Data Administrator (DA) and Database Administrator (DBA)
database administrators
database administrators

Both of these terms – Data administrator and Database administrator – seem to be similar. Though they both are responsible for managing database for an organization they both are different from each other in their required skills and responsibilities.
The following sub-sections explore these concepts of data administrator and database administrator.

Data administrator (DA)

“The data administrator may be a person within the organization who controls the info of the database.”

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DA determines what data to be stored in database supported requirements of the organization.
DA is involved more within the requirements gathering, analysis, and style phases.
DA may be a manager or some senior level person in a corporation who understands organizational requirements with reference to data.
DA doesn't got to be a technical person, but any quite knowledge about database technology are often more beneficiary.
In short, DA is a business focused person, but, he/she should understand more about the database technology.

Database administrator (DBA)        
“The database administrator may be a person within the organization who controls the planning and therefore the use of the database.”

DBA provides necessary technical support for implementing a database.
DBA is involved more within the design, development, testing and operational phases.
DBA may be a technical person having knowledge of database technology.
DBA doesn't got to be a business person, but any quite knowledge about an functionality of a corporation are often more beneficiary.
In short, DBA is a technically focused person, but, he/she should understand more about the business to administer the databases effectively.

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Functions and Responsibilities of DBAs.

1.        Schema definition :
The DBA defines the logical schema of the database. A schema refers to the general logical structure of the database.
According to this schema database are going to be developed to store required data for a corporation .

2.       Storage structure and access method definition :
The DBA decides how the info is to be represented within the stored database.
Based on this, storage structure of the database and access methods of knowledge is defined.

3.       Assisting application programmers :
The DBA provides assistance to application programmers to develop application programs.
database administrators
database administrators
4.       Physical organization modification :
The DBA modifies the physical organization of the database to reflect the changing needs of the organization or to enhance performance.

5.       Approving data access :
The DBA determines which user needs access to which a part of the database.
According to this, various sorts of authorizations are granted to different users. this is often required to stop unauthorized access of a database.

6.       Monitoring performance :
The DBA monitors performance of the system. The DBA ensures that better performance is maintained by making changes in physical or logical schema if required.

7.       Backup and Recovery
Database may be a valuable asset for any organization. It shouldn't be lost or damaged.
The DBA ensures this by periodically backing up the database on magnetic tapes or remote servers. just in case of failures, like flood or virus attack, database is recovered from this backup

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Data warehouse

Data stored in databases can be one of the two types: first, operational data, which is used in day-to-day operations; and second, decision making data, which is used occasionally to make decisions.

“A data warehouse may be a decision support database that's maintained separately from the organization’s operational database.”

Data stored in data warehouse possess following characteristics:
1.       Subject-oriented
2.       Integrated
3.       Time-variant
4.       Non-volatile
These characteristics are described below:

Data warehouse is organized around the manor subjects or topics of an organization.
These subjects are those for which there may be a need to take some decision. For example, customers, products, sales etc.

Data to be stored in a data warehouse might be coming from different locations, such as from different branches of a company or bank.
It is also possible that this data may have different structures according to their source.
All such kind of data is integrated in data warehouse. This means, it is converted to some homogenous structure.

Data warehouse provides information from a historical perspective.
Data stored in data warehouse contains time element to reflect timing of the data.
So, data in data warehouse indicates what happened previous day, last week, last month, during past two years and so on.

Data stored in data warehouse is never deleted or updated. New data is always added as a supplement to the database on a regular basis.

Data dictionary :
Data dictionary or data directory is a file that contains metadata.
Data dictionary is typically a neighborhood of the system catalog that's generated for every database.

Data dictionary stores and manages following types of information.
Description of the schema, i.e. overall logical structure, of the database. This can involve information such as table names, owners, column names, data types, size, and constraints.
Detailed information of physical database design, such as storage structures, access paths, and field & record size.

Description of the database users, their responsibilities & access rights.
Descriptions of the database transactions, i.e. operations performed on database.
Relationships between transaction and data items to determine which transaction are affected when certain data definitions are changed.
Relationships among entities, such as, which account belongs to which branch in a banking system.
Usage statistics, such as frequencies of queries & transactions.

Access counts to different parts of the database.
Components of data dictionaries
A data dictionary contains the following components:

1.       Entities
2.       Attributes
3.       Relationships
4.       Key
These components are described below:


“An entity is a ‘thing’ or ‘object’ existing in the real world that is distinguishable from all other objects.”

An entity represents an object in which user is interested. In other words, an entity represents any item about which information is stored.
For example, any particular customer, say ‘Riya’, or some particular account, say ‘A01’, can be considered as an entity.

An attribute may be a property or characteristic of an entity.
For example, customer id, name, address, contact numbers are attributes of entity customer. Similarly, account number, balance, branch name are attributes of entity account.

A relationship is an association or connection among entities.
For example, an association between some account, say ‘A01’, and branch, say ‘anand’ is referred as relationship.

A data item or a field, which is used to identify a record in a database, is referred as key.
A primary key's wont to uniquely identify a record. For example, customer id acts as a primary key for customers.
When more than one field is used to identify a record, it is called concatenated key. For example, customer id & name are concatenated key for customer.

Active and Passive Data Dictionaries:

Data dictionaries can be either active or passive as explained below:
Active data dictionary:
If data dictionary is managed automatically by database management software, it is called an active data dictionary.
It is also called integrated data dictionary.
It is always consistent with the current definition and structure of the database. Because, it is managed by database system itself.

Passive data dictionary:
If data dictionary is managed by the user of the system, it is called a passive data dictionary.
It is also called non-integrated data dictionary.
It may not be consistent with the current definition and structure of the database. Because, it requires explicit changes whenever structure of the database changes.

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