Q7. What is recoverable and nonrecoverable schedule? Explain with example.
Recoverable Schedule:
A schedule is recoverable if a transaction commits only after all the transactions from which it has
read have committed.
Example:
T1: r1(X) w1(X) Commit
T2: r2(X) Commit
Here, T2 reads X written by T1, and T1 commits before T2, so it's recoverable.
Non-Recoverable Schedule:
If a transaction commits before the transaction it has read from commits, the schedule is
non-recoverable.
Example:
T1: r1(X) w1(X)
T2: r2(X) Commit
Abort
If T1 aborts after T2 commits, then T2 has read dirty data, hence it's non-recoverable.
Deadlock and Two Approaches to Deadlock Prevention:
Deadlock: Occurs when two or more transactions wait indefinitely for each other to release locks.
Approaches:
