# Recent questions tagged transactions

1 vote
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Consider thw following schedules :- S1 :- W1(A) W2(A) W1(B) W2(B) S2:- W1(A) R2(A) W2(A) W2(B) W1(B) Assume that schedule S1 is failed after performing W1(B). Which of the following options are true? a.) S1 and S2 has lost update problem and WW ... free from lost update problem and WW problem c) S1 has WW problem and S2 has lost update problem d) S1 has lost update problem and s2 has WW problem
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True / false? 1. Serial schedules don't have any conflicting pairs. 2. Serializable schedules don't have any conflicting pairs
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Consider thw following transactions:- T1 :- r1(A) w1(A) r1(B) w1(B) T1 :- r2(A) w2(A) r2(B) w2(B) a) Number of schedules serializable as t1->t2? b) Number of schedules serializable as t2->t1?
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Number of schedules view equal to following schedule :- r1(A), w1(B), r2(A), w2(B), r3(A), w3(B)
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ACID properties of a transactions are Atomicity, consistency, isolation, database Atomicity, consistency, isolation, durability Atomicity, consistency, integrity, durability Atomicity, consistency, integrity, database
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Which of the following concurrency control protocol ensures both conflict and free from deadlock? , Time stamp ordering 2 Phase locking Both (a) and (b) None of the above
1 vote
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Consider the following schedules: S1: W2(x), W1(x), R3(x), R1(x), W2(y), R3(y), R3(z), R2(x) S2: R3(z), W2(x), W2(y), R1(x), R3(x), R2(z), R3(y), W1(x) S3: R2(z), W2(x), W2(y), W1(x), R1(x), R3(x), R3(z), R3(y) Which one of the above schedules are conflict equivalent?
1 vote
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What is the difference between Pessimistic time stamp ordering and optimistic time stamp ordering.
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What is the advantage and drawback of Multiversion Timestamp ordering in comparison with ordering Time stamp ordering? anyone please also explain what is this multiversion Timestamp ordering and what is the Timestamp ordering in simple words please?
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In two phase Commit Protocol,why can blocking be completely eliminated even when participants elect a new Coordinator ?
1 vote
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Essential differences in the Lock based Protocols and Time-stamp based proctols?
1 vote
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Somebody please explain this i am not able to understand please given an example of transaction or explain in hindi what the question and answer is please explain somebody please Here i am posting the Entire Question with some Multiple Choices and a Perfect Example now please somebody please explain which choice is correct and which is wrong I am not able to understand it.
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Two transactions $T_1$ and $T_2$ are given as $T_1:r_1(X)w_1(X)r_1(Y)w_1(Y)$ $T_2:r_2(Y)w_2(Y)r_2(Z)w_2(Z)$ where $r_i(V)$ denotes a $\textit{read}$ operation by transaction $T_i$ on a variable $V$ and $w_i(V)$ denotes a $\textit{write}$ operation by transaction $T_i$ on a variable $V$. The total number of conflict serializable schedules that can be formed by $T_1$ and $T_2$ is ______
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I)All schedules that are allowed under 2PL are also allowed under Timestamp?? Is vice versa true?? II)Plz explain by giving example. I have read that there are schedules that are allowed under 2PL but not under Timestamp and vice versa, but need example. ... in Timestamp??? IV) Are all view serializable allowed under Timestamp(Thomas write rule)??? Explanation along with example would be helpful.
1 vote
15
IS CONSERVATIVE 2PL ALSO RIGOROUS?? WHEN WE SAY THAT A TRANSACTION FOLLOWS CONSERVATIVE TWO PHASE LOCKING, DOES IT AUTOMATICALLY ALSO IMPLY RIGOROUS 2PL??
1 vote
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1 vote
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S: R1(A), R3(D), W1(B), R2(B), R4(B), W2(C), R5(C), W4(E), R5(E), W5(B) Number of serial schedules which are view equal to above S are __. Polygraph that I drew:
1 vote
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Whether the given schedule is conflict serializable or view serializable or none.
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$S: R_1(A),R_2(B),W_2(A),W_3(C),R_4(C),R_3(A),W_3(B),R_4(A),W_2(B),W_4(B),W_3(A)$ View serializable or not?
1 vote
20
Do commit operations matter while checking serilizability?If yes why?
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Here T1 T2 T4 T5 will come in this order only and for T3 we have 5 positions So number of schedules will be 5 which are view eq to given schedule. But ans given is 10
1 vote
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Consider the following schedule S : r1(A) w2(A) r3(A) w4(A) r5(A) w6(A) The number of schedules equal to given schedule(s) which not conflict equal to schedule(s) are _______.
1 vote
24
Statement # 5 is correct or not? how?
1 vote
25
I know that every schedule produced by the Timestamp-based protocol is conflict serializable. But is vice versa is true? Means is all conflict serializable schedules produced by timestamp based protocol ?