DBMS Short Question And Answer Set-6

1. What is the use of RAID?
A variety of disk-organization techniques, collectively called redundant arrays of independent disks are used to improve the performance and reliability.

2. Explain how reliability can be improved through redundancy?
The simplest approach to introducing redundancy is to duplicate every disk. This technique is called mirroring or shadowing. A logical disk then consists of two physical disks, and write is carried out on both the disk. If one of the disks fails the data can be read from the other. Data will be lost if the second disk fails before the first fail ed disk is repaired.

3. What is called mirroring?
The simplest approach to introducing redundancy is to duplicate every disk. This technique is called mirroring or shadowing.

4. What is meant by Multi-dimensional database?
A multi-dimensional database is a computer software system designed to allow for efficient and convenient storage and retrieval of large volumes of data that is (1) intimately related and (2) stored, viewed and analyzed from different perspectives and these perspectives are called dimensions.

5. What is meant by Spatial database?
A spatial database is a database that is optimized to store query data that represents objects defined in geometric space. Most spatial databases allow representing simple geometric objects such as points, lines and polygons. Some spatial databases handle more complex structures such as 3D objects, topological coverages,etc.

6. What is meant by Mobile database?
A mobile database is a database that resides on mobile device such as a PDA, a smart phone, or a laptop. Such devices are often limited in resources such as memory, computing power and battery power.

7. List the threats to databases.

  •  Loss of integrity
  •  Loss of availability
  •  Loss of confidentiality

8. List out the control measures.

  • Access control
  • Inference control
  • Flow control
  • Data encryption

9. What is meant by Data warehouse?
A data warehouse is a repository (archive) of information gathered from multiple sources, stored under a unified schema at a single site.

  • Greatly simplifies querying, permits study of historical trends
  • Shifts decision support query load away from transaction processing systems

10. Define Data mining.
Data mining – knowledge discovery in database. Data mining is the process of semiautomatically analyzing large databases to find useful patterns.

11. List out the operations done in data warehouse.

  • Roll up
  • Drill down
  • Pivot
  • Sorting
  • Selection

12. List out the functionalities of Data warehouse.

  • Data cleaning
  • Data transformation
  • Data integration
  • Data loading &
  • Periodic data refreshing

13. List the types of security mechanisms.

  • Discretionary security mechanisms
  • Mandatory security mechanisms

14. What are the database design issues?

  • Legal and ethical issues
  • Policy issues
  • System related issues

15. What are the actions performed by DBA?

  • Account creation
  • Privilege granting
  • Privilege revocation
  • Security level assignment

16. What are the steps for designing a warehouse?

  •  Choose a business process to model
  •  Choose the grain of the business process
  •  Choose the dimensions that will apply to each fact table record
  •  Choose the measures that will populate each fact table record

17. What are the issues in data warehouse design?

  • When and how to gather data
  • What schema to use
  • Data cleansing
  • How to propagate updates
  • What data to summarize

18. What are the goals of data mining?

  • Prediction
  • Identification
  • Classification
  • Optimization