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Recent questions tagged serializability

1 vote
1 answer
1
Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item $x$, denoted by $r(x)$ and $w(x)$respectively. Which one of them is conflict serializable? $r_1(x);r_2(x);w_1(x);r_3(x);w_2(x)$ $r_2(x);r_1(x);w_2(x);r_3(x);w_1(x)$ $r_3(x);r_2(x);r_1(x);w_2(x);w_1(x)$ $r_2(x);w_2(x);r_3(x);r_1(x);w_1(x)$ $1$ $2$ $3$ $4$
asked Mar 30, 2020 in Databases Lakshman Patel RJIT 218 views
0 votes
0 answers
2
A' is set of all possible schedules 'C' is set of all possible schedules that are guaranteed to produce a correct final result 'S' is the set of all serializable schedules 'P' is the set of all schedules possible under 2-phase locking protocol Which is FALSE? $P\subseteq C$ $S\subset P$ $S\subseteq P$ $P\subset C$
asked May 28, 2019 in Databases aditi19 342 views
1 vote
0 answers
3
Consider the following schedules with data item x The number of serial schedules which are view equal to schedules but not conflict equal is ___________.
asked May 5, 2019 in Databases Hirak 273 views
0 votes
2 answers
4
I am getting the answer as c but the given answer is b. How b can be ans, there is a cycle R1x->W1x (s1->s2) and W1y->w1y(s2->s1),so s1,s2 can not be conflict serializable… i m confused.. what is the right answer?
asked Feb 24, 2019 in Databases debasree88 270 views
1 vote
1 answer
5
A schedule S contains three transactions $T_1$, $T_2$, $T_3$ and the oeprations sequence is given below: $T_1$: $Read$ $A$; $T_2$: $Write$ $A$; $T_3$: $Read$ $A$; $T_1$: $Write$ $A$; $T_3$: $Write$ $A$ and all the above transactions ... Is the above schedule is serializable or not? If yes it is equivalent to which serial schedule. Find the proper combination of the given alternatives from I to VII
asked Jan 16, 2019 in Databases `JEET 646 views
1 vote
1 answer
7
T1 T2 T3 R(X) W(X) commit W(X) commit R(X) commit is this transaction conflict serializable and view serializable?
asked Nov 18, 2018 in Databases aditi19 1k views
0 votes
1 answer
8
T1 T2 T3 W(Y) commit R(X) R(Y) W(Z) commit W(X) commit is this schedule a strict schedule?
asked Nov 18, 2018 in Databases aditi19 214 views
1 vote
1 answer
9
Tl:W(X), T2:R(X), Tl:W(X), T2:Commit, Tl:Abort is this schedule conflict serializable?
asked Nov 17, 2018 in Databases aditi19 432 views
2 votes
1 answer
10
Tl:R(X), T1:R(Y), T1:W(X), T2:R(Y), T3:W(Y), Tl:W(X), T2:R(Y) is this schedule view serializable?
asked Nov 16, 2018 in Databases aditi19 223 views
0 votes
0 answers
11
https://gateoverflow.in/1484/gate1999-2-6 in this questions after T2 is not granted exclusive lock on A does the transaction T2 gets blocked entirely or it can continue to acquire exclusive lock on B? and if T2 continues to acquire lock on B followed by T1 requesting for read and write lock on B successively, is it deadlock situation here? And is that why it is not 2PL?
asked Nov 11, 2018 in Databases aditi19 162 views
8 votes
1 answer
13
I am looking for some clarity on this topic. Here is some random schedule as an example: $r1(x) w1(x) r2(x) w2(x) r3(y) r3(x) w3(x) c3 a1 c2$ I was told, that for conflict serializablity we simply ignore the aborted transaction, ... not ignored for recoverability, strictness or avoidance of cascading rollbacks. I would be grateful if the question would be answered since this really confuses me.
asked May 28, 2018 in Databases flow2539 1.2k views
2 votes
0 answers
14
S1: R(A) W(A) W(B) S2: R(A) W(A) R(B) W(B) How many view serializable schedules are possible which are not conflict serializable? (A) 0 (B) 1 (C) 2 (D) 3
asked Jan 31, 2018 in Databases yolorn123 194 views
2 votes
0 answers
15
Which of the following statement is true? 1. time stamp protocol may not result recoverable schedule 2. in 2PL, No data are affected until all locks are obtained i.e., until the transaction is in its locked point. a) only a b) only b c) a and b d) none
asked Jan 18, 2018 in Databases hacker16 470 views
0 votes
1 answer
18
3 votes
1 answer
19
Consider the following schedule: S:R2(A) W1(B) W1(C) R3(B) R2(B) R1(A) C1 R2(C) C2 W3(A)C3 Please explain how it is allowed in 2 PL
asked Dec 6, 2017 in Databases shivangi5 499 views
1 vote
1 answer
20
If total n! serial schedules are possible , will all of them give the same result?
asked Sep 21, 2017 in Databases Parshu gate 93 views
2 votes
2 answers
21
State True or False and Tell reason 1) 2PL is always conflict serializable 2)Timestamp protocol is conflict and view serializable
asked Sep 16, 2017 in Databases srestha 1.3k views
1 vote
1 answer
22
Why is cascading rollback possible in 2 phase locking protocol, we know it guarantee serializability and serializable schedule are strict, which implies it is cascadeless? Please clear the doubt and correct me.
asked Sep 7, 2017 in Databases Kushagra Gusain 569 views
4 votes
0 answers
23
Consider the following transactions T1:r1(A) w1(A) r1(B) w1(B) T2:r2(B) w2(B) r2(A) w2(A) 1) How many schedules serializable as T1->T2 2) How many schedules serializable as T2->T1
asked Aug 2, 2017 in Databases Anshul Shankar 556 views
3 votes
2 answers
24
Draw the polygraph and explain whether it is view-serializable or not?
asked Jul 24, 2017 in Databases shashank023 188 views
0 votes
1 answer
25
In some part, it is given we cannot decide, why we cannot decide view serializability and recoverability? And, explain the solution for 7th part.
asked Jun 21, 2017 in Databases prasoon raghav 102 views
1 vote
1 answer
26
What is the difference between Phantom read Problem and Unrepeatable read problem?
asked Apr 2, 2017 in Databases Shubhanshu 94 views
0 votes
0 answers
27
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