Concurrent access

Question 1

ONE ISSUE - What is record lacking?

Answer 1

Record locking – with this technique, a record is locked when it is being accessed by a user with write access; this prevents additional users from editing and saving the record until the original user has completed their database transaction.

Question 2

ONE ISSUE - What is serialisation?

Answer 2

this technique only permits one transaction at a time to take place when multiple users are updating a database.

Question 3

ONE ISSUE - What is Timestamp ordering?

Answer 3

this approach timestamps the start time of each database transaction that takes place based on system clock. The oldest timestamp transaction takes priority and is executed first where multiple transactions take place on the same record.

Question 4

ONE ISSUE - What is Commitment ordering?

Answer 4

in this case, the order of operation of concurrent transactions is based on the timestamp and the precedence of the particular command requested; for example, some commands take precedence and have priority, so they are, therefore, executed before older timestamp transactions