Database Concurrency Management

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What is the primary objective of serializability?

To ensure that concurrent transactions do not interfere with each other. (correct)

To ensure that all transactions are executed in a serial manner.

To allow transactions to execute concurrently without affecting the database state.

To prevent deadlocks from occurring in concurrent transactions.

What is the purpose of applying rule 6 in creating a graph to determine serializability?

To identify potential deadlocks in the schedule

To ensure that the transactions are recoverable

To produce a graph that contains only one edge

To determine the view serializability of a schedule (correct)

What happens if two transactions only read a data item?

They starve other transactions from accessing the data item.

They do not conflict and the order of execution is not important. (correct)

They cause a deadlock and must be rolled back.

They conflict and the order of execution is important.

What is the result of serial execution?

The database state is consistent and correct. Signup and view all the answers

Why do DBMSs not test for the serializability of a schedule?

Because it is impractical to test for serializability Signup and view all the answers

What is a correct nonserial schedule called?

Serializable. Signup and view all the answers

What is the purpose of using protocols that are known to produce serializable schedules?

To ensure the consistency of the database Signup and view all the answers

What is the requirement of the atomicity property in the event of a transaction failure?

To undo the effects of the transaction Signup and view all the answers

Why is it essential to guarantee serializability of concurrent transactions?

To prevent inconsistency from transactions interfering with one another. Signup and view all the answers

What is the implication of the durability property on a committed transaction?

Its changes cannot be undone without running another, compensating, transaction Signup and view all the answers

What is important in the ordering of read and write operations?

The order of execution is only important when one transaction writes and another reads the same data item. Signup and view all the answers

What is the relationship between serializability and recoverability?

Recoverability is a subset of serializability Signup and view all the answers

What is a necessary condition for two schedules to be considered view equivalent?

They must consist of the same operations from n transactions. Signup and view all the answers

If a transaction Ti reads the initial value of a data item x in schedule S1, what must it do in schedule S2?

It must also read the initial value of x. Signup and view all the answers

What is true about every conflict serializable schedule?

It is view serializable. Signup and view all the answers

What is a characteristic of a view serializable schedule that is not conflict serializable?

It contains one or more blind writes. Signup and view all the answers

What is the relationship between view serializability and conflict serializability?

Every conflict serializable schedule is view serializable. Signup and view all the answers

What is the purpose of the concept of view serializability?

To provide a less restrictive definition of serializability. Signup and view all the answers

Database Concurrency Management

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