Bissoy.com
Doctors Medicines MCQs Q&A

Consider the following two statements about database transaction schedules: I. Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable. II. Timestamp-ordering concurrency control protocol with Thomas’ Write Rule can generate view serializable schedules that are not conflict serializable. Which of the above statements is/are TRUE?

Consider the following two statements about database transaction schedules: I. Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable. II. Timestamp-ordering concurrency control protocol with Thomas’ Write Rule can generate view serializable schedules that are not conflict serializable. Which of the above statements is/are TRUE? Correct Answer Both I and II

Strict 2PL allows only schedules whose precedence graph is acyclic i.e. schedule is Conflict Serial.

In 2PL, transactions do not release exclusive locks until the transaction has committed or aborted i.e. schedule is recoverable.

Time stamp ordering schedule with Thomas write rule generate View serial schedule with BLIND WRITE. Because of BLIND WRITE it won't be Conflict Serial.

Option 3 is correct.

Related Questions

Consider the following partial Schedule S involving two transactions T1 and T2. Only the read and the write operations have been shown. The read operation on data item P is denoted by read(P) and the write operation on data item P is denoted by write(P) Time Instance Transaction-id T1 T2 1 read(A)   2 write(A)   3   read(C) 4   write(C) 5   read(B) 6   write(B) 7   read(A) 8   Commit 9 read(B)     Schedule S   Suppose that the transaction T1 fails immediately after time instance 9. Which one of the following statements is correct?
With reference to technologies for solar power production, consider the following statements: 1. 'Photovoltaics' is a technology that generates electricity by direct conversion of light into electricity, while 'Solar Thermal' is a technology that utilizes the Sun's rays to generate heat which is further used in the electricity generation process. 2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC). 3. India has a manufacturing base for Solar Thermal technology, but not for Photovoltaics. Which of the statements given above is/are correct?
In a database system, unique timestamps are assigned to each transaction using Lamport’s logical clock. Let TS(T1) and TS(T2) be the timestamps of transactions T1 and T2 respectively. Besides, T1 holds a lock on the resource R, and T2 has requested a conflicting lock on the same resource R. The following algorithm is used to prevent deadlocks in the database system assuming that a killed transaction is restarted with the same timestamp. If TS(T2) < TS(T1) then T1 is killed else T2 waits. Assume any transaction that is not killed terminates eventually. Which of the following is TRUE about the database system that uses the above algorithm to prevent deadlocks?
You are the administrator of a SQL Server 2000 computer. The server contains a database named FinanceData that is used by a client/server application. Each employee has a SQL Server login that the application uses to access the server.Your company hires a new employee named Andrew. You create a SQL Server login named Andrew. You also create a database user named Andrew in the database and grant the database user full permissions in the database.Whenever Andrew runs the client/server application, he receives the following error message: "Invalid object name." Andrew also reports that he cannot access the database by using the application.You need to ensure that Andrew can use the application. Which Transact-SQL statement should you execute?
State true or false: The Thomas write rule has a greater potential concurrency than the timestamp ordering protocol
State true or false: Serializable level may allow both serializable and non-serializable executions
Which of the following statements is/are true/false regarding modes of Conflict Management Styles?
1. The avoidance modes of conflict management aim at avoiding or postponing conflicts.
2. The compromise mode involves coercion and is likely to fail to reach a solution.
3. The main objective of the defusion mode of conflict resolution is to buy time for dealing with a conflict.
4. Withdrawal is a form of approach mode that involves getting away from a conflict situation.
Consider the following schedule for transactions T1, T2 and T3: T1                  T2                    T3 Read(X)                              Read(Y)                                                Read(Y)                       Write(Y) Write(X)                                                 Write(X)                       Read(X)                       Write(X) Which one of the schedules below is the correct serialization of the above?
Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item x, denoted by r(x) and w(x) respectively. Which one of them is conflict serializable?
Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item X, denoted by r(X) and w(X) respectively. Which one of them is conflict serializable ? S1 : r1(X); r2(X); w1(X); r3(X); w2(X) S2 : r2(X); r1(X); w2(X); r3(X); w1(X) S3 : r3(X); r2(X); r1(X); w2(X); w1(X) S4 : r2(X); w2(X); r3(X); r1(X); w1(X)