30 March 2009

DBMS: Flat File (Definitions)

"A simple data structure, often implemented on a mainframe, that relies on nonrelational files, such as IBM VSAM files." (Ralph Kimball & Margy Ross, "The Data Warehouse Toolkit 2nd Ed ", 2002)

"A collection of records containing no data aggregates, nested repeated data items, or groups of data items." (William H Inmon, "Building the Data Warehouse", 2005)

"A collection of records that are related to one another that haven’t been organized to meet relational normal forms. Originally a file was stored only outside a database. Now you can refer to a table structured this way as a flat file." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"A data structure that contains records with no inherent relationships." (Evan Levy & Jill Dyché, "Customer Data Integration", 2006)

"A term generally applying to an unstructured file, such as a text file." (Gavin Powell, "Beginning Database Design", 2006)

"A file in which the fields of records are simple atomic values." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A plain old text file used to store data. A flat file isn't very fancy and provides few tools for querying, sorting, grouping, and performing other database operations but flat files are very easy to use." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"A file in which all the attribute fields are atomic, that is, single valued." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A file consisting of records of a single record type in which there is no embedded structure information that governs relationships between records." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Plain text file wherein each line of the file holds one record, typically with fields separated by delimiters, such as commas or tabs." (Craig S Mullins, "Database Administration", 2012)

"A collection of records where the structure of each record is identical" (Daniel Linstedt & W H Inmon, "Data Architecture: A Primer for the Data Scientist", 2014)

29 March 2009

DBMS: Data 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 representation, usually graphical, of objects and their relationships, generally undertaken as part of designing an Oracle database application." (Bill Pribyl & Steven Feuerstein, "Learning Oracle PL/SQL", 2001)

"A formal way of describing the relationship between entities in a database to a database management system." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

"A data model is an abstraction or representation of the data in a given environment. It is a collection and subsequent verification and communication method for fully documenting the data requirements used in the creation of accurate, effective, and efficient physical databases. The data model consists of entities, attributes, and relationships." (Claudia Imhoff et al, "Mastering Data Warehouse Design", 2003)

"A data model is a schematic showing the data in the warehouse, how the data relate to other data, and how the data should be structured. It is used to ensure that the data warehouse can substantiate all business requirements." (Margaret Y Chu, "Blissful Data", 2004)

"An integrated collection of concepts for describing data, relationships between data, and constraints on the data used by an organization." (Thomas M Connolly & Carolyn E Begg, "Database Solutions: A step-by-step guide to building databases", 2004)

"The specification of data structures and business rules needed to support a defined set of functions (sometimes called an Information Model); usually depicted in a diagram consisting of entities and relationships." (Margaret Y Chu, "Blissful Data ", 2004)

"(1) A data model is an abstract, self-contained, logical definition of the data structures, data operators, and so forth, that together make up the abstract machine with which users interact. (2) A data model is a model of the persistent data of some particular enterprise." (Christopher J Date, "Database in Depth", 2005)

"A data model is the specification of data structures and business rules to represent business requirements. This is an abstraction that describes one or more aspects of a problem or a potential solution addressing a problem." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

"A model that provides a two-dimensional structure to data." (Gavin Powell, "Beginning Database Design", 2006)

[object database model:] "A model that provides a three-dimensional structure to data where any item in a database can be retrieved from any point very rapidly." (Gavin Powell, "Beginning Database Design", 2006)

"(1) The logical data structures, including operations and constraints provided by a DBMS for effective database processing; (2) the system used for the representation of data (for example, the ERD or relational model). " (William H Inmon & Anthony Nesavich, "Tapping into Unstructured Data", 2007)

"A formal description of data managed by a business process. In most cases, these data are stored via a Database Management System (DBMS), and are also referenced by an Information System (IS) and, possibly, by a Decision Support Systems (DSS)" (C Combi & G Pozzi, "Workflow Management Systems for Healthcare Processes", 2008)

[Entity Data Model] "An EDM is an abstract logical representation of a physical database, used to implement database connectivity in the middle or client tiers." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

[navigational data model:] "A data model where relationships between entities are represented by physical data structures (for example, pointers or indexes) that provide the only paths for data access." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"A formal description language to describe and to manipulate the investigated data instances. It contains three components: a static structural part, an integrity part and a manipulation part." (László Kovács & Tanja Sieber, "Multi-Layered Semantic Data Models" [in "Encyclopedia of Artificial Intelligence"], 2009)

"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)

"An abstraction of how individual data elements relate to each other. It visually depicts how the data is to be organized and stored in a database. A data model provides the mechanism to document and understand how data is organized. (Laura Reeves, "A Manager's Guide to Data Warehousing", 2009)

"The formal way of expressing relationships in a database." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"A representation of the structure of data. As used in this book, the term refers to a conceptual data model, which describes data in terms of their inherent semantics, without regard to how they might be organized in a physical database. Some use the term to describe a logical data model that organizes data in terms of a specific data management technology, such as relational tables and columns, object-oriented classes, or ISAM hierarchies." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"A model that includes formal data names, comprehensive data definitions, proper data structures, and precise data integrity rules. A complete data model must include all four of these components." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"A representation, usually graphic, of a complex 'real-world' data structure. Data models are used in the database design phase of the database life cycle." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management 9th Ed", 2011)

"A data model is a visual representation of data content and the relationships, created for purposes of understanding how data is or might be organized, and for ensuring the comprehensibility and usability of that way of organizing data." (Laura Sebastian-Coleman, "Measuring Data Quality for Ongoing Improvement ", 2012)

"A representation, usually graphic, of a complex 'real-world' data structure. Data models are used in the database design phase of the database life cycle." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" 11th Ed., 2014)

[Entity Data Model (EDM):] "An abstract logical representation of a physical database, used to implement database connectivity in the middle or client tiers." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

"Represents data objects and their relationships with each other. Data models form the basis for data integration at the conceptual level as well as the improvement of data quality, such as with regard to the reduction of data redundancy.  Data models are one component of the data architecture." (Boris Otto & Hubert Österle, "Corporate Data Quality", 2015)

"A visual means of depicting data and its relationship to other data." (Gregory Lampshire, "The Data and Analytics Playbook", 2016)

"A description of the objects represented by a computer system together with their properties and relationships." (Besma Khalfi et al, "Enhanced F-Perceptory Approach for Dealing with Geographic Data Imprecision from the Conceptual Modeling to the Fuzzy Geographical Database Building", 2017)

"1. A representation, using text and/or graphics, of the definition, characterization, and relationships of data in a given environment. 2. No longer used, the DBMS architecture (hierarchical, network, relational, etc.)." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"In a data-centric benchmark, a database schema and a protocol for instantiating this schema, i.e. , generating synthetic data or reusing real-life data." (Jérôme Darmont, "Data-Centric Benchmarking", Encyclopedia of Information Science and Technology, Fourth Edition, 2018)

"An abstract model that describes how data is presented and used." (Piethein Strengholt, "Data Management at Scale", 2020)

"A description of data that consists of all entities represented in a data structure or database and the relationships that exist among them." (IEEE 610.5-1990)

21 March 2009

DBMS: Constraints (Definitions)

"A restriction placed upon the value that can be entered into a column or a row. Values can be equal to, greater than, or less than. A constraint limits the input." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A property assigned to a table column that prevents certain types of non-valid data values from being placed in the column." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A condition defined against a column or columns on a table in the database to enforce business rules or relationships between tables in the database." (Bob Bryla, "Oracle Database Foundations", 2004)

"A database object that can be applied to tables to enforce different types of data integrity." (Sara Morganand & Tobias Thernstrom , "MCITP Self-Paced Training Kit : Designing and Optimizing Data Access by Using Microsoft SQL Server 2005 - Exam 70-442", 2007)

"(1) A restriction on a business action and the resulting data. (2) The database mechanism for enforcing such." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures 2nd Ed", 2012)

"A rule that limits the values that can be inserted, deleted, or updated in a table." (Sybase)

20 March 2009

DBMS: Data Source (Definitions)

"The source of data for an object such as a cube or a dimension. Also, the specification of the information necessary to access source data. Sometimes refers to a DataSource object." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A repository for storing data. An ODBC/JDBC term." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A file that contains the connection string that Analysis Services uses to connect to the database that hosts the data as well as any necessary authentication credentials." (Reed Jacobsen & Stacia Misner, "Microsoft SQL Server 2005 Analysis Services Step by Step", 2006)

"A system or application that generates data for use by another system or by an end user. The data source may also be the system of origin for the data." (Evan Levy & Jill Dyché, "Customer Data Integration", 2006)

"An information store that can be connected to by various SQL Server technologies such as SQL Server Reporting Services for data retrieval." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"An entity or group of entities from which data can be collected. The entities may be people, objects, or processes." (Jens Mende, "Data Flow Diagram Use to Plan Empirical Research Projects", 2009)

"An object containing information about the location of data. The data source leverages a connection string." (Jim Joseph et al, "Microsoft® SQL Server™ 2008 Reporting Services Unleashed", 2009)

"A repository of data to which a federated server can connect and then retrieve data by using wrappers. A data source can contain relational databases, XML files, Excel spreadsheets, table-structured files, or other objects. In a federated system, data sources seem to be a single collective database." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

19 March 2009

DBMS: Scalar Aggregate (Definitions)

"An aggregate function that produces a single value from a select statement that does not include a group by clause. This is true whether the aggregate function is operating on all the rows in a table or on a subset of rows defined by a where clause." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

[vector aggregate:] "A value that results from using an aggregate function with a group by clause." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"When aggregate functions are applied to the whole or partial table without the GROUP BY clause and return only one row." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

[vector aggregates:] "When aggregate functions are used with the GROUP BY clause, they return values for each group. These are called vector aggregates." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A function applied to all of the rows in a table (producing a single value per function). An aggregate function in the select list with no GROUP BY clause applies to the whole table and is an example of a scalar." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[vector aggregate:] "Functions applied to all rows that have the same value in a specified column or expression by using the GROUP BY clause and, optionally, the HAVING clause (producing a value for each group per function)." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An aggregate value that is calculated on the data source. Depending on the data source, server aggregates can be treated as detail data or as aggregates based on the dataset option InterpretSubtotalsAsDetails." (Microsoft Technet)

[aggregate of aggregates:] "A summary value calculated from aggregates, such as the maximum of a set of sums." (Microsoft Technet)

 "An aggregate function, such as MIN(), MAX(), or AVG(), that is specified in a SELECT statement column list that contains only aggregate functions." (Microsoft Technet)

18 March 2009

DBMS: Data Independence (Definitions)

[logical *:] "Application programs and terminal activities remain logically unimpaired when information preserving changes of any kind that theoretically permit unimpairment are made to the base tables." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

[physical *]"Application programs and terminal activities remain logically unimpaired whenever any changes are made in either storage representation or access methods." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A condition that exists when data access is unaffected by changes in the physical data storage characteristics." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management 9th Ed", 2011)

"Data independence is the characteristic that enables data to be easily combined into usually unlimited number of different structures." (Michael M David & Lee Fesperman, "Advanced SQL Dynamic Data Modeling and Hierarchical Processing", 2013)

"A condition that exists when data access is unaffected by changes in the physical data storage characteristics." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management"  11th Ed., 2014)

"The isolation of data from the use of the data such that a change to one does not affect the other." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"Data independence is a database management system (DBMS) characteristic that lets programmers modify information definitions and organization without affecting the programs or applications that use it. Such property allows various users to access and process the same data for different purposes, regardless of changes made to it." (Techslang) [source]

"The property of being able to change the overall logical or physical structure of the data without changing the application program's view of the data." (GRC Data Intelligence)

"The degree to which the logical view of a database is immune to changes in the physical structure of the database." (IEEE 610.5-1990)

17 March 2009

DBMS: Aggregate Data (Definitions)

"A group such as grouped data. For example, when aggregating data, we are grouping data. A common aggregate function is Avg (average). It looks at a group of data (an aggregate) and provides an average." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"Data resulting from processes that combine and summarize atomic data." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

[aggregate:] "Pertaining to a combination of multiple values." (Microsoft, "SQL Server 2012 Glossary", 2012)

"Data that is the result of applying a process to combine data elements collectively or in summary form. The SQL SELECT List does this very easily and offers quite a bit of dynamic control." (Michael M David & Lee Fesperman, "Advanced SQL Dynamic Data Modeling and Hierarchical Processing", 2013)

[aggregate operation:] "An operation on a data structure as a whole, as opposed to an operation on an individual component of the data structure" (Nell Dale & John Lewis, "Computer Science Illuminated, 6th Ed.", 2015)

[aggregated data] "Refers to data that has been scrubbed of any personally or entity identifiable information and then generally combined with similar information from other parties." (James R Kalyvas & Michael R Overly, "Big Data: A Businessand Legal Guide", 2015)

"Structured data that results from applying a process to more detailed data - data that is summarized or averaged." (Ciara Heavin & Daniel J Power, "Decision Support, Analytics, and Business Intelligence" 3rd Ed., 2017)

[data aggregate] "A collection of two or more data items that are treated as a unit." (IEEE 610.5-1990)

16 March 2009

DBMS: SQL Injection (Definitions)

"SQL injection is a technique that exploits security vulnerabilities in the application layer and middle tier, allowing users to execute arbitrary SQL statements on a server." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"A security vulnerability that occurs in the persistence/database layer of a Web application. This vulnerability is derived from the incorrect escaping of variables embedded in SQL statements. It is in fact an instance of a more general class of vulnerabilities based on poor input validation and bad design that can occur whenever one programming or scripting language is embedded inside another." (Mark S Merkow & Lakshmikanth Raghavan, "Secure and Resilient Software Development", 2010)

"A form of Web hacking whereby SQL statements are specified in a Web form to expose data to the attacker." (Craig S Mullins, "Database Administration", 2012)

"SQL injection is a technique that exploits security vulnerabilities in the application layer and middle tier, allowing users to execute arbitrary SQL statements on a server." (Jay Natarajan et al, "Pro T-SQL 2012 Programmer's Guide 3rd Ed", 2012)

"The process of manipulating a web application to run SQL commands sent by an attacker." (Mark Rhodes-Ousley, "Information Security: The Complete Reference, Second Edition, 2nd Ed.", 2013)

"A technique that exploits security vulnerabilities in the application layer and middle tier, allowing users to execute arbitrary SQL statements on a server." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide 4th Ed", 2015)

DBMS: Hash Table (Definitions)

"A data structure used internally by Perl for implementing associative arrays (hashes) efficiently. See also bucket." (Jon Orwant et al, "Programming Perl" 4th Ed., 2012)

[hash cluster:] "A type of table cluster that is similar to an indexed cluster, except the index key is replaced with a hash function. No separate cluster index exists. In a hash cluster, the data is the index." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table." (Oracle, "Database SQL Tuning Guide Glossary", 2013)

"The data structure used to store elements using hashing" (Nell Dale et al, "Object-Oriented Data Structures Using Java" 4th Ed., 2016)

"An object that is like a dictionary or an associative array. A hash table stores and retrieves elements using key values called hashcodes. See also hashcode." (Daniel Leuck et al, "Learning Java" 5th Ed., 2020)

[sorted hash cluster:] "A hash cluster that stores the rows corresponding to each value of the hash function in such a way that the database can efficiently return them in sorted order. The database performs the optimized sort internally." (Oracle, "Oracle Database Concepts")

"An in-memory data structure that associates join keys with rows in a hash join. For example, in a join of the employees and departments tables, the join key might be the department ID. A hash function uses the join key to generate a hash value. This hash value is an index in an array, which is the hash table." (Oracle, "Oracle Database Concepts")

"A two-dimensional table of items in which a hash function is applied to the key of each item to determine its hash value. The hash value identifies each item's primary position in the table, and if this position is already occupied, the item is inserted either in an overflow table or in another available position in the table." (IEEE 610.5-1990)

DBMS: Hash Index (Definitions)

"A hashing algorithm is used to organize an index into a sequence, where each indexed value is retrievable based on the result of the hash key value. Hash indexes are efficient with integer values, but are usually subject to overflow as a result of changes." (Gavin Powell, "Beginning Database Design", 2006)

"An index based on an ordered list of hash values." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"An index based on an ordered list of hash values." (Carlos Coronel & Steven Morris, "Database Systems: Design, Implementation, & Management" 11th Ed., 2014)

 "A type of index intended for queries that use equality operators, rather than range operators such as greater-than or BETWEEN. It is available for MEMORY tables. Although hash indexes are the default for MEMORY tables for historic reasons, that storage engine also supports B-tree indexes, which are often a better choice for general-purpose queries. MySQL includes a variant of this index type, the adaptive hash index, that is constructed automatically for InnoDB tables if needed based on runtime conditions." (MySQL, "MySQL 8.0 Reference Manual Glossary")

[adaptive hash index:] "An optimization for InnoDB tables that can speed up lookups using - and IN operators, by constructing a hash index in memory. MySQL monitors index searches for InnoDB tables, and if queries could benefit from a hash index, it builds one automatically for index pages that are frequently accessed." (MySQL, "MySQL 8.0 Reference Manual Glossary")

"Hash indexes are file structures that can be used either to resolve queries by accessing the index instead of its underlying base table or to enhance access performance when they do not cover a query by providing a secondary access path to requested base table rows. They can either substitute for or point to base table rows." (Teradata)

DBMS: Query Plan (Definitions)

"The ordered set of steps required to carry out a query, complete with the access methods chosen for each table." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A portion of a DBMS that determines the most efficient sequence of relational algebra operations to use to satisfy a query." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The plan produced by an optimizer for processing a query." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A query plan is a sequence of logical and physical operators and data flows that the SQL query optimizer returns for use by the query processor to retrieve or modify data." (Michael Coles, "Pro T-SQL 2008 Programmer's Guide", 2008)

"Once the query optimizer determines the best way to execute a query, it creates a query plan. This identifies all the elements of the query, including what indexes are used, what types of joins are employed, and more." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A sequence of logical and physical operators and data flows that the SQL query optimizer returns for use by the query processor to retrieve or modify data." (Miguel Cebollero et al, "Pro T-SQL Programmer’s Guide" 4th Ed., 2015)

[adaptive query plan:] "An execution plan that changes after optimization because run-time conditions indicate that optimizer estimates are inaccurate. An adaptive query plan has different built-in plan options. During the first execution, before a specific subplan becomes active, the optimizer makes a final decision about which option to use. The optimizer bases its choice on observations made during the execution up to this point. Thus, an adaptive query plan enables the final plan for a statement to differ from the default plan." (Oracle)

[default plan:] "For an adaptive plan, the execution plan initially chosen by the optimizer using the statistics from the data dictionary. The default plan can differ from the final plan." (Oracle)

[execution plan:] "The combination of steps used by the database to execute a SQL statement. Each step either retrieves rows of data physically from the database or prepares them for the session issuing the statement." (Oracle)

[query execution plan:] "The set of decisions made by the optimizer about how to perform a query most efficiently, including which index or indexes to use, and the order in which to join tables." (MySQL)

DBMS: Network Model (Definitions)

[network database model:] "Essentially a refinement of the hierarchical database model. The network model allows child tables to have more than one parent, thus creating a networked-like table structure. Multiple parent tables for each child allow for many-to-many relationships, in addition to one-to-many relationships." (Gavin Powell, "Beginning Database Design", 2006)

[complex network data model:] "A navigational data model that supports direct many-to-many relationships." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

[simple network data model:] "A navigational data model that supports only one-to-many relationships but allows an entity to have an unlimited number of parent entities." (Jan L Harrington, "Relational Database Dessign: Clearly Explained" 2nd Ed., 2002)

[complex network data model:] "A navigational data model that permits direct many-to-many relationships as well as one-to-many and one-to-one relationships." (Jan L Harrington, "Relational Database Design and Implementation: Clearly explained" 3rd Ed., 2009)

[simple network data model:"A legacy data model where all relationships are one-to-many or one-toone; a navigational data model where relationships are represented with physical data structures such as pointers." (Jan L Harrington, "Relational Database Design and Implementation: Clearly explained" 3rd Ed., 2009)

"A data model standard created by the CODASYL Data Base Task Group in the late 1960s. It represented data as a collection of record types and relationships as predefined sets with an owner record type and a member record type in a 1:M relationship." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A DBMS architecture where record types are organized in a many-to-many structure consisting of multiple parent-child sets." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"A network model is a database model that is designed as a flexible approach to representing objects and their relationships. A unique feature of the network model is its schema, which is viewed as a graph where relationship types are arcs and object types are nodes." (Techopedia) [source]


15 March 2009

DBMS: Precision (Definitions)

"The maximum number of decimal digits that can be stored by numeric and decimal datatypes. The precision includes all digits, both to the right and to the left of the decimal point." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"The maximum total number of decimal digits that can be stored, both to the left and right of the decimal point." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The degree of detail used to state a numeric quantity; for example, writing a value to two decimal places instead of five decimal places. Contrast with accuracy." (Richard D Stutzke, "Estimating Software-Intensive Systems: Projects, Products, and Processes", 2005)

"This is the total number of digits that can be stored in an object that uses the decimal datatype." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"Refers to the preciseness with which a numerical quantity is expressed." (Michael Fitzgerald, "Learning Ruby", 2007)

"In a floating-point number, the number of digits to the right of the decimal point." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"The maximum number of significant digits that can be represented" (Nell Dale & John Lewis, "Computer Science Illuminated" 6th Ed., 2015)

"An attribute of a number that describes the total number of binary or decimal digits. An attribute of a timestamp that describes the total number of decimal digits in the fractional seconds part of the value." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

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]

14 March 2009

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)

13 March 2009

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)

12 March 2009

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)

10 March 2009

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)

09 March 2009

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,)

03 March 2009

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)

01 March 2009

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)

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