1
GATE CSE 2012
MCQ (Single Correct Answer)
+2
-0.6
Consider the following transactions with data items P and Q initialized to zero:
T1 : read (P) ;
read (Q) ;
if P = 0 then Q : = Q + 1 ;
write (Q).
T2 : read (Q) ;
read (P)
if Q = 0 then P : = P + 1 ;
write (P).
Any non-serial interleaving of T1 and T2 for concurrent execution leads to2
GATE CSE 2010
MCQ (Single Correct Answer)
+2
-0.6
Consider the following schedule for transactions T1, T2 and T3:
Which one of the schedules below is the correct serialization of the above?
3
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Consider two transactions T1 and T2 and four schedules S1, S2, S3, S4 of T1 and T2
as given below:
T1: R1[ x ] W1[ x ] W1[ y ]
T2: R2[ x ] R2[ y ] W2[ y ]
S1: R1[ x ] R2[ x ] R2[ y ] W1[ x ] W1[ y ] W2[ y ]
S2: R1[ x ] R2[ x ] R2[ y ] W1[ x ] W2[ y ] W1[ y ]
S3: R1[ x ] W1[ x ] R2[ x ] W1[ y ] R2[ y ] W2[ y ]
S4: R2[ x ] R2[ y ] R1[ x ] W1[ x ] W1[ y ] W2[ y ]
4
GATE CSE 2009
MCQ (Single Correct Answer)
+2
-0.6
Let R and S be relational schemes such that R = { a, b, c } and S = { c }. Now consider the following queries on the database:
I. $$\pi_{R-S}(r) - \pi_{R-S} \left (\pi_{R-S} (r) \times s - \pi_{R-S,S}(r)\right )$$
II. $$\left\{t \mid t \in \pi_{R-S} (r) \wedge \forall u \in s \left(\exists v \in r \left(u = v[S] \wedge t = v\left[R-S\right]\right )\right )\right\}$$
III.$$\left\{t \mid t \in \pi_{R-S} (r) \wedge \forall v \in r \left(\exists u \in s \left(u = v[S] \wedge t = v\left[R-S\right]\right )\right ) \right\}$$
IV. Select R.a, R.b
From R, S
Where R.c = S.c
Which of the above queries are equivalent?Questions Asked from Transactions and Concurrency (Marks 2)
Number in Brackets after Paper Indicates No. of Questions
GATE CSE 2021 Set 1 (2)
GATE CSE 2020 (1)
GATE CSE 2016 Set 2 (1)
GATE CSE 2016 Set 1 (1)
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GATE CSE 2015 Set 2 (1)
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GATE CSE 2014 Set 3 (1)
GATE CSE 2014 Set 1 (1)
GATE CSE 2012 (1)
GATE CSE 2010 (1)
GATE CSE 2009 (2)
GATE CSE 2008 (1)
GATE CSE 2007 (2)
GATE CSE 2004 (1)
GATE CSE 2003 (1)
GATE CSE 1999 (1)
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