Consider the database system of a bank that employs snapshot isolation. Describe a nonserializable execution that would pose a challenge for the bank

Design a relational database schema from the Car Sharing IS domain class diagram. Output should look like image number 2

Sometimes a transaction has to be undone after it has committed because it was erroneously executed—for example, because of erroneous input by a bank teller. a. Give an example to show that using the normal transaction undo mechanism to undo such a transaction could lead to an inconsistent state. b. One way to handle this situation is to bring the whole database to a state prior to the commit of the erroneous transaction (called point-in-time recovery). Transactions that committed later have their effects rolled back with this scheme. Suggest a modification to the recovery algorithm of Section 19.4 to implement point-in-time recovery using database dumps. c. Later nonerroneous transactions can be reexecuted logically, if the updates are available in the form of SQL but cannot be reexecuted using their log records. Why?

Let's look at an airline database to see how snapshot isolation is used in practice. The airline, for instance, could agree to a nonserializable execution if it means better long-term outcomes.