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DBMS Concurrency Control MCQs

DBMS Concurrency Control MCQs: This section contains multiple-choice questions and answers on Concurrency Control in DBMS.
Submitted by Anushree Goswami, on April 18, 2022

1. A management procedure called ___ control is required to control the process of concurrently performing operations on a database.

Database
Conspiracy
Concurrency
Relational

Answer: C) Concurrency

Explanation:

A management procedure called concurrency control is required to control the process of concurrently performing operations on a database.

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2. The concurrent execution of the database in a ____-user system refers to the fact that multiple users are able to access and use it at the same time.

Single
Two
Three
Multiple

Answer: D) Multiple

Explanation:

The concurrent execution of the database in a multi-user system refers to the fact that multiple users are able to access and use it at the same time.

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3. When dealing with database transactions, there is often a need for multiple users to use a database to perform different operations. In this case, ___ of the database occurs.

Concurrent Connection
Concurrent Reduction
Concurrent Execution
Concurrent Revolution

Answer: C) Concurrent Execution

Explanation:

When dealing with database transactions, there is often a need for multiple users to use a database to perform different operations. In this case, concurrent execution of the database occurs.

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4. During simultaneous execution, each operation should be performed interleaved with the others, ensuring that there is no interference with the other operations. This maintains a database ___.

Consistency
Redundancy
Concurrency
None

Answer: C) Concurrency

Explanation:

During simultaneous execution, each operation should be performed interleaved with the others, ensuring that there is no interference with the other operations. This maintains database consistency.

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5. What are the two main operations in the database transaction?

READ
WRITE
Both A and B
None of the above

Answer: C) Both A and B

Explanation:

The two main operations in the database transactions are READ and WRITE.

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6. How many concurrency problems are there?

Answer: B) 5

Explanation:

5 concurrency problems are there.

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7. Which of the following is a concurrency problem?

Temporary Update Problem
Incorrect Summary Problem
Lost Update Problem
All of the above

Answer: D) All of the above

Explanation:

These are the concurrency problems -

Temporary Update Problem
Incorrect Summary Problem
Lost Update Problem
Unrepeatable Read Problem
Phantom Read Problem

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8. What is the Lost Update Problem also known as?

W-W Conflict
W-R Conflict
R-R Conflict
None

Answer: A) W-W Conflict

Explanation:

Lost Update Problem is also known as W-W Conflict.

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9. This occurs when more than one database transaction attempts to read or write the same database item simultaneously (i.e., concurrent execution), causing the values of the item to become incorrect, resulting in a/an ___ database.

Consistent
Inconsistent
Concurrent
Not-concurrent

Answer: B) Inconsistent

Explanation:

This occurs when more than one database transaction attempts to read or write the same database item simultaneously (i.e., concurrent execution), causing the values of the item to become incorrect, resulting in an inconsistent database.

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10. What is the Dirty Read Problem also known as?

W-W Conflict
W-R Conflict
R-R Conflict
None

Answer: B) W-R Conflict

Explanation:

Dirty Read Problem is also known as W-R Conflict.

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11. When one transaction updates a database item, and somehow the transaction fails, and the data doesn't get ___ back, another transaction tries to access the updated database item.

Rolled
Committed
Aborted
None

Answer: A) Rolled

Explanation:

When one transaction updates a database item, and somehow the transaction fails, and the data doesn't get rolled back, another transaction tries to access the updated database item.

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12. What is the Unrepeatable Read Problem also known as?

Consistent Retrieval Problems
Inconsistent Retrieval Problems
Concurrent Retrieval Problems
Non-concurrent Retrieval Problems

Answer: B) Inconsistent Retrieval Problems

Explanation:

The Unrepeatable Read Problem is also known as Inconsistent Retrieval Problems.

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13. An unrepeatable read problem occurs when the same database item is read ____ during a transaction.

Once
Twice
Thrice
Multiple

Answer: B) Twice

Explanation:

An unrepeatable read problem occurs when the same database item is read twice during a transaction.

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14. ___ concurrent database operations are required for avoiding inconsistencies in a database by utilizing the concurrency control concept.

Controlling
Managing
Both A and B
None of the above

Answer: C) Both A and B

Explanation:

Controlling and managing concurrent database operations are required for avoiding inconsistencies in a database by utilizing the concurrency control concept.

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15. The concurrency ___ allows us to maintain the concurrency of the database.