Databases

Question 1

Data Normalisation

Answer 1

A staged mathematical process which removes repeated groups of data and inconsistencies

Question 2

Distributed database

Answer 2

Data stored on a number of computers at different locations but appears as one logical database

Question 3

Data warehouse

Answer 3

A large collection of archived data used for decision making

Question 4

Data mining

Answer 4

Interrogating data to find patterns in the data which is stored in the database

Question 5

Security of relational databases

Answer 5

• Hierarchy of passwords (Passwords to see separate parts of the database)
• Data stored separately from programs
• Access rights to parts of the program

Question 6

Advantages of distributed databases

Answer 6

• Data lost on central site can be reduplicated from local site
• Allows sharing of data and the results of processing
• New locations can be added without rewriting database
• Faster responses for user queries
• Easier backup and copying
• One server fails, other server can be used

Question 7

Disadvantages of distributed databases

Answer 7

• Software more complex than a centralised database
• Data transfers present security risk from hackers
• Data inconsistencies from data stored and updated in more than one location
• Heavy reliance on networks which are not always reliable
• Server link failed data not accessible