication. It is also called initial synchronization." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"Synchronization is the process in replication of maintaining the same schema and data at a Publisher and at a Subscriber." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"Integrating, matching, or linking data from disparate sources." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)

"The continuous harmonization of data attribute values between two or more different systems, with the end result being the data attribute values are the same in all of the systems." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

[initial synchronization:] "The first synchronization for a subscription, during which system tables and other objects that are required by replication, and the schema and data for each article, are copied to the Subscriber." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The process by which a satellite downloads and runs the same DB2 database commands, operating system commands, and SQL statements from the satellite control server as the other members of its group download and then reports the results to the satellite control server." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A form of embedded middleware that allows applications to update data on two systems so that the data sets are identical. These services can run via a variety of different transports but typically require some application-specific knowledge of the context and notion of the data being synchronized." (Gartner)

"Data synchronization is the effort to ensure that, once data leaves a system or storage entity, it does not fall out of harmony with its source, thereby creating inconsistency in the data record." (Information) [source] 

 "1. In replication, the process of data and schema changes being propagated between the Publisher and Subscribers after the initial snapshot has been applied at the Subscriber. 2. In database mirroring, when a mirroring session starts or resumes, the process in which log records of the principal database that have accumulated on the principal server are sent to the mirror server, which writes these log records to disk as quickly as possible to catch up with the principal server." (Microsoft Technet)

"The process of keeping selected data in multiple data sources in agreement." (Microsoft Technet)

"The term, Synchronization, refers to the process of replicating the changes made to documents on one database to the same documents in a second instance of that database." (Couchbase)

DBMS: Distributed Database (Definitions)

"A database implemented on a network in which the component partitions are distributed over various nodes of the network. Depending on the specific update and retrieval traffic, distributing the database can enhance overall performance significantly." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database located at more than one site." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A database with pieces stored on multiple computers on a network." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A database where portions of the database are stored on computers at physically distributed locations. The entire database is the sum of all the parts." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"A logically related database that is stored over two or more physically independent sites." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A database whose tables are stored on different but interconnected computing systems." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Relational Database Management System (Definitions)

"A system that organizes data into related rows and columns. SQL Server is a relational database management system." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database, built on a model of data as existing in rows and columns, intended to embody the theoretical foundations of relational data that were originally defined by Dr. E. F. Codd at IBM. The Oracle server is one example, along with IBM's DB2, Microsoft's SQL Server, and mySQL." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"Database management system based on the relational model that supports the full range of standard SQL. Uses a series of joined tables with rows and columns to organize and store data." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit 2nd Ed ", 2002)

"A system that organizes data into related rows and columns. SQL Server is a relational database management system." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A system used to create, edit, and manage relational databases." (Johannes Link & Peter Fröhlich, "Unit Testing in Java", 2003)

"The controlling software for databases in which data is organized into related objects within a database rather than tied to a file. Each of these objects is related to another in some way." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A system that uses a database that contains tables with data. The management system part is the part allowing you access to that database, and the power to manipulate both the database and the data contained within it." (Gavin Powell, "Beginning Database Design", 2006)

"Software that organizes manipulates and retrieves data stored in a relational database." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A system that organizes data into related rows and columns. SQL Server is an RDBMS." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A database management system whose architecture is based on Dr. E. F. Codd’s relational theory. That is, it stores data in terms of simple, two dimensional tables." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"Type of DBMS that uses SQL to store data in related tables." (Martin Oberhofer et al, "The Art of Enterprise Information Architecture", 2010)

"A collection of programs that manages a relational database. The RDBMS software translates a user’s logical requests (queries) into commands that physically locate and retrieve the requested data. A good RDBMS also creates and maintains a data dictionary (system catalog) to help provide data security, data integrity, concurrent access, easy access, and system administration to the data in the database through a query language (SQL) and application programs." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A database system that organizes data into related rows and columns as specified by a relational model." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A database management system that organizes data in defined tables. " (Marcia Kaufman et al, "Big Data For Dummies", 2013)

"A collection of hardware and software that organizes and provides access to a relational database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

DBMS: Throughput (Definitions)

"The volume of work completed in a given time period. It is usually measured in transactions per second (TPS)." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"The number of operations the DBMS can do in a time unit." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"The amount of work performed by a computer system within a specified time interval; for example, the number of transactions of a certain type that can be processed per second. See also response time, workload, channel capacity." (Richard D Stutzke, "Estimating Software-Intensive Systems: Projects, Products, and Processes", 2005)

"Amount of activity a system can sustain over a period of time." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"The amount of data that is transferred from sender to receiver over time." (John Goodson & Robert A Steward, "The Data Access Handbook", 2009)

"The number of work items processed per unit of time." (Max Domeika, "Software Development for Embedded Multi-core Systems", 2011)

"Given a set of tasks to be performed, the rate at which those tasks are completed. Throughput measures the rate of computation, and it is given in units of tasks per unit time." (Michael McCool et al, "Structured Parallel Programming", 2012)

"The amount of work completed in a unit of time." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The rate at which transactions are completed in a system." (Marcia Kaufman et al, "Big Data For Dummies", 2013)

DBMS: Savepoint (Definitions)

"A marker that the user includes in a user-defined transaction. When transactions are rolled back, they can be rolled back only to the savepoint." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A marker that allows an application to roll back part of a transaction if a minor error is encountered. The application must still commit or roll back the full transaction when it is complete." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A location to which a transaction can return if part of the transaction is conditionally canceled or encounters an error, hence offering a mechanism to roll back portions of transactions." (SQL Server 2012 Glossary, "Microsoft", 2012)

"A named entity that represents the state of data and schemas at a particular point in time within a unit of work." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

[nested savepoint] "A savepoint that is included or positioned within another savepoint. Nested savepoints allow an application to have multiple levels of savepoints active at a time and allow the application to roll back to any active savepoint as required." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

 "A marker that allows an application to roll back part of a transaction if a minor error is encountered." (Microsoft Technet)

"A named SCN in a transaction to which the transaction can be rolled back." (Oracle, "Oracle Database Concepts")

"Savepoints help to implement nested transactions. They can be used to provide scope to operations on tables that are part of a larger transaction. For example, scheduling a trip in a reservation system might involve booking several different flights; if a desired flight is unavailable, you might roll back the changes involved in booking that one leg, without rolling back the earlier flights that were successfully booked." (MySQL, "MySQL 8.0 Reference Manual Glossary")

DBMS: Operational Database (Definitions)

"An OLTP database that supports the business operations - for example, logging orders and tracking customers. An operational database is usually the source of data for the data warehouse. Operational data is updated frequently to reflect the current value of all transactions." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"A database containing a company's up-to-date and modifiable information." (Glenn J Myatt, "Making Sense of Data: A Practical Guide to Exploratory Data Analysis and Data Mining", 2006)

"A database that is designed primarily to support a company’s day-to-day operations. Also known as a transactional database or production database." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed, 2011)

"A database system that runs core functions to the business in production environments. These are not test or reporting database systems, but actual systems that run the operations of the company." (Jason Williamson, Getting a Big Data Job For Dummies, 2015)

"The database of record, consisting of system-specific reference data and event data belonging to a transaction-update system. It may also contain system control data such as indicators, flags and counters. The operational database is the source of data for the data warehouse. It contains detailed data used to run the day-to-day operations of the business. The data continually changes as updates are made, and reflects the current value of the last transaction." (Information Management)

"The database that contains the live data that is viewed, retrieved, and edited in an Oracle Service Cloud application. While reports that are run on the operational database can access real-time data, the reports cannot process as much information as reports that are run on the report database." (Oracle)

"They carry out regular operations of an organisation and are generally very important to a business. They generally use online transaction processing that allows them to enter, collect and retrieve specific information about the company." (Data Floq)

DBMS: Latency (Definitions)

"The amount of time that elapses between when a change is completed on the Publisher and when it appears in the destination database on the Subscriber." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The amount of time that elapses between when a data change is completed at one server and when that change appears at another." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"The amount of time that elapses when a data change is completed at one server and when that change appears at another within a replication architecture (for example, the time between when a change is made at a publisher and when it appears at the subscriber)." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"The delay in time for a data change to be propagated between nodes in a replication topology." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

[latency of information:] "Latency is a time delay between the moment something is initiated and the moment one of its effects begins or becomes detectable. Latency of information applies this concept to changes, updates, and deletes of information." (Allen Dreibelbis et al, "Enterprise Master Data Management", 2008)

[data latency:] "Technically, the speed in which data is captured is referred to as data latency. It is a measure of data 'freshness', specifically data that are less than 24 hours old." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)

"The measure of time between two events, such as the initiation and completion of an event, or the read on one system and the write to another system." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The delay that occurs while data is processed or delivered." (Microsoft, "SQL Server 2012 Glossary", 2012)

"In replication, part or all of the approximate difference between the time that a source table is changed and the time that the change is applied to the corresponding target table." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

 "The amount of time that elapses when a data change is completed at one server and when that change appears at another server." (Microsoft Technet)

DBMS: Multidimensional Database (Definitions)

"Database in which the data is presented in data cubes, as opposed to tables in a relational database platform." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"A data warehouse design that uses fact tables and dimension tables to organize data efficiently for summarizing large groups of records." (Reed Jacobsen & Stacia Misner, "Microsoft SQL Server 2005 Analysis Services Step by Step", 2006)

"A data structure with three or more independent dimensions." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"Specialized data store that organizes facts by dimensions, such as geographical region, product line, salesperson, or time." (Linda Volonino & Efraim Turban, "Information Technology for Management" 8th Ed., 2011)

"A database optimized for data online analytical processing (OLAP) applications and for data warehousing." (Analytics Insight)

DBMS: Metadata Repository (Definitions)

 "A database or storage medium where Metadata are stored and easily accessed by people in an organization." (Margaret Y Chu, "Blissful Data ", 2004)

"A centralized database containing metadata captured from around the enterprise." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling 2nd Ed.", 2005)

"A database where metadata are stored as structured data that can be easily accessed and queried by business and technology workers." (Danette McGilvray, "Executing Data Quality Projects", 2008)

"A container of consistent definitions of business data and rules for mapping data to their actual physical locations in the system." (Judith Hurwitz et al, "Service Oriented Architecture For Dummies" 2nd Ed., 2009)

"A database constructed for the purpose of storing, managing, and making available metadata." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"A container of consistent definitions of business data and rules for mapping data to its actual physical locations in the system. |" (Marcia Kaufman et al, "Big Data For Dummies", 2013) 

"A metadata repository is a software tool or database used to store and manage metadata." (Piethein Strengholt, "Data Management at Scale", 2020)

DBMS: Repository (Definitions)

"The storage container for the metadata managed by OLAP Services. Metadata is stored in tables in a relational database and is used to define the parameters and properties of OLAP server objects." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database containing information models that, in conjunction with the executable software, manage the database." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A repository is a collection of resources that can be accessed to retrieve information." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A database for software and components, with an emphasis on revision control and configuration management. Where they keep the good stuff, in other words." (Judith Hurwitz et al, "Service Oriented Architecture For Dummies" 2nd Ed., 2009)

"A database containing information models that, in conjunction with the executable software, manage the database." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A store of information about the data assets of an organization." (Craig S Mullins, "Database Administration", 2012)

"A database for software and components, with an emphasis on revision control and configuration management (where they keep the good stuff, in other words)." (Marcia Kaufman et al, "Big Data For Dummies", 2013)

"A place where important corporate metadata is stored" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"a database for software and components, with an emphasis on revision control and configuration management (where they keep the good stuff, in other words)." (Judith S Hurwitz, "Cognitive Computing and Big Data Analytics", 2015)

"A storage location for physical data, preferably databases." (Hamid R Arabnia et al, "Application of Big Data for National Security", 2015)

"In a software context, a repository is a data store that contains the code and or data for a project." (Alex Thomas, "Natural Language Processing with Spark NLP", 2020)

"A database containing information models that, in conjunction with the executable software, manage the database." (Microsoft Technet)

DBMS: Database Design (Definitions)

"1.The process of developing a physical data model, followed by definition of all physical database objects, including tables, indexes, and sequences. 2.The physical data model and the detailed DDL for a database. The database design addresses physical constraints such as storage and performance." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The process that yields the description of the database structure. The database design process determines the database components. Database design is the second phase of the Database Life Cycle." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management 9th Ed", 2011)

DBMS: Partitioning (Definitions)

"To divide a table into logical subsets based on characteristics of the data. Partitioning is used to improve application performance or reduce the potential for conflicts in multisite update replication." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Physically separating data into areas that are more easily maintained or accessed. Data partitioning increases performance and aids in maintenance processes." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"The process of splitting a database object (usually a tablespace, table, or index) into two or more physical locations, or partitions, that is, a splitting of a logical group of pages (for example, the pages of a table) into chains or files which are physically removed from each other, perhaps on separate disks. Informix calls this fragmentation." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"The process of replacing a table with multiple smaller tables. Each smaller table has the same format as the original table, but with a subset of the data. Each partitioned table has rows allocated to it based on some characteristic of the data, such as specific key ranges. The rules that define into which table the rows go must be unambiguous. For example, a table is partitioned into two tables. All rows with primary key values lower than a specified value are allocated to one table, and all keys equal to or greater than the value are allocated to the other. Partitioning can improve application processing speeds and reduce the potential for conflicts in multisite update replication. You can improve the usability of partitioned tables by creating a view. The view, created by a union of select operations on all the partitioned tables, presents the data as if it all resided in a single table." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"Physical splitting of tables into separate sections (partitions), including parallel processing on multiple partitions and individual operations on individual partitions. One particularly efficient aspect is the capability when querying a table to read fewer than all the partitions making up a table, perhaps even a single partition. This is also known as partition pruning." (Gavin Powell, "Beginning Database Design", 2006)

[data partitioning:] "Process of moving data from a single server to one or more different data repositories. This can be vertical, in which data from a single table is split into multiple tables, or horizontal, in which the number of rows in a table are restricted and partitioned by one or more columns." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"The process of replacing a table with multiple smaller units. Tables can be partitioned horizontally or vertically." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"The method for dividing a database into manageable parts for the purpose of easier management and better performance." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"The process of splitting a table into subsets of rows or columns." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"The process of replacing a table with multiple smaller tables." (Microsoft, "SQL Server 2012 Glossary,", 2012)

"With respect to distributed databases, partitioning refers to splitting documents, tables, or graphs and distributing them to different servers." (Dan Sullivan, "NoSQL for Mere Mortals®", 2015)

[index-controlled partitioning:] "A type of partitioning in which partition boundaries for a partitioned table are controlled by values that are specified on the CREATE INDEX statement." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Partitioning is the spreading of data across multiple files across a cluster to balance large amounts of data across disks or nodes. Read-only partitions make a read-only table space that prevents updates on all tables in the table space. Other patterns can be applied on this table space to improve performance." (Piethein Strengholt, "Data Management at Scale", 2020)

[composite partitioning:] "In partitioning strategy in which a table is partitioned by one data distribution method and then each partition is further divided into subpartitions using a second data distribution method." (Oracle, "Oracle Database Concepts")

"The ability to decompose very large tables and indexes into smaller and more manageable pieces called partitions." (Oracle, "Oracle Database Concepts")

DBMS: Linked Server (Definitions)

"A definition of an OLE DB data source used by SQL Server distributed queries. The linked server definition specifies the OLE DB provider required to access the data, and includes enough addressing information for the OLE DB provider to connect to the data. Any rowsets exposed by the OLE DB data source can then be referenced as tables, called linked tables, in SQL Server distributed queries." (Microsoft Technet, "Glossary", 0)

"An abstraction of an OLE DB data source that looks like another server to the local SQL Server. A linked server has an associated OLE DB provider that manages the data source. Linked servers allow heterogeneous data access as if the data were local SQL Server data." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A database object that represents a particular data source and the attributes, including security and collation attributes, necessary to access the data source." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"An OLE DB data source used by SQL Server distributed queries." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A definition that specifies an external OLE DB database source, such as another SQL Server, or an Oracle server. Once defined, the linked server can be used for distributed queries using only the four-part name in the query." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Database objects that provide the connection information for remote data sources housed on another server. The other server could be a SQL Server, an Oracle server, a Microsoft Access database, or one of many other data sources. Linked servers are created when the remote data source will be accessed more than once or twice." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"Database objects that provide the connection information for remote data sources housed on another server. The other server could be a SQL Server, an Oracle server, a Microsoft Access database, or one of many other data sources. Linked servers are created when the remote data source will be accessed more than once or twice. See also ad hoc query." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"A definition of an OLE DB data source used by SQL Server distributed queries. The data exposed by a linked server is then referenced as tables, called linked tables." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A definition of an OLE DB data source used by SQL Server distributed queries. The linked server definition specifies the OLE DB provider required to access the data, and includes enough addressing information for the OLE DB provider to connect to the data." (Microsoft, "SQL Server 2012 Glossary", 2012)

"This is the remote servers in a distributed query." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

DBMS: Two-Phase Commit (Definitions)

"An approach for maintaining consistency over multiple systems. In the first phase, all backends are asked to confirm a requested change so that in the second phase the commitment of the updates usually succeeds." (Nicolai M Josuttis, "SOA in Practice", 2007)

"A protocol that ensures that transactions that apply to more than one server are completed on all servers or on none." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A mechanism to synchronize updates on different machines or platforms, so that they all fall or all succeed together. The decision to commit is centralized, but each participant has the right to veto. This is a key process in real-time, transaction-based environments." (Atul Apte, "Java™ Connector Architecture: Building Custom Connectors and Adapters", 2002)

"A process that ensures transactions that apply to more than one server are completed on all servers or on none." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"This is a special transaction involving two servers in which the transaction must be applied to both servers, or the entire transaction is rolled back from both servers." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A transaction processing protocol that first ensures the transaction holds locks on all records involved before committing any updates." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A protocol that ensures that transactions that apply to more than one server are completed on all servers or none at all. Two-phase commit is coordinated by the transaction manager and supported by resource managers." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A two-step process by which recoverable resources and an external subsystem are committed. During the first step, the database manager subsystems are polled to ensure that they are ready to commit. If all subsystems respond positively, the database manager instructs them to commit." (IBM, "Informix Servers 12.1", 2014)

"A mechanism that is another control used in databases to ensure the integrity of the data held within the database." (Adam Gordon, "Official (ISC)2 Guide to the CISSP CBK" 4th Ed., 2015)

"A two-step process by which recoverable resources and an external subsystem are committed. During the first step, the database manager subsystems are polled to ensure that they are ready to commit. If all subsystems respond positively, the database manager instructs them to commit. See also distributed transaction." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A feature of transaction processing systems that enables a database to be returned to the pretransaction state if an error condition occurs." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures", 2012)

"A process that ensures transactions that apply to more than one server are completed on all servers or on none." (Microsoft Technet)

"An operation that is part of a distributed transaction, under the XA specification. (Sometimes abbreviated as 2PC.) When multiple databases participate in the transaction, either all databases commit the changes, or all databases roll back the changes." (MySQL, "MySQL 8.0 Reference Manual Glossary")

"The process of committing a distributed transaction in two phases. In the first phase, the transaction processor checks that all parts of the transaction can be committed. In the second phase, all parts of the transaction are committed. If any part of the transaction indicates in the first phase that it cannot be committed, the second phase does not occur. ODBC does not support two-phase commits." (Microsoft, "ODBC Glossary")

DBMS: Extended Stored Procedure (Definitions)

"A SQL Server-provided procedure that dynamically loads and executes a function within a dynamic link library (DLL) in a manner similar to a stored procedure. Actions outside of SQL Server can be triggered and external information returned to SQL Server. Return status codes and output parameters (identical to their counterparts in regular stored procedures) are also supported." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A function in a dynamic link library (DLL) that is coded using the SQL Server 2000 Extended Stored Procedure API. The function can then be invoked from Transact-SQL using the same statements that are used to execute Transact- SQL stored procedures." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A stored procedure in SQL Server that provides an interface to external COM components (typically DLL files)." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance 70-444", 2007)

"A function in a dynamic link library (DLL) that is coded using the SQL Server Extended Stored Procedure API. The function can then be invoked from Transact-SQL using the same statements that are used to execute Transact-SQL stored procedures." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Provide a way for SQL Server to add functionality by calling stored procedures. This provides a way to affect external data and to return external data and information to SQL Server." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"Extended stored procedures, or XPs, are functions exposed through unmanaged binary DLLs that are designed to run within the SQL Server process space. XPs were used in SQL Server 2000 and prior to programmatically extend the functionality of SQL Server using languages like C and C++ that compile to native code. XPs have been deprecated and SQL CLR functions and procedures are preferred over XPs." (Michael Coles & Rodney Landrum, , "Expert SQL Server 2008 Encryption", 2008)

DBMS: Statistics (Definitions)

"Volatile data about the database, stored in the system catalog so that the optimizer has access to it." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"Information about tables and indexes stored in the data dictionary used to assist the cost-based optimizer when deciding how to run a given query." (Bob Bryla, "Oracle Database Foundations", 2004)

"SQL Server keeps statistics about the distribution of the key values in each index and uses these statistics to determine what index(es) to use in query processing." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"Information about the distribution of the key values in each index and uses these statistics to determine what index(es) to use in query processing." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"Statistics are a small sample of a whole used to represent the whole. In SQL Server, statistics are maintained on indexes and used by the query optimizer to determine which indexes to use for a given query. Instead of scanning an entire index (the entire population), statistical data (a sampling) is maintained on the index." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

[database statistics:] "In query optimization, refers to measurements about database objects, such as the number of rows in a table, number of disk blocks used, maximum and average row length, number of columns in each row, number of distinct values in each column, etc. Such statistics give a snapshot of database characteristics." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

[optimizer statistics:] "Details about the database its object used by the optimizer to select the best execution plan for each SQL statement. Categories include table statistics such as numbers of rows, index statistics such as B-tree levels, system statistics such as CPU and I/O performance, and column statistics such as number of nulls." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

[column statistics:] "Statistics about columns that the optimizer uses to determine optimal execution plans. Column statistics include the number of distinct column values, low value, high value, and number of nulls." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

[index statistics:] "Statistics about indexes that the optimizer uses to determine whether to perform a full table scan or an index scan. Index statistics include B-tree levels, leaf block counts, the index clustering factor, distinct keys, and number of rows in the index." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"Statistics about tables that the optimizer uses to determine table access cost, join cardinality, join order, and so on. Table statistics include row counts, block counts, empty blocks, average free space per block, number of chained rows, average row length, and staleness of the statistics on the table." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

DBMS: Composite Index (Definitions)

"Indexes which involve more than one column. Use composite indexes when two or more columns are best searched as a unit because of their logical relationship." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Has two or more columns as index key columns in the same table." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An index that uses more than one column in a table to index data." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[compound index:] "An index whose keys contain values derived from more than one data column." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An index that is created on two or more columns in a table." (Bob Bryla, "Oracle Database Foundations", 2004)

"Indexes that can be built on more than a single field." (Gavin Powell, "Beginning Database Design", 2006)

"An index that includes two or more fields." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"An index that is composed of more than one column. Both clustered and nonclustered indexes can be created as composite indexes." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"An index that is made of two or more columns." (Robert D. Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"An index that uses more than one column in a table to index data." (Microsoft, "SQL Server 2012 Glossary", 2012)

DBMS: Relational Database (Definitions)

"A collection of data arranged in rows and columns and manipulated using relational algebraic operations." (Joseph P Bigus, "Data Mining with Neural Networks: Solving Business Problems from Application Development to Decision Support", 1996)

"A collection of information organized in tables, each of which models a class of objects of interest to the organization [..]" (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A collection of information organized in tables. Each table models a class of objects of interest to the organization." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A collection of tables that stores data without any assumptions as to how the data is related within the tables or between the tables." (Bob Bryla, "Oracle Database Foundations", 2004)

"A method for storing data in multiple tables, where relationships exist between tables." (Margaret Y Chu, "Blissful Data ", 2004)

"A database in which data is viewed as being stored in tables consisting of columns (data items) and rows (units of information). Data from different tables can be combined to form new data relationships." (Sybase, "Glossary", 2005)

"A collection of information organized in tables. Each table models a class of objects of interest to the organization. Each column in a table models an attribute of the object. Each row in a table represents one entity in the class of objects modeled by the table. Queries can use data from one table to find related data in other tables." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"The set of requirements and fulfilling data that is developed and documented during critical parameter management. They link many-to-many relationships up and down throughout the hierarchy of the system being developed." (Clyde M Creveling, "Six Sigma for Technical Processes: An Overview for R Executives, Technical Leaders, and Engineering Managers", 2006)

"A database that organizes data in the form of tables." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A database that stores data in tables containing rows and columns, and that allows queries representing relationships among records in different tables." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A database where tables hold records containing fields. Fields holding the same values link related tables." (Rod Stephens, "Start Here!™ Fundamentals of Microsoft® .NET Programming", 2011)

"A database for storing structured data. This allows for a fixed format, usually a limited number of values in a defined order." (Kenneth A Shaw, "Integrated Management of Processes and Information", 2013)

"A database in which data is stored in multiple, interrelated tables." (Faithe Wempen, "Computing Fundamentals: Introduction to Computers", 2015)

"A database in which the information is organized into tables related to each other by specific rules." (Mike Harwood, "Internet Security: How to Defend Against Attackers on the Web" 2nd Ed., 2015)

"A database that stores related data in rows and columns in tables." (Rod Stephens, "Beginning Software Engineering", 2015)

"Essentially, a collection of tables or lists." (E C Nelson & Stephen L Nelson, "Excel Data Analysis For Dummies ", 2015)

"A database that can be perceived as a set of tables and manipulated in accordance with the relational model of data. Each database includes a set of system catalog tables that describe the logical and physical structure of the data, a configuration file containing the parameter values allocated for the database, and a recovery log with ongoing transactions and archivable transactions." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A database or database management system that stores information in tables as rows and columns of data, and conducts searches by using the data in specified columns of one table to find additional data in another table." (Microsoft Technet)

"A database in which data is viewed as being stored in tables consisting of columns (data items) and rows (units of information). Data from different tables can be combined to form new data relationships." (Sybase)

"A database that can be perceived as a set of tables and manipulated in accordance with the relational model of data." (IBM)

"A database that conforms to the relational model, storing data in a set of simple relations." (Oracle)

DBMS: Database (Definitions)

"A collection of interrelated data stored together in one or more computerized files. (IEEE," IEEE Standard Glossary of Software Engineering Terminology", 1990)

"A set of related data tables and other database objects that are organized and presented to serve a specific purpose."  (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A collection of information, data tables, and other objects that are organized and presented to serve a specific purpose, such as facilitation of searching and sorting data."  (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A preallocated portion of a device used  to store database objects and data. (Rob Scrimger et al, "MCSE TestPrep: SQL Server 6.5  Administration", 1998)

"A collection of information, tables, and other objects organized and presented to serve a specific purpose, such as searching, sorting, or recombining data."  (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A collection of tables that stores data without any assumptions as to how the data is related within the tables or between the tables." (Bob Bryla, "Oracle Database Foundations", 2004)

"A shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization." (Thomas M Connolly & Carolyn E Begg, "Database Solutions: A step-by-step guide to building databases", 2004)

"The collection of all physical files on disk that are associated with a single Oracle instance." (Bob Bryla, "Oracle Database Foundations", 2004)

"A collection of information organized in tables. Each table models a class of objects of interest to the organization. Each column in a table models an attribute of the object. Each row in a table represents one entity in the class of objects modeled by the table. Queries can use data from one table to find related data in other tables." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A collection of persistent data. In a database, data are modeled in accordance with a database model. This model defines the structure of the data, the constraints for integrity and security, and the behavior of the data." (Slawomir Zadrozny et al, "An Overview of Fuzzy Approaches to Flexible Database Querying", 2008)

"A database that stores data in tables containing rows and columns, and that allows queries representing relationships among records in different tables." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"An entity that holds data in some useful way and provides CRUD methods. Modern databases also provide sophisticated methods for joining, sorting, grouping, and otherwise manipulating the data."  (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A collection of information, tables, and other objects organized and presented to serve a specific purpose, such as searching, sorting, and recombining data. Databases are stored in files."  (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A collection of information organized in tables." (Jim Joseph et al, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A collection of records stored in a computer in a systematic way, so that a computer program can consult it to answer questions. For better retrieval and sorting, each record is usually organized as a set of data elements (facts). The items retrieved in answer to queries become information that can be used to make decisions." (Robert J Mockler & Dorothy G. Dologite, "Medical IT Systems and Their Effect on Human Resources", 2009)

"A collection of related information. The information held in the database is stored in an organised way so that specific items can be selected and retrieved quickly." (Yanqing Duan & Mark Xu, "Decision Support Systems in Small Businesses", 2009)

"A database is a tool that stores data, and lets you create, read, update, and delete the data in some manner." (Rod Stephens, "Beginning Database Design Solutions", 2009)

"An entity that holds data in some useful way and provides CRUD methods." (Rod Stephens, "Beginning Database Design Solutions", 2009)

"A collection of interrelated stored data that serves the needs of multiple users; a collection of tables in the relational model." (Toby J Teorey, ", Database Modeling and Design 4th Ed", 2010)

"An organized collection of data, usually in digital form."  (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed, 2012)

"A computer system intended to store large amounts of information reliably and in an organized fashion. Most databases provide users with convenient access to the data, along with helpful search capabilities." (Marcia Kaufman et al, "Big Data For Dummies", 2013)

"A structured collection of units of data organized around some topic or theme" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"Systematically organized or structured repository of indexed information that allows easy retrieval, updating, analysis, and output of data." (Siddhartha Duggirala, "Big Data Architecture: Storage and Computation", 2014)

"A collection of interrelated persistent information stored and organized as a unit in order to serve a specific purpose and satisfy the demands of a set of users. A database can be considered to be an electronic filling system stored on mass-storage systems such as magnetic tape or disk. A database is one component of a database management system." (Ioannis Kouris et al, "Indexing and Compressing Text", 2015)

"a computer system intended to store large amounts of information reliably and in an organized fashion. Most databases provide users convenient access to the data, along with helpful search capabilities." (Judith S Hurwitz, "Cognitive Computing and Big Data Analytics", 2015)

"A structured set of data held in a computer, especially one that is accessible in various ways." (Ronald R Yager & Rachel L Yager, "Fuzzy Social Network Modeling for Influencing Consumer Behavior", 2015)

"Collection of information or data organized together, with individual element having the same set of fields. It is a component of the database management system." (Hamid R Arabnia et al, "Application of Big Data for National Security", 2015)

"Essentially, a collection of tables or lists." (E C Nelson & Stephen L Nelson, "Excel Data Analysis For Dummies ", 2015)

"A set of data contained in a location on a network, computer, or server. Typically, different data sets are stored in different databases. Examples of these databases include inventory, selling price point, and sales, divided into total dollar sales and unit sales."  (Brittany Bullard, "Style and Statistics", 2016)

"A physical set of data records." (Andrew Pham et al, "From Business Strategy to Information Technology Roadmap", 2016)

"A collection of information that is organized so that it can be easily accessed, managed, and updated." (Jonathan Ferrar et al, "The Power of People: Learn How Successful Organizations Use Workforce Analytics To Improve Business Performance", 2017)

"A database is a collection of information (data) that is organized so that it can easily be accessed, managed, and updated. It is the collection of schemes, tables, queries, reports, views and other objects. The data is typically organized to model aspects of reality in a way that supports processes requiring information. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images." (Alessandra Meschini et al, "Expanded Cultural Heritage Representation: Digital Applications for Mixed-Reality Experiences", 2017)

"A collection of data related to a common subject organized in a known structure (the currently used database is a relational database)." (Dan Ophir, "Visualization and Storage of Big Data for Linguistic Applications", 2018)

"A collection of interrelated or independent data items that are stored together to serve one or more applications." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A set of related data tables and other database objects that are organized to serve a specific purpose." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A database is a piece of software used to organize data, generally stored and accessed electronically from a computer system."  (Piethein Strengholt, "Data Management at Scale", 2020)

"A complex combination of structured data in tables that relate to one another, allowing the interactive management of information with automatic implementations, quick updates and specific interrogations." (Cristina Boido et al, "Digital Tools Aimed to Represent Urban Survey", 2021)

"A structured set of data held in a computer, especially one that is accessible in various ways." (Ingrid N Pinto-López, "Fuzzy Reliability Theory: A Bibliometric-Based Review", 2021)

"A digital collection of data stored via a certain technique." (Analytics Insight)