RDBMS Unit-IPartII

Unit-I		Unit-II	Unit-III	Unit-IV	Unit-V
Part-I	Part-II	Part-I	Part-I	Part-I	Total
Part-III	Part-IV	Part-II	Part-II	Part-II
Part-V		Part-III

 5. Explain File System Vs Dbms?

LOGICAL DBMS ARCHITECTURE

6.     Explain  In Detail 3 –Level ANSI-SPARC Architecture?

Ans:

The American National Standards Institute (ANSI) Standards Planning and Requirements Committee (SPARC), or ANSI/X3/SPARC, produced Three-Level architecture in 1975 .It is known as ANSI-SPARC ARCHITECTURE.

The ANSI-SPARC database architecture uses three levels of abstraction: external, conceptual, and internal.

The objective of the three-level architecture is to separate each user’s view of the database from the way the database is physically represented.

 Reasons why this separation :

• Each user should be able to access the same data, but have a different customized view of the data.

• Users should not have to deal directly with physical database storage details, such as indexing or hashing .

 • The DBA should be able to change the database storage structures without affecting the users’ views.

• The internal structure of the database should be unaffected by changes to the physical aspects of storage, such as  changing to a new storage device.

External Level

The external level consists of a number of different external views(users views) of the database. This level describes that part of the database that is relevant to each user.

Different views may have different representations of the same data. For example, one user may view dates in the form (day, month, year), while another may view dates as (year, month, day). 

Conceptual Level

The conceptual level is the community view of the database. This is middle level in the three-level architecture is the conceptual level. This level describes what data is stored in the database and the relationships among the data. 

The conceptual level represents:

• all entities, their attributes, and their relationships;

• the constraints on the data;

• semantic information about the data;

• security and integrity information.

Internal Level

The internal level is the computer’s view of the database .This level describes how the data is stored in the database .

The internal level covers the physical implementation of the database .

The internal level is concerned with such things as:

• Storage space allocation for data and indexes;

• Record descriptions for storage

• Record placement;

• Data compression and data encryption techniques.

Database Administrator (DBA) Functions & Role

7.     What are the role and functions of DBA?

Ans:

The DBA is also responsible for defining procedures to recover the database from failures due to human, natural, or hardware causes with minimal loss of data. This recovery procedure should enable the organisation to continue to function and the intact portion of the database should continue to be available.

Thus, the functions of DBA are:

1.     Defining the Schema 

The DBA defines the schema which contains the structure of the data in the application. The DBA determines what data needs to be present in the system ad how this data has to be represented and organized. As per this construction, database will be produced to store required information for an association.

2.     Defining Storage Structure and Access Method:

The DBA chooses how the information is to be put away in database.

3.     Interacting with Users 

The DBA needs to interact continuously with the users to understand the data in the system and its use. The DBA figures out which client needs access to which part of the database

4.     Defining Security & Integrity Checks 

The DBA finds about the access restrictions to be defined and defines security checks accordingly. Data Integrity checks are also defined by the DBA.

5.    Defining Backup / Recovery Procedures 

The DBA also defines procedures for backup and recovery. Defining backup procedures includes specifying what data is to backed up, the periodicity of taking backups and also the medium and storage place for the backup data. 

6.     Monitoring Performance 

The DBA has to continuously monitor the performance of the queries and take measures to optimize all the queries in the application. 

7.     Assistance to Application Programmers:

The DBA gives help to application software engineers to create application programs.

8.     Granting of authorisation for data access:

DBA allows the granting of different types of authorisation for data access to the various users of the database. 

The roles of DBA will be as follows

 

The DBA’s Managerial Role

 

1.End-User Support

The DBA interacts with the end user by providing data and information support services to the organization’s departments.

 

Gathering user requirements.

The DBA must work within the end-user community to help gather the data required to identify and describe the end-users’ problems. 

Building end-user confidence.

Finding adequate solutions to end-users’ problems increases end-user trust and confidence in the DBA function.

 

Resolving conflicts and problems.

Finding solutions to end-users’ problems in one department might trigger conflicts with other departments. The DBA has the authority and responsibility to resolve them.

Finding solutions to information needs. 

The DBA’s primary objective is to provide solutions to address the end-users’ information needs. The solutions are likely to require the development and management of Web servers to interface with the databases.

 

Ensuring quality and integrity of data and applications.

The DBA must work with both application programmers and end users to teach them the database standards and procedures required for data quality, access, and manipulation.

Managing the training and support of DBMS users.

The DBA must ensure that all users accessing the database have a basic understanding of the functions and use of the DBMS software. 

2.Policies, Procedures, and Standards

Policies are general statements of direction or action that communicate and support DBA goals.

Standards describe the minimum requirements of a given DBA activity; they are more detailed and specific than policies.

Procedures are written instructions that describe a series of steps to be followed during the performance of a given activity.

 3.Data Security, Privacy, and Integrity

The DBA use the security and integrity mechanisms provided by the DBMS to enforce the database administration policies. In addition, DBAs must team up with Internet security experts to build security mechanisms to safeguard data from possible attacks or unauthorized access.

4.Data Backup and Recovery

The DBA must also ensure that the data in the database can be fully recovered in case of physical data loss or loss of database integrity.

The management of database security, integrity, backup, and recovery is so critical that many DBA departments have created a position called the database security officer (DSO). The DSO’s sole job is to ensure database security and integrity. In large organizations, the DSO’s activities as follows 

1.     Periodic data and applications backups

2.     Proper backup identification.

3.     Convenient and safe backup storage.

4.     Physical protection of both hardware and software.

5.     Personal access control to the software of a database installation.

6.     Insurance coverage for the data in the database.

5. Data Distribution and Use

The DBA is responsible for ensuring that the data are distributed to the right people, at the right time, and in the right format. The DBA has to educate end users to produce the required information without being dependent on applications programmers. Naturally, the DBA must ensure that all users adhere to appropriate standards and procedures.

The DBA’s Technical Role

The DBA’s technical activities include the selection, installation, operation, maintenance, and upgrading of the DBMS and utility software, as well as the design, development, implementation, and maintenance of the application programs that interact with the database.

The technical aspects of the DBA’s job are rooted in the following areas of operation:

1.     Evaluating, selecting, and installing the DBMS and related utilities.

2.     Designing and implementing databases and applications.

3.     Testing and evaluating databases and applications.

4.     Operating the DBMS, utilities, and applications.

5.     Training and supporting users.

6.     Maintaining the DBMS, utilities, and applications