RDBMS Questions and Answers – Serializability

This set of RDBMS Multiple Choice Questions & Answers (MCQs) focuses on “Serializability”.

1. I and J are _________ if they are operations by different transactions on the same data item, and at least one of them is a write operation.
a) Conflicting
b) Overwriting
c) Isolated
d) Durable
View Answer

Answer: a
Explanation: I and J are conflicting if they are operations by different transactions on the same data item, and at least one of them is a write operation.

2. If a schedule S can be transformed into a schedule S’ by a series of swaps of non-conflicting instructions, then S and S’ are
a) Non conflict equivalent
b) Equal
c) Conflict equivalent
d) Isolation equivalent
View Answer

Answer: c
Explanation: If a schedule S can be transformed into a schedule S’ by a series of swaps of non-conflicting instructions, then S and S’ are conflict equivalent. Not all serial schedules are conflict equivalent to each other.

3. A schedule is __________ if it is conflict equivalent to a serial schedule.
a) Conflict serializable
b) Conflicting
c) Non serializable
d) None of the mentioned
View Answer

Answer: a
Explanation: A schedule is conflict serializable if it is conflict equivalent to a serial schedule. The concept of conflict equivalence leads to the concept.
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4. The set of ________ in a precedence graph consists of all the transactions participating in the schedule
a) Vertices
b) Edges
c) Directions
d) None of the mentioned
View Answer

Answer: a
Explanation: The set of vertices in a precedence graph consists of all the transactions participating in the schedule. Precedence graph is a simple and efficient way of determining conflict serializability of the schedule.

5. A ___________of the transactions can be obtained by finding a linear order consistent with the partial order of the precedence graph.
a) Serializability order
b) Direction graph
c) Precedence graph
d) Scheduling scheme
View Answer

Answer: a
Explanation: A Serializability order of the transactions can be obtained by finding a linear order consistent with the partial order of the precedence graph. This process is called as topological sorting.
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6. State true or false: If I = read(Q) and J = read(Q) then the order of I and J does not matter.
a) True
b) False
View Answer

Answer: a
Explanation: If I = read(Q) and J = read(Q) then the order of I and J does not matter because both I and J are read operations on the query.

7. State true or false: If I = read(Q) and J = write(Q) then the order of I and J does not matter.
a) True
b) False
View Answer

Answer: b
Explanation: If I = read(Q) and J = write(Q) then the order of I and J matters because both I and J are different operations on the query. The order of execution determines the state of the database that is being read or written.
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8. Which of the following is the most expensive method?
a) Timestamping
b) Plain locking
c) Predicate locking
d) Snapshot isolation
View Answer

Answer: c
Explanation: Predicate locking is the most expensive method and is generally not used in most databases.

Sanfoundry Global Education & Learning Series – RDBMS.

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To practice all areas of RDBMS, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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