Database Integrity

Suppose that you share a checking account with someone else, and you both attempt to withdraw $100 simultaneously from different ATMs. Perhaps you like to bid in online auctions, where many near-simultaneous bids often come in during the last few seconds. Similar kinds of conflicts can arise anywhere that multiple users may want simultaneous access to a limited resource.

Select one such situation and explain which strategy (optimistic or pessimistic) the organization should use to resolve the conflict. Consider the likelihood of simultaneous, conflicting transactions, the effect on the user when a conflict is resolved, and whether multiple database or Web servers are involved. Also look at the efficiency, reliability, and complexity of the solution. What other factors could be important? Explain your reasoning.