Consider a database with objects x and y and assume that there are two transactions t1 and t2. transaction t1 reads objects x and y and then writes object x. transaction t2 reads objects x and y and then writes objects x and y. give three example histories over transactions t1 and t2 that result in :

a)a write-read conflict

b)a read-write conflict

c)a write-write conflict

show that each serial history involving transactions t1 and t2 preserves the consistency requirement of the database.

specify a recovery strategy which would never require undoing or re-doing side-effects (both undoing and redoing are not required).

how would such a recovery strategy be implemented?