Concurrency Control in DBMS

Questions and Answers

What is one primary disadvantage of implementing concurrency control in databases?

It requires additional overhead that can slow down performance. (correct)

It simplifies the transactional logic of the system.

It guarantees increased throughput under all conditions.

It eliminates the risk of deadlocks entirely.

How can deadlocks impact database transactions?

They ensure that all transactions are executed in parallel.

They can prevent transactions from completing due to circular dependencies. (correct)

They allow transactions to complete faster.

They reduce the complexity of managing transactions.

What effect does concurrency control have on user access in a database system?

It can limit the number of users or applications accessing the database at once. (correct)

It maximizes the number of simultaneous users.

It increases the responsiveness of the database.

It has no impact on user access rates.

What complicates the implementation of concurrency control in distributed systems?

The intricate nature of transactional logic in these systems. Signup and view all the answers

What inconsistency can arise from poorly managed concurrency control?

Rolling back transactions leading to inconsistent database states. Signup and view all the answers

What is a likely consequence of increased overhead from concurrency control?

Increased resource consumption and potential performance slowdown. Signup and view all the answers

What is the main purpose of concurrency control in a database management system?

To manage simultaneous operations without data interference. Signup and view all the answers

Which of the following best describes a locked-based protocol?

Each transaction must acquire locks before accessing or modifying data. Signup and view all the answers

What does atomicity in concurrency control protocols refer to?

A transaction's ability to be completed entirely or not at all. Signup and view all the answers

Which statement accurately reflects the role of timestamps in a timestamp-based protocol?

Each transaction's timestamp determines its priority in execution. Signup and view all the answers

How does concurrency control impact resource utilization?

It maximizes resource utilization by allowing parallel transaction execution. Signup and view all the answers

What is the significance of maintaining database consistency in concurrency control?

To ensure that transactions do not interfere with each other's data integrity. Signup and view all the answers

What does 'waiting time' refer to in the context of process execution?

The time a process is not executed due to resource unavailability. Signup and view all the answers

Which of the following features is NOT provided by concurrency control protocols?

Synchronization of unrelated processes Signup and view all the answers

Study Notes

Concurrency Control Overview

Manages simultaneous database operations while preventing data interference and inconsistency.
Essential for ensuring multiple processes can manipulate data without conflicts.

Concurrency Control Protocols

Set of rules designed to address concurrency issues while maintaining database consistency.
Achieves atomicity, consistency, isolation, durability, and serializability in transaction execution.

Types of Concurrency Control Protocols

Locked-Based Protocol: Requires transactions to acquire locks before accessing or modifying data items.
Timestamp-Based Protocol: Each transaction is assigned a timestamp indicating when it enters the system.

Advantages of Concurrency Control

Reduced Waiting Time: Allows processes to be in a ready state without long delays for system execution.
Improved Response Time: Decreases time needed for initial responses from the CPU.
Enhanced Resource Utilization: Enables multiple transactions to execute simultaneously, maximizing system resource use.
Increased Efficiency: Improves the output-to-input ratio, resulting in higher system efficiency.

Disadvantages of Concurrency Control

Overhead: Additional resource consumption and performance degradation due to lock management.
Deadlocks: Risk of circular dependencies where transactions wait on each other, hindering progress.
Reduced Concurrency: May limit simultaneous accesses, slowing performance under heavy load.
Complexity: Implementation can be complex, especially in distributed environments, raising development costs.
Inconsistency Risks: Potential for the database to become inconsistent, especially if transactions are rolled back or delayed.

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Description

This quiz explores the concept of concurrency control in database management systems. It examines how simultaneous operations are managed to prevent data inconsistency and ensure smooth transaction execution. Test your understanding of this critical aspect of DBMS.