4.11 Database Mgt

Question 1

DBMS Objectives

Answer 1

1) Integrity - the state of the database is the same after a transaction has occurred as it was prior to the transaction
2) Performance - efficient processing and reporting
3) Availability - in the event of failure, the data should be available in its original state
4) Access control - ensuring data is available only to authorised users and objects
5) Privacy - constraining data disclosure

Question 2

Two type os issues impacting integrity.

Answer 2

Concurrency

Transactional

Question 3

What are concurrency issues impacting integrity?

Answer 3

These issues arise when a database is simultaneously accessed by subjects and other objects

Question 4

What rules/controls help with the concurrency issues?

Answer 4

Semantic integrity - structural and semantic rules are enforced including deadlocking

Referential integrity - ensures that relationships between tables remain consistent (synchronised)

Commit Operation - protects the transaction

Question 5

What acronym/characteristics help to guarantee reliability and integrity of transactional data?

Answer 5

A - Atomicity - transactions must be implemented in their entirety, or they must be completely rolled back

C - Consistency - transactions must be correct across all instances

I - Isolation - Transactions must not interact with other transactions until completed

D - Durability - Transactions cannot be rolled back, once committed

Question 6

What is the difference between semantic data integrity and structural database integrity?

Answer 6

Semantic - consistency of the data itself - deals with the DBMS features and processes that can be used to ensure accuracy and viability of the data contents of a database.

Structural database integrity - consistency of the “holders” of the data (database objects).