A
application information metamodel (AIM)
A metamodel that describes how a set of meta data is stored in the MDS repository.
application programming interface (API)
A set of routines used by an application program to direct the performance of procedures by the computer’s operating system.
attribute
A field represented by a column within an object (entity). An object may be a table, view or report.
abstract class
An abstract class is a class that can not have object instances. An abstract class can have properties and can be the source or destination class in relationships. Abstract classes are created to enable subclasses of the class to inherit the properties and relationships of the abstract class.
B
business definition
A definition that uses business terminology to describe a data object.
business rules
The logic applied to calculate or otherwise derive a value.
C
class
In object-oriented terminology, a class defines a type of object. The definition encapsulates both the data and the associated behaviors (executable code) that objects of the class can perform.
client load metamodel (CLM).
An MDS-defined metamodel for the Teradata client load utilities. The CLM stores meta data for loading data into the Teradata system through the use of the Teradata client load utilities.
client/server
A distributed technology approach where the processing is divided by function. The server performs shared functions — managing communications, providing database services, and so on. The client performs individual user functions — providing customized interfaces, performing screen to screen navigation, offering help functions, and so on.
collection
Relationships map or link one or more objects from one class to one or more objects in another class. The resulting mapping or linking is called a collection.
Class objects can be added to or removed from a collection. When a new version of an object is created, MDS automatically assigns the new version the same collection states as its previous version. Because the new version becomes the current version of the object, changes to collections of an object are only reflected in the new version. The previous versions' collections are frozen to retain historical information.
A user must be assigned the appropriate access rights on objects to remove them from or add them to collections. For example, to update an object, the user requires read access to the object. To delete an object, the user requires collection privileges to remove the object from existing collections. The types of access that can be assigned to a user or application group in a security profile. See published state, security profile, versioning.
current
In a repository with versioning on, the current version of an object is the most recently written version as created by WriteObject, which writes new versions of objects to the repository. See published state, inactive, dormant.
D
data
Items representing facts, text, graphics, bit-mapped images, sound, analog, or digital live-video segments. Data is the raw material of a system supplied by data producers and is used by information consumers to create information.
database information metamodel (DIM)
An application information metamodel (AIM) that defines how a Teradata schema will be stored in the MDS repository.
database schema
The logical and physical definition of a database structure.
data definition language (DDL).
A language that defines all attributes and properties of a database, especially record layouts, field definitions, key fields, file locations, and storage strategy.
data dictionary
A database about data and database structures. A catalog of all data elements, containing their names, structures, and information about their usage. A central location for meta data. Normally, data dictionaries are designed to store a limited set of available meta data, concentrating on the information relating to the data elements, databases, files and programs of implemented systems.
data element
The most elementary unit of data that can be identified and described in a dictionary or repository that cannot be subdivided.
data length
The physical length of the column or field that stores the data. Example: 50
data type
The physical types of data that are assigned by the database or file management system. Examples are Integer, Decimal, Date, Character, VarChar.
data warehouse
An implementation of an informational database used to store sharable data sourced from an operational database-of-record. It is typically a subject database that allows users to tap into a company's vast store of operational data to track and respond to business trends and facilitate forecasting and planning efforts.
derived class
A derived class is a base class and a set of derived properties. There are no physical objects in a derived class. Derived class objects are created by joining properties in a base class with properties in related classes. Derived class objects are read only. Derived classes are similar to a view in an RDBMS.
document type definition (DTD)
In XML, a DTD defines the grammar expected by the metaxml program necessary for importing data into the MDS repository. The XML parser ensures that an XML input document conforms to the grammar.
dormant
An object is dormant if it is not currently active in the repository when data versioning is supported by the object class. See current, inactive, published state, versioning.
E
entity
A database object such as a table or view.
extensible markup language (XML)
A condensed form of SGML that lets information developers and designers create customized tags, offering greater flexibility in organizing and presenting information than is possible with the older HTML document coding system.
I
inactive
An object is inactive or dormant if it is not currently active in the repository when data versioning is supported by the object class. See current, dormant, published state, versioning.
inheritance
Inheritance is a feature that allows creation of a class that inherits the properties and relationships from a previously defined class. A class that inherits from another class is called a subclass. The class that the subclass "inherits from" is called the superclass.
interface
An interface is a set of function definitions. An interface can inherit from any base interface.
Internet Information Services (IIS)
MDS software (MetaSurf) must be installed on the IIS Web server if MDS users will be using their web browser to access the MDS repository.
L
label
Part of versioning, labels are used to identify objects by assigning each a name, description, creator name, object GUID, owner, security profile name, and security profile reference. Only the name parameter is required. When unspecified, the owner defaults to the MDS user running the script assigning the label. A default GUID is supplied by the MDS engine. A default security profile is provided by MDSDefaultSecurityProfile.
M
metadata or meta data
Meta data is information about data. Examples of meta data include data element descriptions, data type descriptions, attribute/property descriptions, range/domain descriptions, and process/method descriptions. Meta data includes things like the name, length, valid values, business definitions, and description of a data element. Meta data is stored in a repository. It insulates the data warehouse from changes in the schema of operational systems.
Meta Data Services (MDS)
The Teradata Meta Data Services product provides a means of storing, administering, and navigating meta data in a Teradata data warehouse. It is the only meta data management system optimized for and integrated with the Teradata environment.
MDS repository
A set of tables that resides in the Teradata Database Systems.
N
null
A null value tells you the value for that row is either missing, unknown, not yet known or inapplicable. Placing a zero in the row would not reflect the accurate state of the row, because zero is a value. This way you can search for "missing" data and SQL supports the notion of null values.
O
object
A person, place, thing, or concept that has characteristics of interest to an environment. In terms of an object-oriented system, an object is an entity that combines descriptions of data and behavior.
object description
All the properties and associations that describe a particular object.
open database connectivity (ODBC)
A call-level interface that allows applications to access data in any database for which there is an ODBC driver.
P
propagation delete
Enables delete propagation for objects in the collections of the specified relationship description.
published state
In a repository with versioning on, the published state is the state of the most recently written version of an object. The state is created by WriteObject, which writes a new version of an object to the repository. The new object has the same GUID as the current version, but the LOID is different, and the version number is one greater than the current version of the object. The write produces the new current or published version of the object, replacing the previously current version, which goes into the inactive published state. The highest numbered version of an object always has the published state of current. All other versions are considered non-current or inactive. The state is a read-only property that cannot be set by an application.
Q
query
A (usually) complex SELECT statement for decision support.
R
RDBMS
Relational database management system.
redundancy
The storage of multiple copies of identical data.
Relay Services Gateway (RSG)
The RSG is a Teradata VPROC which relays messages between Teradata and the MDS DDL Gateway.
repository
A database system used to store information. In data warehousing repositories are most commonly used to store meta data.
S
schema
The logical and physical definition of data elements, physical characteristics and inter-relationships.
security profile
A named object containing the permissions for a set of groups and users that is assigned to each object in the repository. Access to the object is based on permissions defined in the assigned profile. The profile ID is stored in a common property of each object.
server
A service that provides standard functions for clients in response to standard messages from clients. A commonly used definition of server also refers to the physical computer from which services are provided.
structured query language (SQL)
A database sublanguage used in querying, updating, and managing relational databases — the de facto standard for database products.
subclass
A subclass is a class that inherits the properties and relationships from a previously defined class. The class that the subclass "inherits from" is called the superclass. A subclass can inherit from up to five superclasses.
superclass
tA superclass is a defined class that a subclass inherits the properties and relationships from.
T
TCP/IP (Transmission Control Protocol/Internet Protocol)
A protocol developed by the Department of Defense for communications between computers. It is built into the Linux system and has become the de facto standard for data transmission over networks, including the Internet.
V
valid values
A list, definition, or example of the values that can be entered in a data element (column/field/term). Examples of allowable values are: specifying the type of data - like “amounts”; listing ranges of values; domain tables/lists.
versioning
When an object is initially created, it is assigned version number 1. When a class supports data versioning, and an application calls WriteObject() for an object in the class, MDS creates a new version of the object and assigns it a version number incremented by 1. If versioning is not supported by a class, WriteObject overwrites the current object. The new version retains the unique property values of the previous version, except for those specifically set in the CMetaObject object.