Glossary of Terms

A | B | C | D | E | F | G | H | I | J | K | L |M | N | O | P | Q | R | S | T | U | V | W | XYZ  

A 

Aborted transaction:  A transaction in progress that terminates abnormally. (12)

Abstract class:  A class that has no direct instances, but whose descendants may have direct instances. (14)

Abstract operation:  Defines the form or protocol of the operation, but not its implementation. (14)

Action:  An operation, such as create, delete, update, or read, which may be performed on data objects. (4)

Action assertion:  A statement of a constraint or control on the actions of the organization. (4)

@ctive data warehouse:  An enterprise data warehouse that accepts near-real-time feeds of transactional data from the systems of record, analyzes warehouse data, and in near-real-time relays business rules to the data warehouse and systems of record so that immediate action can be taken in response to business events. (11)

ActiveX:  A loosely defined set of technologies developed by Microsoft that extends browser capabilities and allows the manipulation of data inside the browser. (10)

After-image:  A copy of a record (or page of memory) after it has been modified. (12)

Aggregation:  The process of transforming data from a detailed to a summary level. (11). A part-of relationship between a component object and an aggregate object. (14)

Alias:  An alternative name used for an attribute. (5)

Anchor object:  A business rule (a fact) on which actions are limited. (4)

Anomaly:  An error or inconsistency that may result when a user attempts to update a table that contains redundant data. The three types of anomalies are insertion, deletion, and modification. (5)

Application partitioning:  The process of assigning portions of application code to client or server partitions after it is written in order to achieve better performance and interoperability (ability of a component to function on different platforms). (9)

Application program interface (API):  Sets of routines that an application program uses to direct the performance of procedures by the computer's operating system. (9)

Array:  A dynamically sized ordered collection of elements that can be located by position. (15)

Association:  A named relationship between or among object classes. (14)

Association class:  An association that has attributes or operations of its own or that participates in relationships with other classes. (14)

Association role:  The end of an association where it connects to a class. (14)

Associative entity:  An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances. (3)

Asynchronous distributed database:  A form of distributed database technology in which copies of replicated data are kept at different nodes so that local servers can access data without reaching out across the network. (13)

Atomic literal:  A constant that cannot be decomposed into any further components. (15)

Attribute:  A property or characteristic of an entity type that is of interest to the organization. (3)

Attribute inheritance:  A property by which subtype entities inherit values of all attributes of the supertype. (4)

Authorization rules:  Controls incorporated in the data management systems that restrict access to data and also restrict the actions that people may take when they access data. (12)

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B 

Backup facilities:  A DBMS COPY utility that produces a backup copy (or save) of the entire database or a subset of the database. (12)

Backward recovery (rollback):  The back out, or undo, of unwanted changes to the database. Before-images of the records that have been changed are applied to the database, and the database is returned to an earlier state. Used to reverse the changes made by transactions that have been aborted or terminated abnormally. (12)

Bag:  An unordered collection of elements that may contain duplicates. (15)

Base table:  A table in the relational data model containing the inserted raw data. Base tables correspond to the relations that are identified in the database's conceptual schema. (7)

Before-image:  A copy of a record (or page of memory) before it has been modified. (12)

Behavior:  Represents how an object acts and reacts. (14)

Binary relationship:  A relationship between the instances of two entity types. (3)

Bitmap index:  A table of bits in which each row represents the distinct values of a key and each column is a bit, which when on indicates that the record for that bit column position has the associated field value. (6)

Blocking factor:  The number of physical records per page. (6)

Boyce-Codd normal form (BCNF):  A relation in which every determinant is a candidate key. (B)

Browser:  Software that displays HTML documents and allows users to access files and software related to the HTML documents. Browsers are based on the use of hyperlinks, which allow the user to jump to other documents by clicking on an object. Most also allow a user to download and transfer files, access newsgroups, play audio and video files, and execute small modules of code, such as Java applets or ActiveX controls. (10)

Business function:  A related group of business processes that support some aspect of the mission of an enterprise. (2)

Business rule:  A statement that defines or constrains some aspect of the business. It is intended to assert business structure or to control or influence the behavior of the business. (3)

Business-to-business (B2B):  Phrase used to describe electronic businesses that conduct e-commerce transactions with other businesses, including their suppliers and vendors. (10)

Business-to-consumer (B2C):  Phrase used to describe electronic businesses that conduct retail sales with consumers. (10)

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C 

Candidate key:  An attribute, or combination of attributes, that uniquely identifies a row in a relation. (5)

Cardinality constraint:  Specifies the number of instances of one entity that can (or must) be associated with each instance of another entity. (3)

Cascading Style Sheets (CSS):  Developed by the W3C, style sheets define the appearance of different elements and can be applied to any Web page. They are called cascading style sheets because more than one sheet can be applied to a Web page. (10)

Catalog:  A set of schemas that, when put together, constitute a description of a database. (7)

Checkpoint facility:  A facility by which the DBMS periodically refuses to accept any new transactions. The system is in a quiet state, and the database and transaction logs are synchronized. (12)

Class:  An entity that has a well-defined role in the application domain about which the organization wishes to maintain state, behavior, and identity. (14)

Class diagram:  Shows the static structure of an object-oriented model: the object classes, their internal structure, and the relationships in which they participate. (14)

Class-scope attribute:  An attribute of a class that specifies a value common to an entire class, rather than a specific value for an instance. (14)

Client/server architecture:  A LAN–based environment in which database software on a server (called a database server or database engine) performs database commands sent to it from client workstations, and application programs on each client concentrate on user interface functions. (2)

Client/server systems:  A networked computing model that distributes processes between clients and servers, which supply the requested services. In a database system, the database generally resides on a server that processes the DBMS. The clients may process the application systems or request services from another server that holds the application programs. (9)

ColdFusion Markup Language (CFML):  The language used to create ColdFusion application page scripts. The language is modeled after HTML and includes tags for performing operations such as reading and updating database tables. (10)

Collection literal:  A collection of literals or object types. (15)

Commit protocol:  An algorithm to ensure that a transaction is successfully completed or else it is aborted. (13)

Common Gateway Interface (CGI):  A Web server interface that specifies the transfer of information between a Web server and a CGI program. (10)

Completeness constraint:  A type of constraint that addresses the question whether an instance of a supertype must also be a member of at least one subtype. (4)

Composite attribute:  An attribute that can be broken down into component parts. (3)

Composite identifier:  An identifier that consists of a composite attribute. (3)

Composite key:  A primary key that consists of more than one attribute. (5)

Composition:  A part object that belongs to only one whole object and that lives and dies with the whole object. (14)

Computer-aided software engineering (CASE):  Software tools that provide automated support for some portion of the systems development process. (2)

Conceptual schema:  A detailed, technology-independent specification of the overall structure of organizational data. (2)

Concrete class:  A class that can have direct instances. (14)

Concurrency control:  The process of managing simultaneous operations against a database so that data integrity is maintained and the operations do not interfere with each other in a multiuser environment. (12)

Concurrency transparency:  A design goal for a distributed data- base, with the property that although a distributed system runs many transactions, it appears that a given transaction is the only activity in the system. Thus, when several transactions are processed concurrently, the results must be the same as if each transaction were processed in serial order. (13)

Conformed dimension:  One or more dimension tables associated with two or more fact tables for which the dimension tables have the same business meaning and primary key with each fact table. (11)

Constraint:  A rule that cannot be violated by database users. (1)

Constructor operation:  An operation that creates a new instance of a class. (14)

Content addressing:  The facility that allows a user to query a database to select all records and/or objects that satisfy a given set of qualifications. (D)

Cookie:  A block of data stored on a client by a Web server. When a user returns to a site, the contents of the cookie are sent back to the Web server and may be used to identify the user and return a customized Web page. (D)

Correlated subquery:  In SQL, a subquery in which processing the inner query depends on data from the outer query. (8)

Corresponding object:  A business rule (a fact) that influences the ability to perform an action on another business rule. (4)

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D 

Data:  Stored representations of objects and events that have meaning and importance in the user's environment. (1)

Data administration:  A high-level function that is responsible for the overall management of data resources in an organization, including maintaining corporate wide definitions and standards. (12)

Database:  An organized collection of logically related data. (1)

Database administration:  A technical function that is responsible for physical database design and for dealing with technical issues, such as security enforcement, database performance, and backup and recovery. (12)

Database application:  An application program (or set of related programs) that is used to perform a series of database activities (create, read, update, and delete) on behalf of database users. (1)

Database change log:  Before- and after-images of records that have been modified by transactions. (12)

Database destruction:  The database itself is lost or destroyed or cannot be read. (12)

Database Management System (DBMS):  A software system that is used to create, maintain, and provide controlled access to user databases. (1)

Database recovery:  Mechanisms for restoring a database quickly and accurately after loss or damage. (12)

Database security:  Protection of the data against accidental or intentional loss, destruction, or misuse. (12)

Database server:  A computer that is responsible for database storage, access, and processing in a client/server environment. Some people also use this term to describe a two-tier client/server environment. (9)

Data control language (DCL):  Commands used to control a database, including administering privileges and the committing (saving) of data. (7)

Data definition language (DDL):  Those commands used to define a database, including creating, altering, and dropping tables and establishing constraints. (7)

Data dictionary:  A repository of information about a database that documents data elements of a database. (12)

Data independence:  The separation of data descriptions from the application programs that use the data. (1)

Data manipulation language (DML):  Those commands used to maintain and query a database, including updating, inserting, modifying, and querying data. (7)

Data mart:  A data warehouse that is limited in scope, whose data are obtained by selecting and summarizing data from a data warehouse or from separate extract, transform, and load processes from source data systems. (11)

Data mining:  Knowledge discovery using a sophisticated blend of techniques from traditional statistics, artificial intelligence, and computer graphics. (11)

Data scrubbing:  A technique using pattern recognition and other artificial intelligence techniques to upgrade the quality of raw data before transforming and moving the data to the data warehouse. Also called data cleansing. (11)

Data steward:  A person assigned the responsibility of ensuring that organizational applications properly support the organization's enterprise goals for data quality. (12)

Data transformation:  The component of data reconciliation that converts data from the format of the source operational systems to the format of the enterprise data warehouse. (11)

Data type:  A detailed coding scheme recognized by system software, such as a DBMS, for representing organizational data. (6)

Data visualization:  The representation of data in graphical and multimedia formats for human analysis. (11)

Data warehouse:  An integrated decision support database whose content is derived from the various operational databases. (1). A subject-oriented, integrated, timevariant, nonupdatable collection of data used in support of management decision-making processes. (11)

DCS-1000 (Carnivore):  Device developed by the FBI to monitor e-mail traffic by tracking e-mail headers. (10)

Deadlock:  An impasse that results when two or more transactions have locked a common resource, and each waits for the other to unlock that resource. (12)

Deadlock prevention:  User programs must lock all records they require at the beginning of a transaction (rather than one at a time). (12)

Deadlock resolution:  An approach that allows deadlocks to occur but builds mechanisms into the DBMS for detecting and breaking the deadlocks. (12)

Decentralized database:  A database that is stored on computers at multiple locations; these computers are not interconnected by network and database software that make the data appear in one logical database. (13)

Degree:  The number of entity types that participate in a relationship. (3)

Denormalization:  The process of transforming normalized relations into unnormalized physical record specifications. (6)

Dependent data mart:  A data mart filled exclusively from the enterprise data warehouse and its reconciled data. (11)

Derivation:  A statement derived from other knowledge in the business. (4)

Derived attribute:  An attribute whose values can be calculated from related attribute values. (3)

Derived data:  Data that have been selected, formatted, and aggregated for end-user decision support applications. (11)

Derived fact:  A fact that is derived from business rules using an algorithm or inference. (4)

Determinant:  The attribute on the left-hand side of the arrow in a functional dependency. (5)

Dictionary:  An unordered sequence of key-value pairs without any duplicates. (15)

Disjointness constraint:  A constraint that addresses the question whether an instance of a supertype may simultaneously be a member of two (or more) subtypes. (4)

Disjoint rule:  Specifies that if an entity instance (of the supertype) is a member of one subtype, it cannot simultaneously be a member of any other subtype. (4)

Distributed database:  A single logical database that is spread physically across computers in multiple locations that are connected by a data communications link. (13)

DNS (domain name server) balancing:  A load-balancing approach where the DNS server for the hostname of the site returns multiple IP addresses for the site. (10)

Dynamic SQL:  The process of making an application capable of generating specific SQL code on the fly while the application is processing. (8)

Dynamic view:  A virtual table that is created dynamically upon request by a user. A dynamic view is not a temporary table. Rather, its definition is stored in the system catalog, and the contents of the view are materialized as a result of an SQL query that uses the view. It differs from a materialized view, which may be stored on a disk and refreshed at intervals or when used, depending on the RDBMS. (7)

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E 

Electronic business (e-business):  A technology-enabled business that uses Internet-related technology to facilitate the development of more integrated relationships with customers and suppliers. (10)

Electronic commerce (e-commerce):  Internet-based business transactions, including such activities as order processing and fulfillment, customer relationship management interactions, electronic data interchange (EDI), and bill payments. (10)

Embedded SQL:  The process of including hard-coded SQL statements in a program written in another language, such as C or Java. (8)

Encapsulation:  The technique of hiding the internal implementation details of an object from its external view. (14)

Encryption:  The coding or scrambling of data so that humans cannot read them. (12)

Enhanced entity-relationship (EER) model:  The model that has resulted from extending the original E-R model with new modeling constructs. (4)

Enterprise data model:  A graphical model that shows the high-level entities for the organization and the relationships among those entities. (1)

Enterprise data modeling:  The first step in database development, in which the scope and general contents of organizational databases are specified. (2)

Enterprise data warehouse (EDW):  A centralized, integrated data warehouse that is the control point and single source of all data made available to end users for decision support applications. (11)

Enterprise key:  A primary key whose value is unique across all relations. (5)

Enterprise resource planning (ERP) systems:  A business management system that integrates all functions of the enterprise, such as manufacturing, sales, finance, marketing, inventory, accounting, and human resources. ERP systems are software applications that provide the data necessary for the enterprise to examine and manage its activities. (1)

Entity:  A person, place, object, event, or concept in the user environment about which the organization wishes to maintain data. (3)

Entity cluster:  A set of one or more entity types and associated relationships grouped into a single abstract entity type. (4)

Entity instance:  A single occurrence of an entity type. (3)

Entity integrity rule:  No primary key attribute (or component of a primary key attribute) can be null. (5)

Entity-relationship diagram (E-R diagram):  A graphical representation of an entity-relationship model. (3)

Entity-relationship model (E-R model):  A logical representation of the data for an organization or for a business area. (3)

Entity type:  A collection of entities that share common properties or characteristics. (3)

Equi-join:  A join in which the joining condition is based on equality between values in the common columns. Common columns appear (redundantly) in the result table. (8)

Event:  A database action (create, update, or delete) that results from a transaction. (11)

Event driven:  Nonprocedural programming that detects an event when it occurs and generates an appropriate response to that event. (9)

Exclusive lock (X lock or write lock):  A technique that prevents another transaction from reading and therefore updating a record until it is unlocked. (12)

Extensible Markup Language (XML):  A scripting language based on SGML that allows the creation of customized tags, which enable easier transmission and sharing of data across organizations. (10)

Extent:  Relates to physical database design. A contiguous section of disk storage space. (6). Relates to object-oriented databases. The set of all instances of a class within the database. (15)

Extranet:  Use of Internet protocols to establish limited access to company data and information by the company's customers and suppliers. (1)

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F 

Fact:  An association between two or more terms. (3)

Failure transparency:  A design goal for a distributed database, which guarantees that either all the actions of each transaction are committed or else none of them is committed. (13)

Fat client:  A client PC that is responsible for processing presentation logic, extensive application and business rules logic, and many DBMS functions. (9)

Field:  The smallest unit of named application data recognized by system software. (6)

File organization:  A technique for physically arranging the records of a file on secondary storage devices. (6)

File server:  A device that manages file operations and is shared by each of the client PCs attached to the LAN. (9)

Firewall:  A hardware/software security component that limits external access to company data. (10)

First normal form:  A relation that has a primary key and in which there are no repeating groups. (5)

Foreign key:  An attribute in a relation of a database that serves as the primary key of another relation in the same database. (5)

Forward recovery (rollforward):  A technique that starts with an earlier copy of the database. After-images (the results of good transactions) are applied to the database, and the database is quickly moved forward to a later state. (12)

Fourth normal form (4NF):  A relation in BCNF that contains no multivalued dependencies. (B)

Function:  A stored subroutine that returns one value and has only input parameters. (8)

Functional decomposition:  An iterative process of breaking down the description of a system into finer and finer detail in which one function is described in greater detail by a set of other, supporting functions. (2)

Functional dependency:  A constraint between two attributes or two sets of attributes. (5)

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G 

Generalization:  The process of defining a more general entity type from a set of more specialized entity types. (4)

Global transaction:  In a distributed database, a transaction that requires reference to data at one or more nonlocal sites to satisfy the request. (13)

Grain:  The level of detail in a fact table determined by the intersection of all the components of the primary key, including all foreign keys and any other primary key elements. (11)

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H 

Hashed file organization:  A storage system in which the address for each record is determined using a hashing algorithm. (6)

Hash index table:  A file organization that uses hashing to map a key into a location in an index, where there is a pointer to the actual data record matching the hash key. (6)

Hashing algorithm:  A routine that converts a primary key value into a relative record number (or relative file address). (6)

Homonym:  An attribute that may have more than one meaning. (5)

Horizontal partitioning:  Distributing the rows of a table into several separate files. (6)

Hypertext Markup Language (HTML):  The scripting language used for documents displayed through browsers on the Web. HTML is similar to SGML, which is a more comprehensive information management standard. (10)

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I 

Identifier:  An attribute (or combination of attributes) that uniquely identifies individual instances of an entity type. (3)

Identifying owner (owner):  The entity type on which the weak entity type depends. (3)

Identifying relationship:  The relationship between a weak entity type and its owner. (3)

Inconsistent read problem:  An unrepeatable read, one that occurs when one user reads data that have been partially updated by another user. (12)

Incremental commitment:  A strategy in systems development projects in which the project is reviewed after each phase and continuation of the project is rejustified in each of these reviews. (2)

Incremental extract:  A method of capturing only the changes that have occurred in the source data since the last capture. (11)

Independent data mart:  A data mart filled with data extracted from the operational environment, without benefit of a data warehouse. (11)

Index:  A table or other data structure used to determine the location of rows in a file that satisfy some condition. (6)

Indexed file organization:  The storage of records either sequentially or nonsequentially with an index that allows software to locate individual records. (6)

Information:  Data that have been processed in such a way as to increase the knowledge of the person who uses the data. (1)

Information engineering:  A formal, top-down methodology that uses a data orientation to create and maintain information systems. (2)

Information repository:  A component that stores metadata that describe an organization's data and data processing resources, manages the total information processing environment, and combines information about an organization's business information and its application portfolio. (12)

Information Repository Dictionary System (IRDS):  A computer software tool that is used to manage and control access to the information repository. (12)

Information systems architecture (ISA):  A conceptual blueprint or plan that expresses the desired future structure for the information systems in an organization. (2)

Informational systems:  Systems designed to support decision making based on historical point-in-time and prediction data for complex queries or data mining applications. (11)

Intranet:  Use of Internet protocols to establish access to company data and information that is limited to the organization. (1)

Intrusion detection system (IDS):  A system that tries to identify attempts to hack or break into a computer system or to misuse it. IDSs may monitor packets passing over the network, monitor system files, monitor log files, or set up deception systems that attempt to trap hackers. (10)

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J 

Java:  A general-purpose, object-oriented programming language that is well suited for use on the Web. Small Java programs, called Java applets, download from a Web server to the client and run in a Java-compatible Web browser. (10)

JavaScript:  A scripting language based on Java, but easier to learn, that is used to achieve interactivity on Web pages. (10)

Java servlet:  A small program that executes from within another application rather than from the operating system and is stored on the server rather than with an application on a client. (10)

Join:  A relational operation that causes two tables with a common domain to be combined into a single table or view. (8)

Join index:  An index on columns from two or more tables that come from the same domain of values. (6)

Joining:  The process of combining data from various sources into a single table or view. (11)

Journalizing facilities:  An audit trail of transactions and database changes. (12)

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K 

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L 

Legacy data:  Data contained by a system used prior to the installation of a new system. Legacy data often reside on mainframe systems, which may have been replaced by client/server systems or Web-enabled systems. (1)

List:  An ordered collection of elements of the same type. (15)

Local autonomy:  A design goal for a distributed database, which says that a site can independently administer and operate its database when connections to other nodes have failed. (13)

Local transaction:  In a distributed database, a transaction that requires reference only to data that are stored at the site where the transaction originates. (13)

Location transparency:  A design goal for a distributed database, which says that a user (or user program) using data need not know the location of the data. (13)

Locking:  Any data that are retrieved by a user for updating must be locked, or denied to other users, until the update is completed or aborted. (12)

Locking level (lock granularity):  The extent of the database resource that is included with each lock. (12)

Logical data mart:  A data mart created by a relational view of a data warehouse. (11)

Logical schema:  The representation of a database for a particular data management technology. (2)

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M 

Market basket analysis:  The study of buying behavior of individual customers. (11)

Massively parallel processing (MPP)/shared nothing architecture:  Massively parallel processing systems in which each CPU has its own dedicated memory. (9)

Materialized view:  Copies or replicas of data based on SQL queries created in the same manner as dynamic views. However, a materialized view exists as a table and thus care must be taken to keep it synchronized with its associated base tables. (7)

Maximum cardinality:  The maximum number of instances of one entity that may be associated with each instance of another entity. (3)

Metadata:  Data that describe the properties or characteristics of end-user data and the context of that data. (1)

Method:  The implementation of an operation. (14)

Middleware:  Software that allows an application to interoperate with other software without requiring the user to understand and code the low-level operations necessary to achieve interoperability. (9)

Minimum cardinality:  The minimum number of instances of one entity that may be associated with each instance of another entity. (3)

Multidimensional OLAP (MOLAP):  OLAP tools that load data into an intermediate structure, usually a three- or higher-dimensional array. (11)

Multiple classification:  An object is an instance of more than one class. (14)

Multiplicity:  A specification that indicates how many objects participate in a given relationship. (14)

Multivalued attribute:  An attribute that may take on more than one value for a given entity instance. (3)

Multivalued dependency:  The type of dependency that exists when there are at least three attributes (e.g., A, B, and C) in a relation, with a well-defined set of B and C values for each A value, but those B and C values are independent of each other. (B)

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N 

Natural join:  Same as equi-join except one of the duplicate columns is eliminated in the result table. (8)

Normal form:  A state of a relation that results from applying simple rules regarding functional dependencies (or relationships between attributes) to that relation. (5)

Normalization:  The process of decomposing relations with anomalies to produce smaller, well-structured relations. (5)

Null:  A value that may be assigned to an attribute when no other value applies or when the applicable value is un-known. (5)

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O 

Object:  An instance of a class that encapsulates data and behavior. (14)

Object diagram:  A graph of instances that are compatible with a given class diagram. (14)

Object-relational database management system (ORDBMS):  A database engine that supports both relational and object-oriented features in an integrated fashion. (D)

On-line analytical processing (OLAP):  The use of a set of graphical tools that provides users with multidimensional views of their data and allows them to analyze the data using simple windowing techniques. (11)

Open database connectivity (ODBC) standard:  An application programming interface that provides a common language for application programs to access and process SQL databases independent of the particular RDBMS that is accessed. (9)

Open-source DBMS:  Free DBMS source code software that provides the core functionality of an SQL-compliant DBMS. (12)

Operation:  A function or a service that is provided by all the instances of a class. (14)

Operational data store (ODS):  An integrated, subject-oriented, updatable, current-valued, enterprisewide, detailed database designed to serve operational users as they do decision support processing. (11)

Operational system:  A system that is used to run a business in real time based on current data. Also called system of record. (11)

Optional attribute:  An attribute of an entity that may not have a value for every entity instance. (3)

Outer join:  A join in which rows that do not have matching values in common columns are nevertheless included in the result table. (8)

Overlap rule:  Specifies that an entity instance can simultaneously be a member of two (or more) subtypes. (4)

Overriding:  The process of replacing a method inherited from a superclass by a more specific implementation of that method in a subclass. (14)

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P 

Page:  The amount of data read or written by an operating system in one secondary memory (disk) input or output (I/O) operation. For I/O with a magnetic tape, the equivalent term is record block. (6)

Partial functional dependency:  A functional dependency in which one or more nonkey attributes are functionally dependent on part (but not all) of the primary key. (5)

Partial specialization rule:  Specifies that an entity instance of the supertype is allowed not to belong to any subtype. (4)

Periodic data:  Data that are never physically altered or deleted once they have been added to the store. (11)

Persistent Stored Modules (SQL/PSM):  Extensions defined in SQL-99 that include the capability to create and drop modules of code stored in the database schema across user sessions. (8)

Physical file:  A named portion of secondary memory (a magnetic tape or hard disk) allocated for the purpose of storing physical records. (6)

Physical record:  A group of fields stored in adjacent memory locations and retrieved and written together as a unit by a DBMS. (6)

Physical schema:  Specifications for how data from a logical schema are stored in a computer's secondary memory by a database management system. (2)

Plug-ins:  Hardware or software modules that extend the capabilities of a browser by adding a specific feature, such as encryption, animation, or wireless access. (10)

Pointer:  A field of data that can be used to locate a related field or record of data. (6)

Polymorphism:  The same operation may apply to two or more classes in different ways. (14)

Primary key:  An attribute (or combination of attributes) that uniquely identifies each row in a relation. (5)

Procedure:  A collection of procedural and SQL statements that are assigned a unique name within the schema and stored in the database. (8)

Project:  A planned undertaking of related activities to reach an objective that has a beginning and an end. (2)

Prototyping:  An iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users. (2)

Proxy server:  A firewall component that manages Internet traffic to and from a LAN. It can also handle access control and document caching. (10)

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Q 

Query-by-Example (QBE):  A direct-manipulation database language that uses a graphical approach to query construction. (9)

Query operation:  An operation that accesses the state of an object but does not alter the state. (14)

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R 

Reconciled data:  Detailed, current data intended to be the single, authoritative source for all decision support applications. (11)

Recovery manager:  A module of the DBMS that restores the database to a correct condition when a failure occurs and then resumes processing user requests. (12)

Recursive foreign key:  A foreign key in a relation that references the primary key values of that same relation. (5)

Redundant Array of Inexpensive Disks (RAID):  A set, or array, of physical disk drives that appear to the database user (and programs) as if they form one large logical storage unit. (6)

Referential integrity:  An integrity constraint specifying that the value (or existence) of an attribute in one relation depends on the value (or existence) of a primary key in the same or another relation. (7)

Referential integrity constraint:  A rule that states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null. (5)

Refresh mode:  An approach to filling the data warehouse that employs bulk rewriting of the target data at periodic intervals. (11)

Relation:  A named two-dimensional table of data. (5)

Relational DBMS (RDBMS):  A database management system that manages data as a collection of tables in which all data relationships are represented by common values in related tables. (7)

Relational OLAP (ROLAP):  OLAP tools that view the database as a traditional relational database in either a star schema or other normalized or denormalized set of tables. (11)

Relationship instance:  An association between (or among) entity instances where each relationship instance includes exactly one entity from each participating entity type. (3)

Relationship type:  A meaningful association between (or among) entity types. (3)

Replication transparency:  A design goal for a distributed database, which says that although a given data item may be replicated at several nodes in a network, a programmer or user may treat the data item as if it were a single item at a single node. Also called fragmentation transparency. (13)

Repository:  A centralized knowledge base of all data definitions, data relationships, screen and report formats, and other system components. (1)

Required attribute:  An attribute of an entity that must have a value for each entity instance. (3)

Restore/rerun:  A technique that involves reprocessing the day's transactions (up to the point of failure) against the backup copy of the database. (12)

Reverse proxy:  A load-balancing approach that intercepts requests from clients and caches the response on the Web server that sends it back to the client. (10)

Router:  An intermediate device on a communications network used to transmit message packets and forward them to the correct destination over the most efficient pathway. (10)

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S 

Scalar aggregate:  A single value returned from an SQL query that includes an aggregate function. (7)

Schema:  The structure that contains descriptions of objects created by a user, such as base tables, views, and constraints, as part of a database. (7)

Scope operation:  An operation that applies to a class rather than an object instance. (14)

Secondary key:  One field or a combination of fields for which more than one record may have the same combination of values. Also called a nonunique key. (6)

Second normal form:  A relation in first normal form in which every nonkey attribute is fully functionally dependent on the primary key. (5)

Selection:  The process of partitioning data according to predefined criteria. (11)

Semijoin:  A joining operation used with distributed databases in which only the joining attribute from one site is transmitted to the other site, rather than all the selected attributes from every qualified row. (13)

Sequential file organization:  The storage of records in a file in sequence according to a primary key value. (6)

Server-side extension:  A software program that interacts directly with a Web server to handle requests. (10)

Set:  An unordered collection of elements without any duplicates. (15)

Shared lock (S lock or read lock):  A technique that allows other transactions to read but not update a record or other resource. (12)

Simple (or atomic) attribute:  An attribute that cannot be broken down into smaller components. (3)

Simple Object Access Protocol (SOAP):  An XML-based communication protocol used for sending messages between applications via the Internet. (10)

Smart card:  A credit-card-sized plastic card with an embedded microprocessor chip with the ability to store, process, and output electronic data in a secure manner. (12)

Snowflake schema:  An expanded version of a star schema in which dimension tables are normalized into several related tables. (11)

Software and hardware load balancing:  A load-balancing approach where requests to one IP address are distributed among the multiple servers hosting the Website at the TCP/IP routing level. (10)

Specialization:  The process of defining one or more subtypes of the supertype and forming supertype/subtype relationships. (4)

Standard Generalized Markup Language (SGML):  An information-management standard adopted in 1986 by the International Organization for Standardization to script documents so that formatting, indexing, and linked information is defined across platforms and applications. (10)

Star schema:  A simple database design in which dimensional data are separated from fact or event data. A dimensional model is another name for star schema. (11)

State:  Encompasses an object's properties (attributes and relationships) and the values those properties have. (14)

Static extract:  A method of capturing a snapshot of the required source data at a point in time. (11)

Stored procedure:  A module of code, usually written in a proprietary language such as Oracle's PL/SQL or Sybase's Transact-SQL, that implements application logic or a business rule and is stored on the server, where it runs when it is called. (9)

Stripe:  The set of pages on all disks in a RAID that are the same relative distance from the beginning of the disk drive. (6)

Strong entity type:  An entity that exists independently of other entity types. (3)

Structural assertion:  A statement that expresses some aspect of the static structure of the organization. (4)

Structured literal:  A fixed number of named elements, each of which could be of literal or object type. (15)

Subtype:  A subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroupings. (4)

Subtype discriminator:  An attribute of the supertype whose values determine the target subtype or subtypes. (4)

Supertype:  A generic entity type that has a relationship with one or more subtypes. (4)

Supertype/subtype hierarchy:  A hierarchical arrangement of supertypes and subtypes, where each subtype has only one supertype. (4)

Symmetric multiprocessing (SMP):  A parallel processing architecture where the processors share a common shared memory. (9)

Synchronous distributed database:  A form of distributed database technology in which all data across the network are continuously kept up-to-date so that a user at any site can access data anywhere on the network at any time and get the same answer. (13)

Synonyms:  Two (or more) attributes having different names but the same meaning, as when they describe the same characteristic of an entity. (5)

System catalog:  A system-created database that describes all database objects, including data dictionary information, and also includes user access information. (12)

Systems development life cycle (SDLC):  The traditional methodology used to develop, maintain, and replace information systems. (2)

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T 

Tablespace:  A named set of disk storage elements in which physical files for database tables may be stored. (6)

Term:  A word or phrase that has a specific meaning for the business. (3)

Ternary relationship:  A simultaneous relationship among the instances of three entity types. (3)

Thin client:  A PC configured for handling user interfaces and some application processing, usually with no or limited local data storage. (9)

Third normal form:  A relation that is in second normal form and has no transitive dependencies present. (5)

Three-tier architecture:  A client/server configuration that includes three layers: a client layer and two server layers. Although the nature of the server layers differs, a common configuration contains an application server. (9)

Time stamp:  A time value that is associated with a data value. (3)

Timestamping:  In distributed databases, a concurrency control mechanism that assigns a globally unique timestamp to each transaction. Timestamping is an alternative to the use of locks in distributed databases. (13)

Top-down planning:  A generic information systems planning methodology that attempts to gain a broad understanding of the information system needs of the entire organization. (2)

Total specialization rule:  Specifies that each entity instance of the supertype must be a member of some subtype in the relationship. (4)

Transaction:  A discrete unit of work that must be completely processed or not processed at all within a computer system. Entering a customer order is an example of a transaction. (12)

Transaction boundaries:  The logical beginning and end of transactions. (12)

Transaction log:  A record of the essential data for each transaction that is processed against the database. (12)

Transaction manager:  In a distributed database, a software module that maintains a log of all transactions and an appropriate concurrency control scheme. (13)

Transient data:  Data in which changes to existing records are written over previous records, thus destroying the previous data content. (11)

Transitive dependency:  A functional dependency between two (or more) nonkey attributes. (5)

Trigger:  A named set of SQL statements that is considered (triggered) when a data modification (INSERT, UPDATE, DELETE) occurs. If a condition stated within the trigger is met, then a prescribed action is taken. (8)

Two-phase commit:  An algorithm for coordinating updates in a distributed database. (13)

Two-phase locking protocol:  A procedure for acquiring the necessary locks for a transaction where all necessary locks are acquired before any locks are released, resulting in a growing phase, when locks are acquired, and a shrinking phase, when they are released. (12)

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U 

Unary relationship:  A relationship between the instances of a single entity type. (3)

Universal Description, Discovery, and Integration (UDDI):  A technical specification for creating a distributed registry of Web services and businesses that are open to communicating through Web services. (10)

Update mode:  An approach in which only changes in the source data are written to the data warehouse. (11)

Update operation:  An operation that alters the state of an object. (14)

User-defined data type (UDT):  SQL-99 allows users to define their own data type by making it a subclass of a standard type or creating a type that behaves as an object. UDTs may also have defined functions and methods. (8)

User-defined procedures:  User exits (or interfaces) that allow system designers to define their own security procedures in addition to the authorization rules. (12)

User view:  A logical description of some portion of the database that is required by a user to perform some task. (1)

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V 

VBScript:  A scripting language based on Microsoft Visual Basic and similar to JavaScript. (10)

Vector aggregate:  Multiple values returned from an SQL query that includes an aggregate function. (7)

Versioning:  Each transaction is restricted to a view of the database as of the time that transaction started, and when a transaction modifies a record, the DBMS creates a new record version instead of overwriting the old record. Hence, no form of locking is required. (12)

Vertical partitioning:  Distributing the columns of a table into several separate physical records. (6)

Visual Basic for Applications (VBA):  The programming language that accompanies Microsoft Access 2002. (9)

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W 

Weak entity type:  An entity type whose existence depends on some other entity type. (3)

Web services:  Set of emerging standards that define protocols for automatic communication between software programs over the Web. Web services are XML-based and usually run in the background to establish transparent communication among computers. (10)

Web Services Description Language (WSDL):  An XML-based grammar or language used to describe a Web service and specify a public interface for that service. (10)

Well-structured relation:  A relation that contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies. (5)

World Wide Web (WWW):  The total set of interlinked hypertext documents residing on special servers, called Web servers or HTTP servers, worldwide. The Web servers are configured to make the information they hold easily accessible to each other and to allow files to be accessed, transferred, and downloaded. Also referred to as W3 or the Web. (10)

World Wide Web Consortium (W3C):  An international consortium of companies working to develop open standards that foster the development of Web conventions so that Web documents can be consistently displayed across all platforms. (10)

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XYZ 

XHTML:  A hybrid scripting language that extends HTML code to make it XML compliant. (10)

XSL:  A language used to develop style sheets. An XSL style sheet is similar to CSS but describes how an XML document will be displayed. (10)

XSLT:  Language used to transform complex XML documents and also used to create HTML pages from XML documents. (10)

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