TeradataMeta Data Services (MDS) provides a means of storing, administering, and navigating metadata in Teradata. It is the only metadata management system optimized for and integrated with Teradata Database environment.
About Metadata
Metadata is the term applied to the definitions of the data stored in Teradata Database. Simply put, metadata is data about data. In a transaction processing database environment, a Data Dictionary generally satisfies the need for data about data. In the data warehouse
environment, the requirements for a more elaborate metadata storage system can exceed the capabilities of the Data Dictionary.
Metadata plays an important role across Teradata Database architecture. In the operational database environment, that role is very formal. All development should use metadata as a standard part of the design and development process. As far as the data warehouse is
concerned, metadata is used to locate data. Without it, you cannot not interact with the data in the data warehouse because you have no means of knowing how the tables are structured, what the precise definitions of the data are, or where the data originated.
Types of Metadata
Metadata has been around for as long as there have been programs and data. However, in the world of data warehouses, metadata takes on a new level of importance. Using metadata, you can make the most effective use of Teradata. Metadata allows the decision support system (DSS) analyst to navigate through the possibilities.
The major component of the DSS environment is archival data, that is, data with a timestamp. Because archival data is timestamped, it makes sense to store metadata with the actual occurrences of data, which are time stamped as well.
Teradata Meta Data Services
Teradata Meta Data Services
Teradata MDS is software that creates a repository in a Teradata Database in which metadata is stored. Teradata MDS also permits the DSS analyst to administer and navigate metadata in the warehouse. The following table describes the benefits of Teradata MDS to several user groups.
For the… The following types of metadata are stored…
data model • Description
• Specification
• The layout of the physical data model tables
• Relation between the data model and the data warehouse
data warehouse • Data source (system of record)
• Definition of the system of record
• Mapping from system of record to the data warehouse and other places defined in the environment
• Table structures and attributes
• Any relationship or artifacts of relationships
• Transformation of data as it passes into the data warehouse
• History of extracts
• Extract logging
• Common routines for data access
columns • Columns in a row
• Order in which the columns appear
• Physical structure of the columns
• Any variable-length columns
• Any columns with NULL values
• Unit of measure of any numeric columns
• Any encoding used
database design • Description of the layouts used
• Structure of data as known to the programmers and analysts
Chapter 19: Teradata Meta Data Services Teradata Meta Data Services
Creating Teradata Meta Data Repository
Teradata MDS repository is a set of tables, views, and macros stored in a Teradata Database. You must use MDS program software to create these tables before metadata can be added, stored, or accessed.
Connecting to Teradata Meta Data Repository
Each system running a Teradata MDS application must have the following:
• The appropriate Teradata ODBC driver (see ODBC Driver for Teradata User Guide for more information).
For this type of user… Teradata MDS…
application developers • Provides a persistent store for application metadata so that developers can concentrate on developing application functions.
• Allows the developer to manipulate metadata with the same techniques used to manipulate other data.
• Provides security (MDS controls the read and write access).
• Allows metadata to be shared between applications. This allows integration of tools such as ordered analytical functions and data mining tools.
• Allows application data to be modeled around Teradata Database metadata maintained by MDS. MDS maintains the metadata so that the application is kept current with database changes.
database administrator • Provides a common repository for Teradata components.
• Provides a single shared copy of metadata, or a single version of the business. One copy eliminates multiple islands of redundant metadata that can cause confusion and administrative
difficulties.
• Provides the capabilities to browse through data in the repository and to drill-down to see successive levels of detail.
• Shows interrelationships between different data definitions.
• Provides impact analysis of proposed changes.
business user • Provides the foundation for a “warehouse view” of enterprise computing.
• Allows business analysts to quickly determine where their data comes from, how it was changed, when it was last updated, and how the answer was determined. This greatly increases the value of the detail data and implicitly the value of the metadata.
• Supports third-party tools that can be used to import metadata into MDS for viewing.
• Supports a web browser that provides general reporting and search capabilities and shows strategic metadata relationships.
For More Information
For More Information
For more information on the topics presented in this chapter, see the following Teradata Meta Data Services and Teradata Tools and Utilities books.
IF you want to learn more about… See…
Metadata • Teradata Meta Data Services Administrator
Guide
• Teradata Meta Data Services Programmer Guide
Types of Metadata Teradata MDS