🛢DBMS: Hash Joins (Definitions)

"A sophisticated join algorithm that builds an interim structure to derive result sets." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A method for producing a joined table. Given two input tables Table1 and Table2, processing is as follows: (a) For each row in Table1, produce a hash. Assign the hash to a hash bucket. (b) For each row in Table2, produce a hash. Check if the hash is already in the hash bucket. If it is: there's a join. If it is not: there's no join." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"An efficient method of searching two tables to be joined when they have very low selectivity (i.e., very few matching values). Common values are matched in fast memory, then the rest of the data record is obtained using hashing mechanisms to access the disk only once for each record." (Sam Lightstone et al, "Physical Database Design: The Database Professional’s Guide to Exploiting Indexes, Views, Storage, and More", 2007)

"A method for joining large data sets. The database uses the smaller of two data sets to build a hash table on the join key in memory. It then scans the larger data set, probing the hash table to find the joined rows." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The hash join is based on a hash function that provides access to items in the joining data structure in constant time. A hash function maps arbitrary inputs to fixed length keys, even though the inputs might have variable lengths. The joining data structure for the hash join is a so-called hash map, which implements an associative array that maps keys to values." (Hasso Plattner, "A Course in In-Memory Data Management: The Inner Mechanics of In-Memory Databases" 2nd Ed., 2014)

 "A join in which the database uses the smaller of two tables or data sources to build a hash table in memory. The database scans the larger table, probing the hash table for the addresses of the matching rows in the smaller table." (Oracle, "Oracle Database Concepts")

🛢DBMS: Performance Baseline (Definitions)

 "A set of metrics gathered during a performance analysis process that forms the basis of a performance tuning methodology." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A baseline is a known starting point for something. In the context of the MCITP Database Developer certification, it's a known starting point for a server. For example, when creating a performance baseline, we would measure the four core resources of a system: CPU, memory, disk, and network. A performance baseline would take a snapshot of the resources (perhaps every 30 minutes) over a period of about a week. Six months later, another counter log could be created, and by comparing it to the baseline, an administrator can identify what has changed." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A baseline measurement is taken to serve as a point of comparison for subsequent measurement." (Laura Sebastian-Coleman, "Measuring Data Quality for Ongoing Improvement", 2012)

"In the context of AWR, the interval between two AWR snapshots that represent the database operating at an optimal level." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The beginning point, based on an evaluation of output over a period of time, used to determine the process parameters prior to any improvement effort; the basis against which change is measured." (ASQ)

"Benchmark used as a reference point" (ITIL)

🛢DBMS: Semantic Data Model (Definitions)

"Semantic data model provides a vocabulary for expressing the meaning as well as the structure of database data." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A design tool for databases that uses concept-level language elements. The main role of semantic models is that they can provide an abstract approach; they are easy to understand and they provide database independence." (László Kovács et al, "Ontology-Based Semantic Models for Databases", 2009) 

"A high level data model. It is usually based on concepts and it uses a graphical formalism. It contains only the key, the semantic properties of the data structure. It does not cover the details of the implementation." (László Kovács & Tanja Sieber, "Multi-Layered Semantic Data Models",  Encyclopedia of Artificial Intelligence, 2009)

"A conceptual data model that provides structure and defines meaning for non-tabular data, making that meaning explicit enough that a human or software agent can reason about it." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A semantic data model is a conceptual data model with semantic information included." (Michael M David & Lee Fesperman, "Advanced SQL Dynamic Data Modeling and Hierarchical Processing", 2013)

"The first of a series of data models that more closely represented the real world, modeling both data and their relationships in a single structure known as an object. The SDM, published in 1981, was developed by M. Hammer and D. McLeod." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" 11th  Ed., 2014)

"The development of descriptions and representations of data in such a way that the latter’s meaning is explicit, accurate, and commonly understood by both humans and computer systems." (Panos Alexopoulos, "Semantic Modeling for Data", 2020)

"The semantic data model is a method of structuring data in order to represent it in a specific logical way. It is a conceptual data model that includes semantic information that adds a basic meaning to the data and the relationships that lie between them. This approach to data modeling and data organization allows for the easy development of application programs and also for the easy maintenance of data consistency when data is updated." (Techopedia) [source]

🛢DBMS: Physical Data Model (Definitions)

"The Physical data model supports the needs of the database administrator and application developers, who focus on the physical implementation of the model in a database." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"In the ANSI four-schema architecture, this is the organization of data used to place it in specific storage media. This is in terms of 'Tablespaces', 'Cylinders', and so on." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"A model in which the physical characteristics (location, path, and format) are described for the data. Both hardware- and software-dependent. See also physical design." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"The logical data model transformed into a physical implementation using a specific DBMS product (e.g., DB2, Oracle, SQL Server, etc.)." (Craig S Mullins, "Database Administration", 2012)

"A model in which the physical characteristics (location, path, and format) are described for the data. Both hardware- and software-dependent." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management  Ed. 11", 2014)

"The physical definition of the shape and structure of data (as defined to the DBMS)" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"Model of a database expressed at platform dependent level in the way accepted by a specific database management system. Beside the data it can also contain implementation of business logic in the form of stored procedures or transaction definitions." (Iwona Dubielewicz et al, "Quality-Driven Database System Development within MDA Approach", 2015)

"In DB2 data warehousing, a metadata model that represents the tables and other objects in a database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"A data model that represents the implementation of the data contained in a data structure." (IEEE 610.5-1990)

🛢DBMS: Relational Model (Definitions)

"A method of organizing data into two-dimensional tables made up of rows and columns. The model is based on the mathematical theory of relations, a part of set theory." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A model that provides a two-dimensional structure to data. The relational database model more or less throws out the window the concept and restriction of a hierarchical structure, but does not completely abandon data hierarchies. Any table can be accessed directly with having to access all parent objects. Precise data values (such as primary keys) are required to facilitate skirting the hierarchy (to find individual records) in specific tables." (Gavin Powell, "Beginning Database Design", 2006)

"A paradigm for describing the structure of a database in which entities are represented as tables, and relationships between the entities are represented by matching data." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The relational model, based on mathematical set theory, represents data as independent relations. Each relation (table) is conceptually represented as a matrix of intersecting rows and columns. The relations are related to each other through the sharing of common entity characteristics (values in columns)." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A database model based on first-order predicate logic [...]" (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures", 2012)

"A form of data where data is normalized" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"A type of model that aims to identify relationships of interest and quantify the strength of relationship between individuals or entities. Common examples include market basket analysis and social network analysis." (Evan Stubbs, "Big Data, Big Innovation", 2014)

"Data represented as a set of related tables or relations." (Jeffrey A Hoffer et al, "Modern Systems Analysis and Design" 7th Ed., 2014)

"A database model in which data and the relationships among them are organized into tables" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"Relational modeling is a popular data modeling technique to reduce the duplication of data and ensure the referential integrity of the data." (Piethein Strengholt, "Data Management at Scale", 2020)

"(1) A data model whose pattern or organization is based on a set of relations, each of which consists of an unordered set of tuples. (2) A data model that provides for the expression of relationships among data elements as formal mathematical relations." (IEEE 610.5-1990)

🛢DBMS: Table Scan (Definitions)

"A method of accessing a table by reading every row in the table. Table scans are used when there are no conditions (where clauses) on a query, when no index exists on the clauses named in the query, or when the SQL Server optimizer determines that an index should not be used because it is more expensive than a table scan." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"The means by which SQL Server searches a table sequentially without using an index. SQL Server starts at the beginning of the table and reads every row in the table to find the rows that meet the search criteria of the query." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The means by which SQL Server performs a search on a table. SQL Server starts at the beginning of the table and reads every row in the table to find the rows that meet the search criteria of the query." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"A search of an entire table, row by row." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A data retrieval operation where the database engine must read all the pages in a table to find the rows that qualify for a query." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"This is the process of scanning each extent of a table for a needed record." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"The process of examining all rows of data in a table sequentially." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

🛢DBMS: Data Type (Definitions)

"An attribute that specifies what type of information can be stored in a column or variable. System-supplied data types are provided by SQL Server; user-defined data types can also be created. See also base data type." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An attribute that specifies the type of information that can be stored in a column, parameter, or variable." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"The type of data that a column can hold. Types include numbers, fixed-length strings, variable-length strings, and so forth." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"An attribute that specifies what type of information can be stored in a column, parameter, or variable. There are two different data types: system supplied and user defined." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"Alternate form: datatype 1.A category of physical data structures with common physical properties and uses, such as numeric, alphanumeric, packed decimal, floating point, datetime, etc. 2.A set of distinct values characterized by properties of those values and by operations on those values. [ISO/IEC 11404:1996, 4.11]" (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A classification identifying one of various types of data. Each column in a physical database design must have a data type assigned. Examples include integer, character, etc." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures 2nd Ed", 2012)

"A set of possible values, together with all the operations that know how to deal with those values. For example, a numeric data type has a certain set of numbers that you can work with, as well as various mathematical operations that you can do on the numbers, but would make little sense on, say, a string such as "Kilroy". Strings have their own operations, such as concatenation. Compound types made of a number of smaller pieces generally have operations to compose and decompose them, and perhaps to rearrange them. Objects that model things in the real world often have operations that correspond to real activities. For instance, if you model an elevator, your elevator object might have an opendoor method." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

"Classifications that identify a type or types of data (such as integer), which determines the possible values for that type." (Matt Telles, "Beginning Programming", 2014)

"A description of the set of values and the basic set of operations that can be applied to values of the type" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"In SQL, a descriptor of a set of values and a set of permitted operations. A data type determines the kind of value that a column, literal, parameter, special register, or variable can have or that can be the result of an expression, a function, or a method." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Object (Definitions)

"Conceptually a container that holds data in the database. Objects have various properties including an access control list." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"One of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure. Also called a database object. In COM programming, an object has properties and methods and exposes interfaces; for example, the SQL-DMO is a hierarchy of COM objects." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An active data value that has characteristics and properties." (Greg Perry, "Sams Teach Yourself Beginning Programming in 24 Hours 2nd Ed.", 2001)

"In databases, one of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"An instance of an item of interest to the data model." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"In databases, one of the components of a database: a table, index, trigger, view, key, constraint, default, rule, user-defined data type, or stored procedure. In object-oriented programming, an instance of a class." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A set of instructions, generated at application compilation time, that is created and managed by a DBMS. The access plan predetermines the way an application’s query will access the database at run time." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" Ed. 11, 2014)

"A database component in a database. Can also refer to the database itself." (Technet)

"A database object in a relational database is a data structure used to either store or reference data." (Techopedia) [source]

"An object in the database that can be manipulated with SQL. Schema objects such as tables and indexes reside in schemas. Nonschema objects such as directories and roles do not reside in schemas." (Oracle)

"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." (IBM)

🛢DBMS: Recursion (Definitions)

 "Occurs when one process calls itself to run again. With triggers, it's the process of a trigger firing itself. Indirect recursion is where an update to Table1 fires a trigger that affects Table2 that fires a trigger that updates Table1 again. Direct recursion is where an update to Table1 fires a trigger that affects Table1 again that fires the trigger again." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Recursion is a method of defining functions, CTEs, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"When a function calls itself as part of its computation. A termination condition is required to prevent an infinite recursion. See also tail-call recursion." (Dean Wampler & Alex Payne, "Programming Scala", 2009)

"The process of a method calling itself." (Rod Stephens, "Stephens' Visual Basic® Programming 24-Hour Trainer", 2011)

"When a function calls itself as part of its computation. A termination condition is required to prevent an infinite recursion. You can also have cycles of recursion between two or more functions. See also tail-call recursion." (Dean Wampler, "Functional Programming for Java Developers", 2011)

"Recursion is a method of defining functions, CTEs, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide 3rd Ed", 2012)

"The act of a function being re-entered while an instance of the function is still active in the same thread of execution. In the simplest and most common case, a function directly calls itself, although recursion can also occur between multiple functions. Recursion is supported by storing the state for the continuations of partially completed functions in dynamically allocated memory, such as on a stack, although if higher-order functions are supported a more complex memory allocation scheme may be required. Bounding the depth of recursion can be important to prevent excessive use of memory." (Michael McCool et al, "Structured Parallel Programming", 2012)

"The art of defining something (at least partly) in terms of itself, which is a naughty no-no in dictionaries but often works out okay in computer programs if you’re careful not to recurse forever (which is like an infinite loop with more spectacular failure modes)." (Jon Orwant et al, "Programming Perl, 4th Ed.", 2012)

"When a function or method calls itself. In mathematical terms, this is when a function is defined in terms of itself." (Mark C Lewis, "Introduction to the Art of Programming Using Scala", 2012)

"the act of defining a function in terms of itself." ( Manish Agrawal, "Information Security and IT Risk Management", 2014)

"The type of relationship where part of the definition makes a reference to the item being defined" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"A method of defining functions, common table expressions, procedures, or triggers in such a way that they call themselves or cause themselves to be called multiple times." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

"The ability of an algorithm to call itself" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"A process in which a problem is broken down into one or more self-similar subproblems, which are then also similarly broken down, until one reaches a base case where the solution is well-defined, often by definition." (O Sami Saydjari, "Engineering Trustworthy Systems: Get Cybersecurity Design Right the First Time", 2018)

🛢DBMS: Trigger (Definitions)

"A special form of stored procedure that goes into effect when a user gives a change command such as insert, delete, or update to a specified table or column. Triggers are often used to enforce referential integrity." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A special form of stored procedure that goes into effect when data within a table is modified. Triggers are often created to enforce integrity or consistency among logically related data in different tables." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A special type of stored procedure that is set off by actions taken on a table. Triggers allow for complex relationships between tables and complex business rules to be checked automatically." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A stored procedure that executes automatically when data in a specified table is modified. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"Code stored in the database that executes automatically when certain events occur. Traditionally associated only with table write events such as INSERT, UPDATE, or DELETE, newer versions of Oracle provide the ability to define triggers on views and on other system events such as logon, logoff, and system error." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A stored procedure that executes when data in a specified table is modified. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A trigger is a stored procedure that is fired when data is modified from a table using any of the three modification statements: DELETE, INSERT, or UPDATE. FOR and AFTER are synonymous, and are usually implied when referring to triggers, rather than INSTEAD OF triggers. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A chunk of code that executes when a specified event occurs, usually before or after an INSERT, UPDATE, or DELETE command." (Gavin Powell, "Beginning Database Design", 2006)

"A database method that is automatically invoked as the result of Data Manipulation Language (DML) activity within a persistence mechanism." (Pramod J Sadalage & Scott W Ambler, "Refactoring Databases: Evolutionary Database Design", 2006)

"A stored procedure that is fired when data is modified from a table using any of the three modification statements DELETE, INSERT, or UPDATE. FOR and AFTER are synonymous and are usually implied when referring to triggers rather than INSTEAD OF triggers. Triggers are often created to enforce referential integrity or consistency among logically related data in different tables." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"A stored procedure that executes when certain conditions occurs such as when a record is created, modified, or deleted. Triggers can perform special actions such as creating other records or validating changes." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A type of stored procedure that fires in response to action on a table. DML triggers are associated with INSERT, UPDATE, and DELETE statements. DDL triggers are associated with CREATE, ALTER, and DROP statements." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Stored in, and managed by, your database server, this software is executed when a certain event occurs. These events can range from information creation or modification to structural changes to your database. When the event occurs, the trigger is executed, causing a pre-determined set of actions to take place. These actions can encompass data validation, alerts, warnings, and other administrative operations. Triggers can invoke other triggers and stored procedures." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"A stored procedure that executes in response to a Data Manipulation Language (DML) or Data Definition Language (DDL) event." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"A SQL program module that is executed when a specific data modification activity occurs. Triggers are stored in the database they manipulate." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A stored procedure that can be triggered and executed automatically when a database operation such as insert, update, or delete takes place." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"A procedural SQL code that is automatically invoked by the relational database management system upon the occurrence of a data manipulation event." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A software routine guaranteed to execute when an event occurs. Often a trigger will monitor changes to data values. A trigger includes a monitoring procedure, a set or range of values to check data integrity, and one or more procedures invoked in response, which may update other data or fulfill a data subscription." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"An event that causes a handler to be run." (Jon Orwant et al, "Programming Perl, 4th Ed.", 2012)

"An event-driven specialized procedure that is attached to database tables; typically implemented to support data integrity requirements." (Craig S Mullins, "Database Administration", 2012)

"A database object that is associated with a single base table or view and that defines a rule. The rule consists of a set of SQL statements that runs when an insert, update, or delete database operation occurs on the associated base table or view." (IBM, "Informix Servers 12.1", 2014)

"A database object that is associated with a single base table or view and that defines a rule. The rule consists of a set of SQL statements that runs when an insert, update, or delete database operation occurs on the associated base table or view." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

 "A PL/SQL or Java procedure that fires when a table or view is modified or when specific user or database actions occur. Procedures are explicitly run, whereas triggers are implicitly run." (Oracle, "Oracle Database Concepts")

"A stored procedure that executes in response to a data manipulation language (DML) or data definition language (DDL) event." (Microsoft Technet,)

🛢DBMS: Attribute (Definitions)

"A qualifier of an entity or a relation describing its character quantity, quality, degree, or extent. In database design, tables represent entities and columns represent attributes of those entities. For example, the title column represents an attribute of the entity titles." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A column (field) in a dimension table." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit" 2nd Ed., 2002)

"An attribute is the lowest level of information relating to any entity. It models a specific piece of information or a property of a specific entity. Dimensional modeling has a more restrictive definition; it refers to information that describes the characteristics of a dimension." (Claudia Imhoff et al, "Mastering Data Warehouse Design", 2003)

"A data item that has been 'attached' to an entity. By doing this, a distinction can be made between the generic characteristics of the data item itself (for instance, data type and default documentation) and the entity-specific characteristics (for example, identifying and entity-specific documentation). It’s a distinct characteristic of an entity for which data is maintained. An attribute is a value that describes or identifies an entity, and an entity contains one or more attributes that characterize the entity as a whole. An entity example is Employee, and an attribute example is Employee Last Name." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"A property that can assume values for entities or relationships. Entities can be assigned several attributes (for example, a tuple in a relationship consists of values). Some systems also allow relationships to have attributes as well." (William H Inmon, "Building the Data Warehouse", 2005)

"Information about a specific dimension member." (Reed Jacobsen & Stacia Misner, "Microsoft SQL Server 2005 Analysis Services Step by Step", 2006)

"The equivalent of a relational database field, used more often to describe a similar low-level structure in object structures." (Gavin Powell, "Beginning Database Design", 2006)

"The differing data items within a relation. An attribute is a named column of a relation." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"The formal database term for column." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"Individual data element that is represented and stored in a dimension. Each attribute contains data relating to that dimension." (Laura Reeves, "A Manager's Guide to Data Warehousing", 2009)

"A primitive data element that provides descriptive detail about an entity; a data field or data item in a record. For example, lastname would be an attribute for the entity customer. Attributes may also be used as descriptive elements for certain relationships among entities." (Toby J Teorey, "Database Modeling and Design 4th Ed", 2010)

"A characteristic of an entity or object. An attribute has a name and a data type." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"Characteristic describing an entity. Also known as a field." (Linda Volonino & Efraim Turban, "Information Technology for Management 8th Ed", 2011)

"A single characteristic or additional piece of information (financial or non-financial) that exists in a database." (Microsoft, "SQL Server 2012 Glossary", 2012)

"An inherent fact, property, or characteristic describing an entity. Every attribute does one of three things: describes, identifies, or relates." (Craig S Mullins, "Database Administration", 2012)

"In modeling, an attribute represents a characteristic of an entity. Because of this use, attribute is sometimes understood as a data element (which is a component piece of a data used to represent an entity), or a field (which is part of a system used to display or intake data), or a column (which is a place in a table to store a defined characteristic of a represented entity, that is, to store values associated with data elements)." (Laura Sebastian-Coleman, "Measuring Data Quality for Ongoing Improvement ", 2012)

"A data element that describes an entity or a relationship. Each attribute applies to every occurrence of its entity or relationship." (James Robertson et al, "Complete Systems Analysis: The Workbook, the Textbook, the Answers", 2013)

"In the context of information, a descriptor that is not usually associated with a numerical value. Some examples are bad, excellent, red, green, tall, small, wide, far, heavy, fast, portrait, and scenic." (Kenneth A Shaw, "Integrated Management of Processes and Information", 2013)

"A value of data that is distinguishable from other values" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

"The property or characteristic of an object that can be distinguished quantitatively or qualitatively by human or automated means." (David Sutton, "Information Risk Management: A practitioner’s guide", 2014)

"Characteristics of an object we capture in a catalog or model for data management purposes. Example: last name is an attribute of a person." (Gregory Lampshire, "The Data and Analytics Playbook", 2016)

🛢DBMS: Data Replication (Definitions)

 "Duplication of table schema and data or stored procedure definitions and calls from a source database to a destination database, usually on separate servers." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A process that copies and distributes data and database objects from one database to another and then synchronizes information between databases for consistency." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"The duplication of I/O from one set of disks to another similar set, on a file level." (Tom Petrocelli, "Data Protection and Information Lifecycle Management", 2005)

"A set of technologies for copying and distributing data and database objects from one database to another and then synchronizing between databases to maintain consistency." (Thomas Moore, "MCTS 70-431: Implementing and Maintaining Microsoft SQL Server 2005", 2006)

"This is a process that copies data from one database to another." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Process of copying data and database objects from one data source to another across a network. This is done to synchronize two databases or to maintain a remote copy of a database." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"A process whereby information is published from a database server and sent to one or more subscribers. Data may be transferred proactively by the publisher or requested by the subscribers. See also publishand- subscribe." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"A group of technologies within SQL Server 2005 that are used to copy and distribute data and database objects from one database to another. Data is then regularly synchronized to maintain consistency. Replication uses a publishing metaphor with Publishers (data source), Distributors (process responsible for replicating the data and/or objects), and Subscribers (data target)." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A feature allowing multiple database servers to share the same data, thereby ensuring redundancy and facilitating load balancing." (MongoDb, "Glossary", 2008)

"A process whereby information is published from a database server and sent to one or more subscribers. Data may be transferred proactively by the publisher or requested by the subscribers." (Robert D. Schneider and Darril Gibson, "Microsoft SQL Server 2008 All-In-One Desk Reference For Dummies", 2008)

"A set of techniques and technologies to make and then maintain a copy of data from a source database. Different approaches support different synchronization and performance requirements." (Allen Dreibelbis et al, "Enterprise Master Data Management", 2008)

"The process of storing data in multiple databases while ensuring that it remains consistent. For example, one database might contain a master copy of the data and other satellite databases might hold read-only copies to let clerks view data quickly without impacting the main database." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"Carrying out an identical transaction on two copies of the data in sequence." (David G Hill, "Data Protection: Governance, Risk Management, and Compliance", 2009)

"A method for creating copies of the database, either in real time or in a deferred mode." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"The storage of duplicated database fragments at multiple sites on a DDBMS. Duplication of the fragments is transparent to the end user. Used to provide fault tolerance and performance enhancements." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"The copying of data from a data source to one or more target environments based on rules." (Craig S Mullins, "Database Administration", 2012)

"The process of copying content and/or configuration settings from one location, generally a server node, to another. Replication is done to ensure synchronization or fault tolerance." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The process of maintaining a defined set of data in more than one location. Replication involves copying designated changes for one location (a source) to another (a target) and synchronizing the data in both locations." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢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)