Concurrency Control Quiz

What is the objective of concurrency control in a multiuser database environment?

• Encourage inconsistent retrievals

• Ensure the serializability of transactions

• Allow for lost updates

• Increase data integrity problems

What is the main problem associated with Lost Update in concurrency control?

• Retrievals become inconsistent

• Data becomes uncommitted

• One of the updates is lost

• Data integrity is compromised

When does the phenomenon of uncommitted data occur in concurrency control?

• When data is read before and after another transaction updates it

• When one transaction is rolled back after another has accessed the data

• When two transactions update the same data element

• When data integrity is compromised

What happens in the case of Inconsistent Retrievals in concurrency control?

• Transactions access data before and after it is changed

• Transactions lose updates

• Data becomes uncommitted

• Data integrity is compromised

What is the main job of the scheduler in a multiuser database system?

• Assign and police locks used by transactions

• Create a serializable schedule of a transaction's operations

• Enforce locking procedures

• Manage lock information

At what level does a page-level lock operate in concurrency control?

• A row

• An entire table

• A field

• An entire diskpage

What is the main disadvantage of the time stamping method in concurrency control?

• Increases memory needs and processing overhead

• Causes inconsistent retrievals

• Leads to lost updates

• Requires high overhead for row-level locking

What is the purpose of the wait/die scheme in managing concurrent transaction execution?

• The younger transaction waits for the older to complete

• Both transactions are rolled back

• Both transactions wait indefinitely

• The older transaction waits for the younger to complete

What is the main goal of deadlock prevention in concurrency control?

• Avoid conditions that lead to deadlocking

• Detect deadlocks periodically

• Preempt younger transactions

• Wait for older transactions to complete

What is the primary function of a shared lock in concurrency control?

• Grant read access to concurrent transactions

• Rollback transactions

• Preempt younger transactions

• Reserve access for the locking transaction