1
GATE CSE 2007
+2
-0.6
Consider the following schedules involving two transactions. Which one of the following statements is TRUE?

S1: r1(X); r1(Y); r2(Y); r2(X); w2(Y); w1(X);

S2: r1(X); r2(X); r2(Y); w2(Y); r1(Y); w1(X);

A
Both S1 and S2 are conflict serializable.
B
S1 is conflict serializable and S2 is not conflict serializable.
C
S1 is not conflict serializable and S2 is conflict serializable.
D
Both S1 and S2 are not conflict serializable.
2
GATE CSE 2007
+2
-0.6
Consider the following two transactions: T1 and T2.
T1: read (A);                  T2: read (B);
if A = 0 then B ← B + 1;       if B ≠ 0 then A ← A - 1;
write (B);                     write (A);
Which of the following schemes, using shared and exclusive locks, satisfy the requirements for strict two phase locking for the above transactions?
A
S1 : lockS(A); 	        S2 : lockS(B);
lockS(B);               lockS(A);
if A = 0                if B ≠ 0
then B ← B + 1;        then A ← A - 1;
write (B);              write (A);
commit;                 commit;
unlock (A);             unlock (B);
unlock (B);             unlock (A);
B
S1 : lockX(A);          S2 : lockX(B);
lockX(B);               lockX(A);
if A = 0                if B ≠ 0
then B ← B + 1;        then A ← A - 1;
write (B);              write (A);
unlock (A);             unlock (A);
commit;                 commit;
unlock (B);             unlock (A);
C
S1 : lockS(A);           S2 : lockS(B);
lockX(B);                lockX(A);
if A = 0                 if B ≠ 0
then B ← B + 1;         then A ← A - 1;
write (B);               write (A);
unlock (A);              unlock (B);
commit;                  commit;
unlock (B);              unlock (A);
D
S1 : lockS(A);           S2 : lockS(B);
lockX(B);                lockX(A);
if A = 0                 if B ≠ 0
then B ← B + 1;        then A ← A - 1;
write (B);               write (A);
unlock (A);              unlock (A);
unlock (B);              unlock (B);
commit;                  commit;
3
GATE CSE 2004
+2
-0.6
Consider the following schedule S of transactions T1 and T2: Which of the following is TRUE about the schedule S?
A
S is serializable only as T1,T2
B
S is serializable only as T2,T1
C
S is serializable both as T1, T2 and T2, T2
D
S is not serializable either as T1 or as T2
4
GATE CSE 2003
+2
-0.6
Consider three data items D1, D2, and D3, and the following execution schedule of transactions T1, T2, and T3. In the diagram, R(D) and W(D) denote the actions reading and writing the data item D respectively.

Which of the following statements is correct?

A
The schedule is serializable as T2; T3; T1
B
The schedule is serializable as T2; T1; T3
C
The schedule is serializable as T3; T2; T1
D
The schedule is not serializable
GATE CSE Subjects
EXAM MAP
Medical
NEET