Glossary

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Contents: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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A

Active File Directory

The Active File Directory is the directory in which files checked out from the Repository are placed.

Aggregation

The process of combining several objects into one.

Alias

An alternate name for an attribute or column.

Alternate Key

One or more attributes that can uniquely identify entity members. It is a candidate key that has not been chosen as the primary key.

Ancestor

An entity that contributes one or more primary key attributes to another entity, either directly as the parent or indirectly through one or more child entities.

Associate Entity

An entity that inherits its primary key from more than one entity.

Attribute

A relevant property or characteristic of an entity. In the physical design, attributes are represented as table columns.

Auxiliary Table

Table that stores the data of LOB Columns.


B

Base Attribute

The underlying attribute for which a role name has been defined.

Biconnected

A graph is considered biconnected if within that graph, when any entity is deleted the graph remains completely connected. In deciding how to circularly layout the target diagram.

Buffer Pool

An area of storage where data is cached in memory.

Business Rule

A business policy or guideline that can be enforced through a data model.


C

Candidate Key

One or more attributes that can uniquely identify each instance of an entity.

Cardinality

In a relationship, the ratio of related parent and child entity instances.

Cascade

A process that ensures that the deletion or update of an entity instance is propagated to dependent instances in other entities.

Check Constraint

A database feature that validates the value of one or more table columns. It enforces data integrity by requiring data to fulfill certain conditions.

Child Entity

An entity that inherits a foreign key from another entity.

Cluster

Diagram auto-layout term. A group of related entities.

Column

A column represents a relevant property or characteristic of a table. Columns correspond to attributes in the logical model.

Common Ancestor

An entity that contributes its primary key to another entity along several different relationship paths.

Compound Key

A primary key that consists of more than one attribute, some of which can be inherited as foreign keys from other entities.

Composite Key

A primary key that consists of more than one attribute, some of which can be inherited as foreign keys from other entities.

Conceptual Schema

The logical design of a data model presented in a form independent of any physical database design or external presentation format.

Constraint

A mechanism for maintaining valid data values.


D

Database

An organized collection of data stored in tables.

Data Attribute

An attribute that is not part of an entity's primary key.

Data Definition Language (DDL)

The language and syntax for a given DBMS used to create, modify and drop database objects.

Data Dictionary

Organized metadata describing the structure and properties of a data model.

Data Model

A logical specification for the data structures and business rules governing a business area.

Data Object

An entity or attribute.

Data Source

  1. A database table, flat file, XML file, JMS stream, or SAP BAPI used as a source or target by an ER/Studio Data Architect task.
  2. An object in an ER/Studio Data Architect model that represents such a Data Source.
  3. An object in a an ER/Studio Data Architect task that represents such a Data Source. To avoid confusion, in this document we generally refer to (3) as a source (if the task reads the Data Source) or a target (if the task writes to the Data Source).

Datatype

A form of data can be stored in a database.

Default

A value supplied to an attribute or table column when none is specified by the modeler.

Definition Dependency

When the definition of an attribute depends on the value of some other attribute. This condition violates the precepts of normalization and is highly undesirable.

Denormalization

The intentional modification of a data model to a lower-level normal form. Denormalization is usually undertaken to achieve improved performance in implementing a physical design.

Dependent Entity

An entity is a dependent entity when its primary key contains foreign keys.

Derived Attribute

An attribute whose value can be determined from the values of other attributes.

Descendent

An entity that receives some or all of its primary keys as foreign keys from other entities.

Descriptor

A non-key attribute or column.

Determinant

An attribute or group attribute on which another attribute is fully functionally dependent.

Diagram

The data model in its entirety, including its logical and physical designs.

Discriminator

An attribute of a supertype that distinguishes general differences between associated subtypes.

Document Type Definition (DTD)

The Document Type Definition (DTD) is another XML schema language. The DTD is a description in XML Declaration Syntax of a particular type or class of documents. It defines what names are used for certain element type, where they may occur, and how the elements fit together and ensures that all documents conforming to the DTD are constructed and named in a consistent manner. Validators in applications such as editors, search engines, browsers, and databases can read the DTD before reading the XML file in order to prepare to display or otherwise work with the XML document.

Domain

The valid values than an attribute can take.

E

Edge

Diagram auto-layout term.The relationship connecting two entities.

Entity

A distinguishable person, place, thing, event or concept about which information is kept.

Entity Instance

A single occurrence or member of an entity.

Existence

The determination of whether a foreign key value inherited from a parent entity should always be required in the child entity. A relationship's existence can be either optional or mandatory.

F

Forward Engineering

The process of converting a logical model to a physical design for deployment on a database platform.

Foreign Key

A primary key or non-key attribute that is inherited from another entity.

Foreign Key Migration

The process of propagating foreign keys from parent entities to child entities based on relationship rules.

Function

SQL code that can be used to check the validity of data being entered in the database. A function accepts a number of parameters and passes back a single value to the calling program.

G

Glossary A list of terms in a special subject, field, or area of usage, with accompanying definitions.

H

I

Identifier

An attribute or column that helps to identify an entity or table instance; it is all or part of the entity's or table's primary key.

Identifying Relationship

A type of relationship in which the parent entity contributes its primary key as part of the child entity's primary key.

Independent Entity Key

A type of entity in which no foreign keys participate in its primary key.

Index

A database object used to enforce unique values in a table; an index can also be used to access table data more efficiently.

Inheritance

The process of propagating foreign keys from parent entities to child entities based on relationship rules.

Instance

A single occurrence or member of an entity.

Integrity

A property of a data model in which all assertions hold.

Integrity Constraint

A database feature that enforces foreign key relationships.

Inversion Entry

An attribute or set of attributes that do not uniquely identify every instance of an entity, but which are frequently used for access. The database implementation of an inversion entry is a non unique index.

Inverse Verb

A description of a relationship that conveys the business rule implied by the relationship. A verb phrase is read from the child entity to the parent entity like a sentence.

IRD Rules

A business rule governing the treatment of Inserts, Replacements and Deletions of entity instances.

J

K

Key

A key is one or more columns that can be used to identify or access a particular row or set of rows. Keys can be created in a table, index, or referential constraint. A column can be part of more than one key. See also Composite Key and Unique Key.

Key Area

The portion of the entity box that displays the primary key. This is the area above the line dividing the entity box.

Key-Based Model

A data model in third normal form or higher.

L

Library

A piece of BASIC code that can be reused in different macros.

Logical Design

The dimension of a data model that addresses real system requirements in the abstract, without consideration of data storage, performance or other physical implementation issues.

M

Macro

Code written in the Sax BASIC language that can be used to retrieve or write information about objects.

Materialized View

Materialized views are used to dynamically copy data between distributed databases. There are two types of materialized views:

  • Complex
  • Simple

Complex materialized views copy part of a master table or data from more than one master table. Simple materialized views directly copy a single table. You cannot directly update the underlying data contained in materialized views.

Metadata

All the information about a data warehouse that is not the actual stored data itself. Metadata describes the structure and relationship of data.

Metamodel

A model about models. A metamodel describes the underlying structure of a model.

Migration

The process by which a parent entity contributes foreign keys to a child entity.

Model

Representation of the logical or physical design of a database.

N

Node

Diagram auto-layout term. Refers to a box on the model representing an entity or a view.

Node Groups

A named subset of one or more database partitions.

Non-Identifying Relationship

A type of relationship in which the primary key of the parent entity is inherited by the child entity as non-key attributes.

Non-Key Attribute

An attribute that does not participate in an entity's primary key.

Non-Specific Relationship

A type of relationship that implies a many-to-many relationship between two entities. Because many-to-many relationships cannot be logically resolved, non-specific relationships are used for notational purposes and do not result in any foreign key migration.

Normalization

The process of removing inaccurate, inconsistent, redundant and/or overly complex assertions in a data model.

Not Null

The state of always having a value.

Null

The state of having no value.

O

Object Type

An abstract data type or object composed of a collection of similar types of data.

P

Package

Contains all the information needed to process SQL statements from a single source file.

Parent Entity

An entity that contributes a foreign key to another entity.

Physical Design

The translation of a data model for implementation on a database platform. The physical design shows how the data is stored in the database.

Primary Key

An attribute or set of attributes that have been chosen to uniquely identify every instance of an entity.

Primary Key Attribute

An attribute that participates in an entity's primary key.

Procedure

A reusable block of PL/SQL, stored in the database, that applications can call. Procedures streamline code development, debugging and maintenance by being reusable. Procedures enhance database security by letting you write procedures granting users execution privileges to tables rather than letting them access tables directly.

Propagation

The process by which a parent entity contributes foreign keys to a child entity.

Q

R

Recursive Relationship

A special type of non-identifying relationships in which both the parent and child entity are the same.

Referential Integrity

Database features that automatically ensure that each foreign key value has a matching primary key value.

Relationship

A connection between two entities that conveys some association or business rule. In the IDEF1X methodology, there are three basic types of relationships: identifying relationships, non-identifying relationships, and non-specific relationships.

Relational Model

A tabular data model in which data is represented in tables with records stored in rows and data elements expressed as table columns.

Repository

A central database that stores information about the elements and structure of a data model.

' Restrict

A process to ensure that the deletion or update of a parent entity instance will not occur unless there are no child entity instances depending on it.

Reverse-Engineering

The process of extracting the definition of database objects, usually from a database's system catalog.

Role Name

An alternate name for a foreign key attribute. Role names are used for clarification and should better describe the role of an attribute within the context of a particular entity.

Rollback Segment

Records and manages changes in an Oracle database to maintain read consistency and transaction integrity.

Rule

A database object that enforces a business rule by requiring data to fulfill a condition.

S

Scale

The scale of a numeric column or attribute refers to the maximum number of digits to the right of the decimal point.

Schema

The definition or structure of data or database objects.

Schema Definition (XSD)

The XSD specifies how to formally describe the elements in an XML document. It is an abstract representation of an object's characteristics and how the object relates to other objects. The XSD is used to verify that each element in an XML document conforms to the element rules described in the XSD.

Sequence

A programmable database object that generates a definable sequence of values. Once defined, a sequence can be made available to many users.

Set Null

A process wherein the existence of foreign key values in the parent entity's primary key is verified; if the values cannot be verified, the trigger sets the foreign key values to null in the child entity in order to allow data modification operations to proceed.

Status Bar

ER/Studio Data Architect provides statistics pertaining to your logical and physical model in the status bar at the bottom of the application. The table below describes the statistics available on the Status bar:

Data Model Mode

Statistic

Definition

Logical

Views

Total number of views in the current model or submodel

Entities

Total number of entities in the current model or submodel

Attributes

Total number of attributes in the current model or submodel

Relationships

Total number of relationships established in the current model or submodel

Physical

Tables

Total number of tables in the current model or submodel

Views

Total number of views in the current model or submodel

Columns

Total number of columns in the current model or submodel

Foreign Keys

Total number of foreign keys in the current model or submodel

Stogroup

A set of volumes on direct access storage devices (DASD). The volumes hold the data sets in which tables and indexes are actually stored.

Sub-Graph

A group of interconnected entities and views on the model. ER/Studio Data Architect determines the cluster components and attempts to organize each internally as well as the positions of separate clusters in relation to each other.

Submodel

An independent view of all or part of a logical or physical model.

Subtype

A subset of entity instances that share common attributes or relationships distinct from other subsets.

Subtype Cluster

A hierarchical grouping of entities that share common characteristics, but which can be divided into separate entities with distinct entity instances. Also known as a category entity.

Supertype

The parent entity in a subtype cluster that represents the superset of the subtypes.

Surrogate Key

An attribute or set of attributes that is generated strictly to serve as an entity's primary key. The data in a surrogate key has no inherent meaning or purpose except to uniquely identify every instance of the entity.

Synonym

An alternate name for a database object.

T

Table

The basic unit of data storage in a database. Tables correspond to entities in the logical model.

Tablespace

A specialized storage structure used to hold one or more tables.

Text Block

Useful information about a diagram.

Title Block

General information about a diagram in a text field.

Toolbars

ER/Studio Data Architect toolbars are context-sensitive and change to reflect the element of the application you are using. Toolbar buttons offer quick access to common features of ER/Studio Data Architect. All functionality accessible from toolbar buttons are also accessible from Menus and Shortcut Menus. Toolbars change depending on if you are working with logical or physical models. You can move toolbars to anywhere on the ER/Studio Data Architect workspace. You can dock toolbars to the perimeters of the workspace and specify which toolbars you want displayed on the workspace.

Trigger

A special type of stored procedure that automatically executes when data modification operations such as INSERT, UPDATE, and DELETE occur.

U

Unification

Unification is the act of combining columns with the same name to create one single column. It normally occurs when you propagate a foreign key into a table that has an existing column of the same name.

Unique Index

A database access object that ensures that every row in a table can be uniquely identified.

Unique Key

A unique key is a key that is constrained so that no two of its values are equal. The columns of a unique key cannot contain null values. The constraint is enforced by the database manager during the execution of any operation that changes data values, such as INSERT or UPDATE. The mechanism used to enforce the constraint is called a unique index. Thus, every unique key is a key of a unique index.

User-Defined Datatype

A customized and reusable datatype built from basic datatypes.

V

Verb Phrase

A description of a relationship that conveys the business rule implied by the relationship. A verb phrase is read as the verb in a sentence with the parent and child entities serving as the objects and subjects.

View

A relational object used for constructing virtual views of data without regard for where the data resides.

View Relationship

A special type of relationship used to propagate attributes from an entity or a view to a view.

W

X

Y

== Z ==
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