CRUD , ACID , Transaction processing...ect

Question 1

Transaction processing

Answer 1

Operations that are individual and indivisible.
- each transaction must either succeed or fail as a complete unit
- change the contents of the database

Question 2

CRUD

Answer 2

• Create
• Read
• Update
• Delete

This is the minimum functionality required for a transactional database

Question 3

Committing

Answer 3

Only making changes to a database when all external aspects of a transaction are complete

Question 4

ACID

Answer 4

• Atomicity
• Consistency
• Isolation
• Durability

Question 5

Atomicity

Answer 5

Transactions either fail or succeed , never partially succeed.

• A change in the database must be completed or not at all

Question 6

Consistency

Answer 6

Transaction must only change the database according to the rules of the database (database must go from one consistent state to another)

Question 7

Isolation

Answer 7

A transaction must not overwrite or affect another.
- e.g. a ticket is locked so others can not purchase
- this is until purhcase is complete or timed out

Question 8

Durability

Answer 8

Once a transaction is started its data is protected until it is completed or fails
- changed made by a transaction must persist

Question 9

Deadlock

Answer 9

2 users are attempting to make changes to the same record at the same time. this will make it impossible to submit one consistant form of the record

• locking the record to one user at a time resolves this problem
• part of isolation in ACID
• machine learning is generally used for this

Question 10

Data mining

Answer 10

Analysis of large sets of data to identify patterns and relationships (generally for commercial use)
- supermarkets
- amazon (reccomend items)
- medicine (predict problems)