Database Management: Deadlock and Resource Contention

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Questions and Answers

What is a deadlock in database management?

A state in which multiple operations can progress simultaneously

A state in which no operation can progress (correct)

A state in which all operations are running smoothly

A state in which all processes are completed

How is a deadlock defined?

As resources asking for different things at different times

As multiple resources working independently

As two different resources that require the same resource at the same time (correct)

As resources with no dependencies

What is the consequence of deadlock if not handled properly?

Additional locking leading to system failure (correct)

Improved resource allocation

Enhanced performance of the DBMS

Smooth operation of the DBMS

Why are deadlocks more prevalent in distributed environments?

Because the objects of access are distributed Signup and view all the answers

What is the role of prioritization and sequencing schemes in DBMSs?

To prevent two processes from being at the same point at the same time Signup and view all the answers

What can result from cyclic requests for resources in a distributed environment?

Deadlocks involving many processes Signup and view all the answers

What is deadlock?

A situation where one transaction is waiting for a resource which is locked by another transaction Signup and view all the answers

What is the popular approach to dealing with database deadlocks?

Deadlock detection Signup and view all the answers

What principle is deadlock detection based on?

One of the requests that caused the deadlock should be aborted Signup and view all the answers

Which approach involves setting a lock wait time period to terminate sessions waiting for locks?

None of the above Signup and view all the answers

In deadlock avoidance, how are resources granted to a packet?

Resources are granted only if the resulting global state is safe Signup and view all the answers

What does deadlock recovery strategy involve?

Deallocating resources and granting them to other packets upon deadlock detection Signup and view all the answers

How can deadlock prevention be achieved?

By reserving all the required resources before starting transaction Signup and view all the answers

What is the common technique in deadlock avoidance?

Establishing an ordering between resources and granting resources to each packet in decreasing order Signup and view all the answers

What happens if a session waits more than the preset lock wait time period for a lock to free up?

The session will be terminated Signup and view all the answers

Which strategy involves granting resources without any check?

Deadlock recovery Signup and view all the answers

Study Notes

Deadlocks in Database Management

A deadlock is a situation where two or more transactions are blocked, each waiting for the other to release a resource, resulting in a deadlock cycle.

Defining Deadlocks

A deadlock is defined as a circular wait condition, where each transaction is waiting for a resource held by another transaction.

Consequences of Deadlocks

If not handled properly, deadlocks can lead to system crashes, data loss, and decreased system performance.

Prevalence of Deadlocks in Distributed Environments

Deadlocks are more prevalent in distributed environments due to the increased complexity of resource allocation and synchronization across multiple systems.

Prioritization and Sequencing Schemes

Prioritization and sequencing schemes play a crucial role in DBMSs by preventing deadlocks by controlling the order of resource allocation and release.

Cyclic Requests for Resources

Cyclic requests for resources in a distributed environment can result in deadlocks, as each transaction waits for a resource held by another transaction.

Approaches to Dealing with Deadlocks

The popular approach to dealing with database deadlocks is to use a combination of deadlock detection and recovery strategies.

Deadlock Detection

Deadlock detection is based on the principle of detecting a circular wait condition, where each transaction is waiting for a resource held by another transaction.

Deadlock Recovery Strategies

Deadlock recovery strategies involve rolling back or aborting transactions to break the deadlock cycle, and then restarting the transactions.

Deadlock Prevention

Deadlock prevention can be achieved by using techniques such as resource ordering, resource preemption, and banker's algorithm.

Deadlock Avoidance

In deadlock avoidance, resources are granted to a packet only if it is safe to do so, i.e., the grant does not lead to a deadlock.

Common Technique in Deadlock Avoidance

The common technique in deadlock avoidance is to use a wait-die scheme, where a transaction waits for a resource and dies if it times out.

Lock Wait Time Period

If a session waits more than the preset lock wait time period for a lock to free up, the session is terminated, and the lock is released.

Granting Resources without Check

The optimistic approach involves granting resources without any check, which can lead to deadlocks if not managed properly.

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Description

Understand the concept of deadlock in database management and how it relates to resource contention. Explore the prioritization and sequencing schemes implemented in DBMS to prevent deadlock scenarios.