GATE CS 2014 Set 3 — Question 39
Go beyond PYQs with Success TrackerAI-powered personalised practice and doubt support. Unlimited practice on eligible plans; AI usage limits apply.MCQ+2 / -0.67MediumConflict SerializabilityTransactions & ConcurrencyDatabases
Databases → Transactions & Concurrency → Conflict Serializability
Last updated
Question
Consider the transactions , , and and the schedules and given below.Which one of the following statements about the schedules is TRUE?
T1: r1(X); r1(Z); w1(X); w1(Z)
T2: r2(Y); r2(Z); w2(Z)
T3: r3(Y); r3(X); w3(Y)
S1: r1(X); r3(Y); r3(X); r2(Y); r2(Z); w3(Y); w2(Z); r1(Z); w1(X); w1(Z)
S2: r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z)
Correct answer
(A) Only S₁ is conflict-serializable.
Solution
To determine conflict serializability, we construct the precedence graph for each schedule.For Schedule :
There are no cycles. Thus, is conflict-serializable.For Schedule :
This forms a cycle (). Thus, is NOT conflict-serializable.Therefore, only is conflict-serializable.
- comes before : Edge
- comes before : Edge
- comes before : Edge
- comes before : Edge
There are no cycles. Thus, is conflict-serializable.For Schedule :
- comes before : Edge
- comes before : Edge
- comes before : Edge
This forms a cycle (). Thus, is NOT conflict-serializable.Therefore, only is conflict-serializable.
Continue learning with Success Tracker
A step still unclear? Work through it with support
Use Success Tracker to ask about the reasoning, then try another GATE CS question to check your understanding.
AI-powered practice· Unlimited practice on eligible plans
- PYQs with solutions
- Attempt available previous-year questions, then compare your reasoning with the worked solution. Coverage varies by stream.
- Practice that adapts
- Choose a topic, work on weaker areas and bookmark questions to revisit. Your attempts feed your progress tracking.
- AI doubt support
- Ask follow-up questions about a step or concept while practising, instead of stopping at the final answer.
Unlimited practice is available on eligible plans. Free practice and AI usage have limits; check the current plan allowances before choosing.
This page stays readable without an account. AI responses can be wrong; check them against the solution and source material.
More questions on Transactions & Concurrency
2026 Set 2 Q15In the context of DBMS, consider the two sets T and S given below. | T | S | |---|---| | I:…2026 Set 2 Q20Consider concurrent execution of two transactions and in a DBMS, both of which access a…2026 Set 1 Q30Let and be the attributes of a relation in a relational schema. Let…2026 Set 1 Q31In the context of relational database normalization, which of the following statements is/are true?2026 Set 2 Q42In the context of schema normalization in relational DBMS, consider a set F of functional…