Data Administrator (DA)
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Data Administrator (DA)
The need for a data administrator arises in a very large organization where many databases may exist. The data administrator is responsible for the whole information resource. He develops the requirements for databases, develops logical design and other non-technical functions. He also controls and manages the database, establishes data standards, communicates with users, prepares logical design, develops data dictionary, plans the development of database and application programs train users and maintain documentation.
Data Dictionary
The data dictionary is a repository of information that describes the logical structure of the database. It contains record types, data item types, and data aggregates, etc. Data dictionaries in some systems store database schema and can be used to create and process databases. The data dictionary contains metadata. Metadata is the data about the data stored in the database.
Uses of Data Dictionary
Different uses of the data dictionaries are as follows: Information about Data: It is used to collect and store information about data in a central location. It helps the management to get control over data as a resource. Communication with Users: It provides great help in communication as it stores the exact meanings of data items. An exact definition of each item should be stored in a data dictionary that can be used in case of any problem. Record of Change in Database Structure: It keeps track of changes to the database structure. The changes such as the creation of new data items or modification of data item descriptions should be recorded in the data dictionary. Determining the Impact of Change: Data dictionary records each item and its relationships. DBA can see the effects of a change. Recording Access Control Information: Data dictionary stores all information about different authorized users. It also contains the types of access for all users. Audit Information: It can also keep a record of each access to the database. This information can later be used for audit purposes.
Types of Data Dictionaries
Different types of data dictionaries are as follows:
1. Integrated Data Dictionary
A data dictionary that is part of DBMS is called an integrated data dictionary. It performs many functions throughout the life of the database not only in the design phase. There are two types of integrated data dictionaries: Active Data Dictionary: The integrated data dictionary is called active if it is checked by DBMS every time a database is accessed. It is always consistent with the actual database structure. It is automatically maintained by the system.
Passive Data Dictionary: The integrated data dictionary is called passive if it is not used in day-to-day database processing.
2. Freestanding Data Dictionary
A data dictionary that is available without a particular DBMS is called a freestanding data dictionary. It can be a commercial product or a simple file developed by the designer. Many CASE packages provide a data dictionary tool. It is preferable in the initial design stages before choosing any particular DBMS.
