Chapter 19, Problem 10PE

Explanation of Solution

Dealing with the difficulty:

Recovery schemes are normally used for detecting failures and restoring the database to a consistent state.

It is more difficult to recover from interactive transactions than batch transactions because of the following reasons:

• Some actions in interactive transactions cannot be recovered.
• For example, consider a write statement used by an ATM machine to dispense money to a customer.
  • One way to deal with such statements are by writing all the statements at the end of the transaction.
  • Hence, no harm will be done even if the transaction aborts anywhere from the beginning to the end...