Recoverability MCQs For Gate Exam

Recoverability MCQs — Q1–Q100

Q1

Schedule: r1(A) w2(A) c2 r1(B) c1
Which of the following is true?
A. Schedule is recoverable
B. Schedule is non-recoverable
C. Schedule is cascadeless
D. Schedule is strict

✅ Answer: A
Solution:

• T1 reads A before T2 writes A → no read-from uncommitted data.
• T2 commits before T1 commits, but T1 did not read T2’s write.
• Therefore, T1 can safely commit → schedule is recoverable.

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Q2

Schedule: r1(A) w2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T1 reads A, then T2 writes A.
• T1 commits before T2 commits → T1 read a value that could be overwritten by T2.
• If T2 aborts, T1 has already committed → violates recoverability.
• Schedule is non-recoverable.

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Q3

Schedule: w1(A) r2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads A after T1 wrote it.
• T1 commits before T2 → read-from committed data.
• No cascading aborts possible → recoverable schedule.

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Q4

Schedule: w1(A) r2(A) abort1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 read uncommitted value from T1.
• T1 aborts → T2 read invalid data.
• T2’s commit is not recoverable → schedule is non-recoverable.

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Q5

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads after T2 wrote A, but T2 commits before T3.
• T1 reads initial A → no read-from uncommitted values.
• All commits respect dependencies → recoverable.

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Q6

Schedule: r1(A) w2(A) c2 r1(B) c1
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads A before T2 writes → safe.
• T2 commits → T1 reads only committed data or its own read → recoverable.

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Q7

Schedule: w1(A) r2(A) w2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads A written by uncommitted T1 → dependency exists.
• T2 commits after T1 → violates recoverability if T1 aborts.
• Hence, non-recoverable.

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Q8

Schedule: w1(A) r2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads committed value from T1.
• T1 committed before T2 → safe → recoverable schedule.

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Q9

Schedule: r1(A) w2(A) r3(A) w2(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads A before T2 commits, but T2 commits before T3 → read-from committed data.
• No cascading aborts required → recoverable.

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Q10

Schedule: r1(A) w2(A) r3(A) c2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T3 reads A before T2 commits → read-from uncommitted.
• T2 commits after T3 → violates recoverability.
• Hence, non-recoverable.

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Q11

Schedule: w1(A) r2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• Both T2 and T3 read A after T1 wrote and committed → no read-from uncommitted data.
• Recoverable schedule.

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Q12

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T3 reads from T2 → T2 aborts → T3 read invalid data.
• T3 already committed or about to → violates recoverability → non-recoverable.

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Q13

Schedule: r1(A) r2(A) w2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial A → no dependency.
• T2 writes and commits → safe → recoverable.

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Q14

Schedule: w1(A) r2(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted value from T1 → dependency.
• If T1 aborts, T2 must abort → T3 read T2’s value → chain of dependencies.
• Violates recoverability → non-recoverable.

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Q15

Schedule: r1(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial value → safe.
• T2 writes and commits → T3 writes after T2 → all read-from committed values → recoverable.

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Q16

Schedule: r1(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads A after T2 committed → safe.
• T1 read before T2 wrote → safe.
• All dependencies respected → recoverable.

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Q17

Schedule: w1(A) r2(A) r3(A) w2(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 and T3 read committed A from T1 → safe.
• Writes to B by T2 happen after commit order → recoverable.

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Q18

Schedule: r1(A) w2(A) r3(A) w2(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 has invalid data.
• Schedule is non-recoverable.

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Q19

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial → safe.
• T2 and T3 write → commit order respects read-from dependencies → recoverable.

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Q20

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted A from T1 → dependency chain.
• If T1 aborts, T2 must abort → T3 reads T2 → violates recoverability → non-recoverable.

Q21

Schedule: r1(A) r2(A) w2(A) c2 c1
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 writes A after reading initial → commits before T1.
• T1 read-from dependency violated? If T1 had read before T2 writes, fine, but T1 commits after T2 → depends on uncommitted? Here T1 reads A before T2 writes → safe.
• Wait carefully: T1 read A (initial) → T2 writes → T2 commits → T1 commits. Safe.
  ✅ Corrected Answer: A
  Solution: All read-from committed values → recoverable.

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Q22

Schedule: w1(A) r2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads A after T1 wrote → T1 committed first → read-from committed value.
• T3 writes A after T2 → all commits respect dependencies → recoverable.

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Q23

Schedule: r1(A) w2(A) r3(A) w2(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads A after T2 commits → safe.
• T1 reads before T2 writes → safe → recoverable.

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Q24

Schedule: r1(A) w2(A) r3(A) w2(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 has invalid data → violates recoverability → non-recoverable.

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Q25

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value (from T2) → safe.
• No transaction read uncommitted values → recoverable.

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Q26

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 read initial A → safe.
• T2 writes → T3 writes → commit order respects read-from dependencies → recoverable.

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Q27

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → violates recoverability → non-recoverable.

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Q28

Schedule: r1(A) r2(A) w2(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial → T2 writes → T3 writes B → commit order respects read-from dependencies → recoverable.

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Q29

Schedule: w1(A) r2(A) r3(A) w2(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads committed A from T1 → safe.
• T3 reads A after T1 → safe → recoverable.

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Q30

Schedule: r1(A) w2(A) r3(A) c3 c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T3 reads A before T2 commits → read-from uncommitted → if T2 aborts, T3 invalid → violates recoverability → non-recoverable.

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Q31

Schedule: w1(A) r2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads committed value from T1 → safe → recoverable.

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Q32

Schedule: r1(A) r2(A) w2(A) w3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 depends on T2 → violates recoverability → non-recoverable.

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Q33

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value (T2) → safe → recoverable.

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Q34

Schedule: r1(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value from T2 → safe.
• T1 reads before T2 → safe → recoverable.

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Q35

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → violates recoverability → non-recoverable.

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Q36

Schedule: w1(A) r2(A) r3(A) w2(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T2 reads committed A from T1 → safe.
• T3 reads A after T1 → safe → recoverable.

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Q37

Schedule: r1(A) w2(A) r3(A) c3 c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T3 reads before T2 commits → read-from uncommitted → violates recoverability → non-recoverable.

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Q38

Schedule: r1(A) r2(A) w2(A) c1 c2
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial → safe.
• T2 writes → commits → dependencies respected → recoverable.

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Q39

Schedule: w1(A) r2(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted A from T1 → potential abort → T3 reads T2 → violates recoverability → non-recoverable.

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Q40

Schedule: r1(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe.
• T1 read before T2 → safe → recoverable.

Q41

Schedule: w1(A) r2(A) r3(A) w2(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → invalid data.
• T3 commit depends on aborted T2 → non-recoverable schedule.

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Q42

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial → safe.
• T2 writes → T3 writes → commit order respects read-from → recoverable.

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Q43

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads after T2 committed → read-from committed data → recoverable.

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Q44

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → violates recoverability → non-recoverable.

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Q45

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value from T2 → safe → recoverable.

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Q46

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads after T2 committed → safe.
• T1 reads initial → safe → recoverable.

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Q47

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q48

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted A from T1 → T2 commit depends on T1.
• T3 reads T2 → chain of dependencies → violates recoverability → non-recoverable.

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Q49

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads A after T2 committed → safe.
• T1 reads before T2 → safe → recoverable.

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Q50

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q51

Schedule: w1(A) r2(A) r3(A) w2(B) c1 abort2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q52

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial → safe.
• T2 and T3 writes respect commit order → recoverable.

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Q53

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads after T2 committed → read-from committed → recoverable.

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Q54

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q55

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value from T2 → recoverable.

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Q56

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All read-from dependencies respect committed values → recoverable.

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Q57

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q58

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted A from T1 → chain → violates recoverability → non-recoverable.

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Q59

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

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Q60

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 invalid → non-recoverable.

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Q61

Schedule: w1(A) r2(A) r3(A) w2(B) c1 abort2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

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Q62

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All read-from dependencies on committed values → recoverable.

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Q63

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

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Q64

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → violates recoverability → non-recoverable.

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Q65

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value → recoverable.

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Q66

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All reads from committed values → safe → recoverable.

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Q67

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → violates recoverability → non-recoverable.

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Q68

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted from T1 → T2 → T3 → chain violates recoverability → non-recoverable.

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Q69

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads after T2 committed → safe → recoverable.

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Q70

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → violates recoverability → non-recoverable.

Q71

Schedule: w1(A) r2(A) r3(A) w2(B) c1 abort2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 read-from T2 → T3 has invalid data.
• Commit chain depends on aborted T2 → non-recoverable.

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Q72

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T1 reads initial A → safe.
• T2 writes → T3 writes → commit order respects dependencies → recoverable.

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Q73

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value from T2 → safe → recoverable.

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Q74

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → T3 invalid → non-recoverable.

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Q75

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value → recoverable.

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Q76

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All read-from committed values → safe → recoverable.

---

Q77

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

---

Q78

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted value from T1 → chain of dependencies → violates recoverability → non-recoverable.

---

Q79

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

---

Q80

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → invalid → non-recoverable.

---

Q81

Schedule: w1(A) r2(A) r3(A) w2(B) c1 abort2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 aborts → T3 depends on T2 → violates recoverability → non-recoverable.

---

Q82

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All read-from dependencies respect committed values → recoverable.

---

Q83

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

---

Q84

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → T3 invalid → non-recoverable.

---

Q85

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value → recoverable.

---

Q86

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All reads are from committed values → recoverable.

---

Q87

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

---

Q88

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted from T1 → chain violates recoverability → non-recoverable.

---

Q89

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

---

Q90

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

---

Q91

Schedule: w1(A) r2(A) r3(A) w2(B) c1 abort2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → non-recoverable.

---

Q92

Schedule: r1(A) r2(A) w2(A) w3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• Commit order respects read-from dependencies → recoverable.

---

Q93

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → recoverable.

---

Q94

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → non-recoverable.

---

Q95

Schedule: w1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads final committed value → recoverable.

---

Q96

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• All reads from committed values → recoverable.

---

Q97

Schedule: r1(A) r2(A) w2(A) r3(A) w3(B) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

---

Q98

Schedule: w1(A) r2(A) w2(A) r3(A) w3(B) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 reads uncommitted from T1 → chain → violates recoverability → non-recoverable.

---

Q99

Schedule: r1(A) w2(A) r3(A) c1 c2 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: A
Solution:

• T3 reads committed value → safe → recoverable.

---

Q100

Schedule: r1(A) w2(A) r3(A) abort2 c1 c3
A. Recoverable
B. Non-recoverable
C. Cascadeless
D. Strict

✅ Answer: B
Solution:

• T2 abort → T3 read-from T2 → violates recoverability → non-recoverable.

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