Bissoy.com
Doctors Medicines MCQs Q&A

Consider the transactions T1, T2, and T3 and the schedules S1 and S2 given below. T1: r1(X); r1(Z); w1(X); w1(Z) T2: r2(Y); r2(Z); w2(Z) T3: r3(Y); r3(X); w3(Y) S1: r1(X); r3(Y); r3(X); r2(Y); r2(Z); w3(Y); w2(Z); r1(Z); w1(X); w1(Z) S2: r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z) Which one of the following statements about the schedules is TRUE?

Consider the transactions T1, T2, and T3 and the schedules S1 and S2 given below. T1: r1(X); r1(Z); w1(X); w1(Z) T2: r2(Y); r2(Z); w2(Z) T3: r3(Y); r3(X); w3(Y) S1: r1(X); r3(Y); r3(X); r2(Y); r2(Z); w3(Y); w2(Z); r1(Z); w1(X); w1(Z) S2: r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z) Which one of the following statements about the schedules is TRUE? Correct Answer Only S1 is conflict-serializable

Concept:

  • Using precedence graph method, we can find out Schedule is conflict serializable or not.
  • If precedence graph has any loop then that schedule is going to be not conflict-serializable.
  • If precedence graph doesn’t have any loop then that schedule is going to be conflict-serializable.


Explanation:

Schedule S1:

T1

T2

T3
r(X)    

 

 

r(Y)

 

 

r(X)

 

r(Y)

 

 

r(Z)

 

 

 

w(Y)

 

w(Z)

 

r(Z)

 

 

w(X)

 

 

w(Z)

 

 
     

 

Precedence graph of S1:

Since there is no loop in S1, it is is conflict serializable

Order: T2 → T1 → T2

Schedule S2: 

r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z)

T1

T2

T3
r(X)    

 

 

r(Y)

 

r(Y)

 

 

 

r(X)

r(Z)

 

 

 

r(Z)

 

 

 

w(Y)

w(X)

 

 

 

w(Z)

 

w(Z)

 

 

 

Precedence graph of S2:

[ alt="F1 Raju Madhu 17.07.20 D2" src="//storage.googleapis.com/tb-img/production/20/07/F1_Raju_Madhu_17.07.20_D2.png" style="width: 131px; height: 103px;">

  • So there is loop in S2 so S2 is not conflict serializable.
  • Schedule S1 is equivalent to only this serial schedule T2 : T3 : T1.


Hence option 1 is the correct answer.

Related Questions

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?
A database has 5 transactions. Of these, 4 transactions include milk and bread. Further, of the given 4 transactions, 2 transactions include cheese. Find the support percentage for the following association rule "if milk and bread are purchased, then cheese is also purchased".
Indicate the correct code of the following statements being correct or incorrect. The statements relate to the type of transactions recorded in the current/capital accounts of the Balance of Payments. Statement (I) : The capital account consists of long-term capital transactions only. Statement (II) : The current account includes all transactions which give rise to or use up national income.
The logic problems in this set present you with three true statements: Fact 1, Fact 2 and Fact 3. Then you are given three more statements (labelled I, II, III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; or none of the statements could be true. Fact 1: Jessica has four children. Fact 2: Two of the children have blue eyes and two of the children have brown eyes. Fact 3: Half of the children are girls. If the fist three statements are facts, which of the following statement/(s) must also be a fact? I. At least one girl has blue eyes. II. Two of the children are boys. III. The boys have brown eyes. Choose the correct answer from the options given below:
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 Statements about Schedules of Indian Constitution i. The fourth Schedules deals with the allocation of seats of Rajya Sabha to Union Territories. ii. The eighth Schedule deals with languages recognized by the government of India. iii. The tenth Schedule contains the Anti-defection law.
The logic problems in this set present you with three true statements: Fact 1, Fact 2 and Fact 3. Then you are given three more statements (labelled I, II, III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; or none of the statements could be true. Fact 1: Pictures can tell a story. Fact 2: All storybooks have pictures. Fact 3: Some storybooks have both words and pictures. If the first three statements are facts, which of the following statement/(s) must also be a fact? I. Pictures can tell a story better than words can. II. The stories in storybooks are very simple. III. Some storybooks have both words and pictures. Choose the correct answer from the options given below:
The logic problems in this set present you with three true statements: Fact 1, Fact 2 and Fact 3. Then you are given three more statements (labelled I, II, III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; or none of the statements could be true. Fact 1: Most stuffed toys are stuffed with beans. Fact 2: There are stuffed bears and stuffed tigers. Fact 3: Some chairs are stuffed with beans. If the fist three statements are facts, which of the following statement/(s) must also be a fact? I. Only children's chairs are stuffed with beans. II. All stuffed tigers are stuffed with beans. III. Stuffed monkeys are not stuffed with beans. Choose the correct answer from the options given below:
The logic problems in this set present you with three true statements: Fact 1, Fact 2 and Fact 3. Then you are given three more statements (labelled I, II, III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; or none of the statements could be true. Fact 1: All hats have brims. Fact 2: There are black hats and blue hats. Fact 3: Baseball caps are hats. If the first three statements are facts, which of the following statement/(s) must also be a fact? I. All caps have brims. II. Some baseball caps are blue. III. Baseball caps have no brims. Choose the correct answer from the options given below:
The logic problems in this set present you with three true statements: Fact 1, Fact 2 and Fact 3. Then you are given three more statements (labelled I, II, III), and you must determine which of these, if any, is also a fact. One or two of the statements could be true; or none of the statements could be true. Fact 1: All chickens are birds. Fact 2: Some chickens are hens. Fact 3: Female birds lay eggs. If the first three statements are facts, which of the following statement/(s) must also be a fact? I. All birds lay eggs. II. Hens are birds. III. Some chickens are not hens. Choose the correct answer from the options given below: