🛢DBMS: CRUD (Definitions)

"Create, Read, Update, and Delete. Refers to the major functions that need to be implemented in a database solution." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"Acronym for the four main database operations: Create, Read, Update, Delete. These operations correspond to the SQL statements INSERT, SELECT, UPDATE, and DELETE." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"An acronym for the fundamental operations of a database: Create, Read, Update, and Delete. See MongoDB CRUD Operations." (MongoDb, "Glossary", 2008)

"A list of the only functions of data in persistent storage, in a convenient acronym form." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"This acronym is commonly used to describe basic database functions." (Martin Oberhofer et al, "The Art of Enterprise Information Architecture", 2010)

"A current-state analysis exercise that inventories the systems, applications, and business processes that can create, read, update, and delete critical enterprise data and attributes. It's used to identify the processes and data access points that are affecting data quality or allowing improper usage of the data without suitable validation and governance." (Forrester)

"CRUD is an acronym that comes from the world of computer programming and refers to the four functions that are considered necessary to implement a persistent storage application: create, read, update and delete." (Sumo Logic) [source]

"CRUD (acronym for Create, Read, Update, Delete) are considered to be basic functions regarding stored data. In computer programming, possible actions are often mapped to these standard CRUD functions in order to clarify the actions. For example, standard HTTP(S) actions GET and POST refer to Read and Create functions regarding stored data." (Innopay)

🛢DBMS: Change Data Capture [CDC] (Definitions)

"As changes are made to a production data source, change data capture reads the source database log. This information can be used to prepare a batch to update the data warehouse, or it can update the data warehouse on a transaction-by-transaction basis. With SQL Server 7.0, transactional replication is an example of change data capture." (Microsoft Corporation, "Microsoft SQL Server 7.0 Data Warehouse Training Kit", 2000)

"The process of capturing changes made to a production data source. Change data capture is typically performed by reading the log file of the Database Management System of the source database. Change data capture consolidates units of work, ensures data is synchronized with the original source, and reduces data volume in a Data Warehousing environment." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The process of capturing changes made to a production data source; typically used in data warehousing environments." (Craig S Mullins, "Database Administration", 2012)

"Change data capture (CDC) is a set of software design patterns used to determine (and track) the data that has changed so that action can be taken using the changed data. CDC often uses the database transaction log to populate the deltas, although it can also query the database directly." (Piethein Strengholt, "Data Management at Scale", 2020)

"CDC is the process of capturing changes that were made in the source systems and applying these changes throughout the enterprise for both decision support systems such as information warehouse and operational data stores as well as other downstream consuming applications." (Saumya Chaki, "Enterprise Information Management in Practice", 2015)

"An automated approach for ensuring that data changes are synchronized across an enterprise by replicating data changes from a source system to other systems." (Jonathan Ferrar et al, "The Power of People", 2017)

🛢DBMS: Clustering (Definitions)

 "Technology that enables you to create a hot spare. That is a server that is actually running and can take over immediately. This technology enables you to mirror an entire server to another computer." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"The use of multiple computers to provide increased reliability, capacity, and management capabilities." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

[federated cluster:] "A grouping of SQL servers used together to achieve scalability by employing a distributed partition view. A federated cluster is not used for availability, only for achieving scalability through scale out." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"Any collection of distinct computers that are connected and used as a parallel computer, or to form a redundant system for higher availability. The computers in a cluster are not specialized to cluster computing and could, in principle, be used in isolation as standalone computers. In other words, the components making up the cluster, both the computers and the networks connecting them, are not custom-built for use in the cluster." (Beverly A Sanders, "Patterns for Parallel Programming", 2004)

"Connecting two or more computers in such a way that they behave like a single computer to an application or client. Clustering is used for parallel processing, load balancing, and fault tolerance." (Allan Hirt et al, "Microsoft SQL Server 2000 High Availability", 2004)

"A method of keeping database files physically close to one another on the storage media for improving performance through sequential pre-fetch operations." (Paulraj Ponniah, "Data Warehousing Fundamentals for IT Professionals", 2010)

"(1) The condition whereby data is physically ordered contiguously by a specified key (usually implemented by means of an index). (2) The use of multiple, 'independent' computing systems working together to form what appears to users as a single highly available system." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed, 2012)

"The tendency of elements to become unevenly distributed in the hash table, with many adjacent locations containing elements" (Nell Dale et al, "Object-Oriented Data Structures Using Java 4th Ed.", 2016)

🛢DBMS: Shared Lock (Definitions)

 "A lock created by non-update ('read') operations. Other users may read the data concurrently, but no transaction can acquire an exclusive lock on the data until all the shared locks have been released." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A lock used during READ operations." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"Lock that allows concurrent transactions to read a resource." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"Control over a portion of the database given to one or more transactions that prevents other transactions from modifying the data while the locks are in place." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"A lock on a database element that prevents other transactions from updating the database element while the lock is held." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A lock that is issued when a transaction requests permission to read data from a database and no exclusive locks are held on that data by another transaction. A shared lock allows other read-only transactions to access the database." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A lock created by non-update (read) operations." (SQL Server 2012 Glossary, "Microsoft", 2012)

"The type of lock taken by the DBMS when data is read with no intent to update it." (Craig S Mullins, "Database Administration", 2012)

"A lock that limits concurrently running application processes to read-only operations on database data." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Intent Lock (Definitions)

"Indicates the intention to acquire a share or exclusive lock on a data page." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Specifies the intent to gain a shared or exclusive lock." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An lock that indicates that SQL Server wants to acquire a shared or exclusive lock on a more specific resource. An intent lock prevents another transaction from acquiring an exclusive lock on the resource containing that page or row." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A lock of a larger object related to a locked small object. Implicitly, any small-grain lock implies a shared big-grain lock. If there is one or more locks on pages belonging to a table, then there will also be a lock on the table itself, as a separate lock record." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A lock placed on one level of a resource hierarchy to protect shared or exclusive locks on lower-level resources." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A lock on a resource that indicates that the holder of the lock will read (intent shared) or write (intent exclusive) the resource using concurrency control at a finer granularity than that of the resource with the intent lock. Intent locks allow concurrent readers and writers of a resource. See What type of locking does MongoDB use?." (MongoDb, "Glossary", 2008)

"A lock that is placed on one level of a resource hierarchy to protect shared or exclusive locks on lower-level resources." (SQL Server 2012 Glossary, "Microsoft", 2012)

"A type of lock placed on higher-level database objects when a user or process acquires locks on data pages or rows. An intent lock stays in place for the life of the lower-level locks." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed., 2012)

🛢DBMS: Query Optimizer (Definitions)

"SQL Server code that analyzes queries and database objects and selects the appropriate query plan. The SQL Server optimizer is a cost-based optimizer. It estimates the cost of each permutation of table accesses in terms of CPU cost and I/O cost." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A SQL server tool that formulates an optimum execution plan for a query." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"The SQL Server component responsible for generating the optimum execution plan for a query." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"The SQL Server database engine component responsible for generating efficient execution plans for SQL statements." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A term applied to a process, within a database engine, that attempts to find the fastest method of executing a SQL command against a database." (Gavin Powell, "Beginning Database Design", 2006)

"This is the component in SQL Server that analyzes your queries, compares them with available indexes, and decides which index will return a result set the fastest." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An optimization process running within SQL Server. Any queries submitted to SQL Server are first processed by the query optimizer. It determines the best way to run the query, including what indexes to use and what types of joins to use. The output is a query execution plan, sometimes called a query plan or just a plan." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"A process that generates query plans. For each query, the optimizer generates a plan that matches the query to the index that will return results as efficiently as possible. The optimizer reuses the query plan each time the query runs. If a collection changes significantly, the optimizer creates a new query plan." (MongoDb, "Glossary", 2008)

"The Optimizer is an internal technology that is responsible for selecting the most efficient means to accessing or altering information. It uses detailed statistics about the database to make the right decision." (Robert D Schneider & Darril Gibson, "Microsoft SQL Server 2008 All-in-One Desk Reference For Dummies", 2008)

"A part of a DBMS that examines a nonprocedural data manipulation request and makes a determination of the most efficient way to process that request." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"The component of a relational database system responsible for analyzing SQL queries and producing optimal access paths for retrieving data from the database." (Craig S Mullins, "Database Administration", 2012)

"A component of the SQL and XQuery compiler that chooses an access plan for a data manipulation language statement by modeling the execution cost of many alternative access plans and choosing the one with the minimal estimated cost." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Built-in database software that determines the most efficient way to execute a SQL statement by considering factors related to the objects referenced and the conditions specified in the statement." (Oracle)

"The MySQL component that determines the best indexes and join order to use for a query, based on characteristics and data distribution of the relevant tables." (MySQL)

🛢DBMS: Exclusive Locks (Definitions)

 "A lock that may not coexist with any other lock on the same object." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A lock used during WRITE operations." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A lock that prevents any other transaction from acquiring a lock on a resource until the original lock on the resource is released at the end of the transaction. An exclusive lock is always applied during an update operation (INSERT, UPDATE, or DELETE)." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"This type of lock prevents any other transaction from acquiring a lock on a resource until the original lock on the resource is released at the end of the transaction." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A lock on a database element that prevents other transactions from updating or viewing the database element while the lock is held." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"A lock that prevents any other transaction from acquiring a lock on a resource until the original lock on the resource is released at the end of the transaction." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The type of lock taken by the DBMS when data is modified to prohibit other processes or users from reading or modifying the same data." (Craig S Mullins, "Database Administration", 2012)

"A lock that prevents concurrently executing application processes from accessing database data. See also gross lock, shared lock." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Locks which prevent any other transaction from acquiring a lock until the original lock is released at the end of a transaction, always applied for update (insert, update, delete) operations." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

🛢DBMS: Deadlocks (Definitions)

 "A situation which arises when two users, each having a lock on one piece of data, attempt to acquire a lock on the other’s piece of data. The SQL Server detects deadlocks, and kills one user’s process." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"A situation that arises when two users, each having a lock on one piece of data, attempt to acquire a lock on the other’s piece. Each user waits for the other to release his or her lock. SQL Server detects deadlocks and kills one user’s process, returning error code 1205." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A condition that arises when two or more transactions are waiting for one another to release locks." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A situation in SQL Server 2000 when two users each have a lock on one piece of data and they attempt to acquire a lock on the other’s piece of data. Each user would wait indefinitely for the other to release the lock, unless one of the user processes is terminated. SQL Server detects deadlocks and terminates one user’s process." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A state in which two users or processes cannot continue processing because they each have a resource that the other needs." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"Occurs when multiple connections that hold locks are waiting for locks to be released that are held by the other transactions, that is, the transactions are waiting for each other to release locks." (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 specific type of locking problem when concurrent processes are competing for locks. For example, program1 holds a lock on A and is waiting for a lock on B; program2 holds a lock on B and is waiting for a lock on A." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed, 2012)

"A deadlock occurs when two or more user processes each have a lock on a separate page or table and each wants to acquire a lock on the other process’s page or table. The transaction with the least accumulated CPU time is killed and all of its work is rolled back." (Sybase)

"A situation in which two or more users are waiting for data locked by each other." (Oracle)

"A situation where different transactions are unable to proceed, because each holds a lock that the other needs. Because both transactions are waiting for a resource to become available, neither one ever releases the locks it holds." (MySQL)

"Unresolved contention for the use of resources." (IBM)

🛢DBMS: Lock/Locking (Definitions)

"The process of restricting access to resources in a multi-user environment to maintain security and prevent concurrent access problems. SQL Server automatically applies locks to tables or pages." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"SQL Server issues locks to prevent users from interfering with each other's work." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A restriction on access to a resource in a multiuser environment. SQL Server locks users out of a specific record, field, or file automatically to maintain security or prevent concurrent data manipulation problems." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A method the DBMS uses to prevent concurrent transactions from interfering with one another. Physically, a lock is one of three things: a latch, a mark on the wall, or a RAM record." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"A method of ensuring concurrency. Locking enables users to temporarily "check out" an object, preventing other users from changing the object, for the purpose of ensuring consistency." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"SQL Server uses locks to prevent multiple users from modifying the same data at the same time." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"A mechanism used by a concurrent system to prevent data anomalies by isolating transactions from each other." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A lock is an access restriction placed on part of a database to prevent other users or processes from viewing or modifying data as it is being viewed or modified by one process. Locks can be placed on rows, pages, extents, tables, or databases." (Darril Gibson, "MCITP SQL Server 2005 Database Developer All-in-One Exam Guide", 2008)

"MongoDB uses locks to ensure that concurrency does not affect correctness. MongoDB uses read locks, write locks and intent locks. For more information, see What type of locking does MongoDB use?." (MongoDb, "Glossary", 2008)

"Used to control access to part of the database. For example, while one user updates a row, the database places a lock on the row so other users cannot interfere with the update. Different databases may lock data by rows, table, or disk page." (Rod Stephens, "Beginning Database Design Solutions", 2008)

"The processing of giving a transaction exclusive rights to view and/or update a database element to prevent problems that arise with interleaved transaction execution." (Jan L Harrington, "SQL Clearly Explained 3rd Ed. ", 2010)

"A DBMS function used to ensure the integrity of data. When a database resource is locked by one process, another process is not permitted to change the locked data. Locking is necessary to enable the DBMS to facilitate the ACID properties of transaction processing." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed, 2012)

"A restriction on access to a resource in a multiuser environment." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A means of preventing uncommitted changes made by one application process from being perceived by another application process and for preventing one application process from updating data that is being accessed by another process. A lock ensures the integrity of data by preventing concurrent users from accessing inconsistent data. A means of serializing a sequence of events or serializing access to data." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"The process by which a DBMS restricts access to a row in a multiuser environment. The DBMS usually sets a bit on a row or the physical page containing a row that indicates the row or page is locked." (Microsoft) 

🛢DBMS: Base Table (Definitions)

"A table from which a view is derived. Also called an underlying table. A view can have one or more base tables or base views." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A table stored permanently in a database. Base tables are referenced by views, cursors, SQL statements, and stored procedures." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"Base table is a named relation corresponding to an entity in the conceptual schema, whose tuples (rows) are physically stored in the database." (S. Sumathi & S. Esakkirajan, "Fundamentals of Relational Database Management Systems", 2007)

"A relation whose contents are physically and permanently stored in a database." (Jan L Harrington, "SQL Clearly Explained" 3rd Ed., 2010)

"1.In Data Warehousing, the normalized data structures maintained in a Data Warehouse, in contrast to the de-normalized dependent data mart tables sourced from the base tables. 2.Outside of Data Warehousing, a table for an entity that is not dependent on any other entity in the database." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"The table on which a view is based." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed, 2011)

"A table stored permanently in a database. Base tables are referenced by views, cursors, SQL statements, and stored procedures." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A table that is created by the SQL CREATE TABLE statement and that holds persistent data. See also auxiliary table, created temporary table, declared temporary table, result table, table, temporary table, view." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

"Relations whose data are physically stored in a database." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The normalized data structures maintained in the target warehousing database. Also known as the detail data." (Sharon Allen & Evan Terry, "Beginning Relational Data Modeling" 2nd Ed., 2005)

🛢DBMS: Cascade/Cascading Delete (Definitions)

"When one delete causes a delete on another table, usually to enforce referential integrity." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A delete operation that deletes all related database rows or columns. Cascading deletes are typically implemented using triggers or stored procedures." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A deletion that triggers another deletion. A cascade delete may be specified for an entity bean with container-managed persistence." (Kim Haase et al, "The J2EE Tutorial", 2002)

"An operation that deletes a row containing a primary key value that is referenced by foreign key columns in existing rows in other tables." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

[cascading actions:] "Cascading delete or cascading update operations that either delete a row containing a Primary Key or updates a Primary Key value referenced by Foreign Key columns in existing rows in other tables. On a cascading delete, all the rows whose Foreign Key values reference the deleted Primary Key value are also deleted. On a cascading update, all the Foreign Key values are updated to match the new Primary Key value." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"A deletion that occurs when the deletion of a master record automatically deletes all child records in child-related tables, before deleting the record in the master table." (Gavin Powell, "Beginning Database Design", 2006)

"A delete operation of a row in a parent table that automatically deletes all related rows in the child table(s)." (Marilyn Miller-White et al, "MCITP Administrator: Microsoft® SQL Server™ 2005 Optimization and Maintenance 70-444", 2007)

"A referential integrity constraint on a foreign key that requires, upon deletion of a row in a table, deletion of any rows in other tables with foreign key values that point to the row in question." (David C Hay, "Data Model Patterns: A Metadata Map", 2010)

"The declaration made on a hierarchical (1:M) relationship between parent and child, that a request to delete a parent instance will also result in deleting the related child instances. Usually associated with a foreign key (which defines a hierarchical relationship), with the referring entity table (where the foreign key is stored) being the child and the referenced entity table is the parent." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"For relationships that enforce referential integrity between tables, the deletion of all related records in the related table or tables when a record in the primary table is deleted." (Microsoft, "SQL Server 2012 Glossary", 2012)

"A process by which the DB2 database manager enforces referential constraints by deleting all descendent rows of a deleted parent row." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

🛢DBMS: Cascading Update (Definitions)

"When one update causes an update on another table, usually to enforce referential integrity." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An update operation that updates all related database rows or columns. Cascading updates are typically implemented using triggers or stored procedures." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"An operation that updates a primary key value that is referenced by foreign key columns in existing rows in other tables." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"An update operation to a primary key value in the parent table that automatically updates all related foreign key values in the child table(s)." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"For relationships that enforce referential integrity between tables, the updating of all related records in the related table or tables when a record in the primary table is changed." (Microsoft, "SQL Server 2012 Glossary", 2012)

[cascading actions:] "Cascading delete or cascading update operations that either delete a row containing a Primary Key or updates a Primary Key value referenced by Foreign Key columns in existing rows in other tables. On a cascading delete, all the rows whose Foreign Key values reference the deleted Primary Key value are also deleted. On a cascading update, all the Foreign Key values are updated to match the new Primary Key value." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

🛢DBMS: Data Clustering (Definitions)

"A structure for storing data in a specific order; that is, an index that has data pages at the leaf layer. The main idea behind clusters is that all rows should be kept in order permanently according to some column value, such as the primary key." (Peter Gulutzan & Trudy Pelzer, "SQL Performance Tuning", 2002)

"The process of storing data (records) near each other on disk because they have the same or similar key values, to obtain maximum query efficiency. Clustering applies to indexes as well, to coordinate the fast access to clustered data on disk." (Sam Lightstone et al, "Physical Database Design: The Database Professional’s Guide to Exploiting Indexes, Views, Storage, and More", 2007)

"Physically storing foreign key rows close to the primary key rows they reference to improve database performance." (Jan L Harrington, "Relational Database Design and Implementation" 3rd Ed., 2009)

"The process of partitioning the data attributes of an entity or table into subsets or clusters of similar attributes, based on subject matter or characteristic (domain)." (DAMA International, "The DAMA Dictionary of Data Management", 2011)

"Placing one record occurrence on the same database page as another record occurrence so that the physical I/O to access one occurrence will also access the other occurrence. A common clustering strategy involves the parent-child binary relationship; the child record type occurrences are placed physically near the parent record type occurrence so that there is a significant chance that the physical I/O to access the parent will also access the child." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"Identifying groups of similar instances in a data set." (John D Kelleher & Brendan Tierney, "Data science", 2018)

🛢DBMS: Open Database Connectivity (Definitions)

"A set of drivers provided by different manufacturers that allows client applications to connect to database servers without regard to native database language. These drivers interpret data requests and translate those requests into a format that the database understands." (Patrick Dalton, "Microsoft SQL Server Black Book", 1997)

"A database-neutral API for Microsoft Windows applications. ODBC is designed to enable any database vendor to write a driver that supports the API." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"A database-material application programming interface (API) aligned with the American National Standards Institute (ANSI) and International Organization for Standardization (ISO) standards for a database call-level interface (CLI). ODBC supports access to any database for which an ODBC driver is available." (Microsoft Corporation, "SQL Server 7.0 System Administration Training Kit", 1999)

"A data access application programming interface (API) that supports access to any data source for which an ODBC driver is available. ODBC is aligned with the American National Standards Institute (ANSI) and International Organization for Standardization (ISO) standards for a database Call Level Interface (CLI)." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"A set of standards that allow applications that are not dependent on any one specific database to process SQL statements against any database that supports SQL." (Bob Bryla, "Oracle Database Foundations", 2004)

"A data access application programming interface (API) that supports access to any data source for which an ODBC driver is available. ODBC is aligned with the American National Standards Institute (ANSI) and International Standards Organization for (ISO) standards for a database Call Level Interface (CLI)." (Thomas Moore, "EXAM CRAM™ 2: Designing and Implementing Databases with SQL Server 2000 Enterprise Edition", 2005)

"Interface used to provide access to data sources that provide an ODBC driver. The driver is a software file that provides instructions for how to access the data source." (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 data access API that supports access to any data source for which an ODBC driver is available." (Jim Joseph, "Microsoft SQL Server 2008 Reporting Services Unleashed", 2009)

"Database middleware developed by Microsoft to provide a database access API to Windows applications." (Carlos Coronel et al, "Database Systems: Design, Implementation, and Management" 9th Ed., 2011)

"A call-level interface (CLI) for interacting with databases. ODBC provides routines to allocate and deallocate resources, control connections to the database, execute SQL statements, obtain diagnostic information, control transaction termination, and obtain information about the implementation." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed., 2012)

"A standard database access technology developed by Microsoft, the purpose of which is to allow accessing any DBMS from any application, regardless of which DBMS is managing the data." (Craig S Mullins, "Database Administration: The Complete Guide to DBA Practices and Procedures" 2nd Ed., 2012)

🛢DBMS: NoSQL (Definitions)

"An umbrella term for non-relational data stores, hence the name. These stores sacrifice ACID transactions for greater scalability and availability." (Dean Wampler, "Functional Programming for Java Developers", 2011)

"A set of technologies that created a broad array of database management systems that are distinct from relational database systems. One major difference is that SQL is not used as the primary query language. These database management systems are also designed for distributed data stores." (Marcia Kaufman et al, "Big Data For Dummies", 2013)

"A class of database management systems that consist of non-relational, distributed data stores. These systems are optimized for supporting the storage and retrieval requirements of massive-scale data-intensive applications." (IBM, "Informix Servers 12.1", 2014)

"A database that doesn’t adhere to relational database structures. Used to organize and query unstructured data." (Jason Williamson, "Getting a Big Data Job For Dummies", 2015)

"Any of a class of database management systems that reject the limitations and drawbacks dictated by, or associated with, the relational model. NoSQL products tend to specialize in a single or limited number of areas, such as high-performance processing, big data (giga-record systems), diverse data types (video, pictures, mathematical models), documents, and so on. Their specialized focus often requires deemphasizing other areas such as data consistency and backup and recovery." (George Tillmann, "Usage-Driven Database Design: From Logical Data Modeling through Physical Schmea Definition", 2017)

"In general, NoSQL databases provide a mechanism for storage and retrieval of data modeled in means other than the tabular relations used in relational databases." (Prashant Natarajan et al, "Demystifying Big Data and Machine Learning for Healthcare", 2017)

"NoSQL means 'not only SQL' or 'no SQL at all'. Being a new type of non-relational databases, NoSQL databases are developed for efficient and scalable management of big data." (Zongmin Ma & Li Yan, "Towards Massive RDF Storage in NoSQL Databases: A Survey", 2019)

"A broad term for a set of data access technologies that do not use the SQL language as their primary mechanism for reading and writing data. Some NoSQL technologies act as key-value stores, only accepting single-value reads and writes; some relax the restrictions of the ACID methodology; still others do not require a pre-planned schema." (MySQL, "MySQL 8.0 Reference Manual Glossary")

"A NoSQL database is distinguished mainly by what it is not - it is not a structured relational database format that links multiple separate tables. NoSQL stands for 'not only SQL', meaning that SQL, or structured query language is not needed to extract and organize information. NoSQL databases tend to be more diverse and flatter than relational databases (in a flat database, all data is contained in the same, large table)." (Statistics.com)

"NoSQL is a database management system built for the complexities of working with Big Data. Unlike SQL, NoSQL does not store data in a relational format." (Xplenty) [source]

"No-SQL (aka not only SQL) database systems are distributed, non-relational databases designed for large-scale data storage and for massively-parallel data processing across a large number of commodity servers." (IBM) 

"NoSQL is short for 'not only SQL'. NoSQL databases include mechanisms for storage and retrieval of data based on means other than the tabular relations used in relational databases." (Idera) [source]

"sometimes referred to as ‘Not only SQL’ as it is a database that doesn’t adhere to traditional relational database structures. It is more consistent and can achieve higher availability and horizontal scaling." (Analytics Insight)