1
GATE CSE 2016 Set 2
MCQ (Single Correct Answer)
+2
-0.6
Consider the following database schedule with two transactions, T1 and T2
 S = r2(X); r1(X); r2(Y); w1(X); r1(Y); w2(X); a1; a2

where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti .

Which one of the following statements about the above schedule is TRUE?

A
S is non-recoverable
B
S is recoverable, but has a cascading abort
C
S does not have a cascading abort
D
S is strict
2
GATE CSE 2016 Set 1
MCQ (Single Correct Answer)
+2
-0.6
Consider the following two phase locking protocol. Suppose a transaction $$T$$ accesses (for read or write operations), a certain set of objects $$\left\{ {{O_1},...,{O_k}} \right\}.$$ This is done in the following manner:

Step 1. T acquires exclusive locks to $${{O_1},...,{O_k}}$$ in increasing order of their
addresses.
Step 2. The required operations are performed.
Step 3. All locks are released.

This protocol will

A
guarantee serializability and deadlock-freedom
B
guarantee neither serializability nor deadlock-freedom
C
guarantee serializability but not deadlock-freedom
D
guarantee deadlock-freedom but not serializability
3
GATE CSE 2015 Set 3
MCQ (Single Correct Answer)
+2
-0.6
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 $$(P).$$ GATE CSE 2015 Set 3 Database Management System - Transactions and Concurrency Question 13 English

Suppose that the transaction $$T1$$ fails immediately after time instance $$9.$$ Which one of the following statements is correct?

A
$$T2$$ must be aborted and then both $$T1$$ and $$T2$$ must be re-started to ensure transaction atomicity
B
Schedule $$S$$ is non-recoverable and cannot ensure transaction atomicity
C
Only $$T2$$ must be aborted and then re-started to ensure transaction atomicity
D
Schedule $$S$$ is recoverable and can ensure atomicity and nothing else needs to be done
4
GATE CSE 2015 Set 2
MCQ (Single Correct Answer)
+2
-0.6
Consider a simple checkpointing protocol and the following set of operations in the log.

(start, $$T4$$); (write, $$T4, y, 2, 3$$); (start, $$T1$$); (commit, $$T4$$); (write, $$T1, z, 5, 7$$);
(checkpoint);
(start, $$T2$$); (write, $$T2, x, 1, 9$$); (commit, $$T2$$); (start, $$T3$$), (write, $$T3, z, 7, 2$$);

If a crash happens now and the system tries to recovver using both undo and redo operations, what are the contents of the undo list and the redo list?

A
Undo: $$T3,T1;$$ Redo: $$T2$$
B
Undo: $$T3,T1;\,{\mathop{\rm Re}\nolimits} do:T2,T4$$
C
Undo: none; Redo: $$T2,T4,T3,T1$$
D
Undo: $$T3,T1,T4;\,\,$$ Redo : $$T2$$
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