Exercise 17.8 Answer each of the following questions briefly. The questions are based on t...

Exercise 17.8 Answer each of the following questions briefly. The questions are based on the following relational schema:

Emp(eid: integer, ename: string, age: integer, salary: real, did: integer)
Dept(did: integer, dname: string, floor: integer)

and on the following update command:

Figure 17.3

replace (salary = 1.1 * EMP.salary) where EMP.ename = ‘Santa’

1. Give an example of a query that would conflict with this command (in a concurrency control sense) if both were run at the same time. Explain what could go wrong, and how locking tuples would solve the problem.
2. Give an example of a query or a command that would conflict with this command, such that the conflict could not be resolved by just locking individual tuples or pages but requires index locking.
3. Explain what index locking is and how it resolves the preceding conflict.