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Showing posts with label DSSSB. Show all posts
Showing posts with label DSSSB. Show all posts

## Friday 20 August 2021

### Conflict Serializability Assignment - S P SHARMA CLASSES

Question : Consider the following schedules involving two transactions. Which one of the following statement is true?

S1: R1(X) R1(Y) R2(X) R2(Y) W2(Y) W1(X)
S2: R1(X) R2(X) R2(Y) W2(Y) R1(Y) W1(X)

• Both S1 and S2 are conflict serializable
• Only S1 is conflict serializable
• Only S2 is conflict serializable
• None

Question 2 : Consider the following schedules involving two transactions. Which one of the following statement is true?

S1: r1(x) r1(y) w2(x) w1(x) r2(y)
S2: r1(x) r3(y) w1(x) w2(y) r3(x) w2(x)

• Both S1 and S2 are conflict serializable
• Only S1 is conflict serializable
• Only S2 is conflict serializable
• None
Question 3 : Consider the following schedules involving three transactions. Which one of the following statement is true?
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?
(A) Only S1 is conflict-serializable.
(B) Only S2 is conflict-serializable.
(C) Both S1 and S2 are conflict-serializable.
(D) Neither S1 nor S2 is conflict-serializable.

Question 4 : Let $S$ be the following schedule of operations of three transactions  and  in a relational database system:



Consider the statements $P$ and $Q$ below:

•  is conflict-serializable.
• : If  commits before  finishes, then  is recoverable.

Which one of the following choices is correct?

1. Both  and are true
2.  is true and  is false
3.  is false and  is true
4. Both  and  are false

1. C
2. C
3. A
4. B