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Recent questions tagged transactions

1 vote
2 answers
1
Assume transaction $A$ holds a shared lock $R.$ If transaction $B$ also requests for a shared lock on $R.$ It will result in deadlock situation immediately be granted immediately be rejected be granted as soon as it is released by $A$
asked Apr 1, 2020 in Databases Lakshman Patel RJIT 359 views
0 votes
1 answer
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When transaction $Ti$ requests a data item currently held by $Tj,Ti$ is allowed to wait only if it has a time stamp smaller than that of $Tj$ (that is $Ti$ is order than Tj). Otherwise, $Ti$ is rolled back (dies). This is Wait-die Wait-wound Wound-wait Wait
asked Apr 1, 2020 in Databases Lakshman Patel RJIT 271 views
0 votes
3 answers
3
When transaction $Ti$ requests a data item currently held by $Tj,Ti$ is allowed to wait only if it has a timestamp smaller than that of $Tj$ (that is $Ti$ is order than Tj). Otherwise, $Ti$ is rolled back (dies). This is Wait-die Wait-wound Wound-wait Wait
asked Apr 1, 2020 in Databases Lakshman Patel RJIT 324 views
0 votes
1 answer
4
Assume transaction $A$ holds a shared lock $R.$ If transaction $B$ also requests for a shared lock on $R.$ It will result in deadlock situation immediately be granted immediately be rejected be granted as soon as it is released by $A$
asked Apr 1, 2020 in Databases Lakshman Patel RJIT 195 views
1 vote
3 answers
5
In conservative two phase locking protocol, a transaction Should release all the locks only at the beginning of transaction Should release exclusive locks only after the commit operation Should acquire all the exclusive locks at the beginning of transaction Should acquire all the locks at the beginning of transaction
asked Mar 30, 2020 in Databases Lakshman Patel RJIT 827 views
1 vote
4 answers
6
Consider following schedules involving two transactions: $S_{1}: \: r_{1}(X);r_{1}(Y);r_{2}(X);r_{2}(Y);w_{2}(Y);w_{1}(X)$ $S_{2}: \: r_{1}(X);r_{2}(X);r_{2}(Y);w_{2}(Y);r_{1}(Y);w_{1}(X)$ Which of the ... . $S_1$ is conflict serializable and $S_2$ is not conflict serializable $S_1$ is not conflict serializable and $S_2$ is conflict serializable Both $S_1$ and $S_2$ are not conflict serializable
asked Mar 24, 2020 in Databases jothee 1.1k views
1 vote
1 answer
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0 votes
1 answer
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During its execution, a transaction passes through several states, until it finally commits or aborts. List all possible sequences of states through which a transaction may pass. Explain why each state transition may occur.
asked Apr 1, 2019 in Databases akash.dinkar12 377 views
0 votes
0 answers
10
Database-system implementers have paid much more attention to the ACID properties than have file-system implementers. Why might this be the case ?
asked Apr 1, 2019 in Databases akash.dinkar12 459 views
0 votes
0 answers
11
Consider a file system such as the one on your favorite operating system. a. What are the steps involved in creation and deletion of files, and in writing data to a file ? b. Explain how the issues of atomicity and durability are relevant to the creation and deletion of files, and to writing data to files.
asked Apr 1, 2019 in Databases akash.dinkar12 165 views
0 votes
0 answers
12
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0 votes
1 answer
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How can 2PL protocol ( simple one ) ensure conflict serializability even though it cannot ensure freedom from deadlock ? I mean ,if a schedule is conflict serializable it has a conflict equivalent to a serial schedule and serial schedules won't have deadlocks .Right ?
asked Mar 30, 2019 in Databases ashunimbz 207 views
0 votes
2 answers
15
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 308 views
20 votes
4 answers
16
Consider the following two statements about database transaction schedules: Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable. Timestamp-ordering concurrency control protocol with Thomas' Write Rule can generate view serializable schedules that are not ... Which of the above statements is/are TRUE? I only II only Both I and II Neither I nor II
asked Feb 7, 2019 in Databases Arjun 8.9k views
1 vote
2 answers
17
T1 LOCK-X (A) LOCK-S (B) R(A) R(B) W(A) UNLOCK (A) COMMIT UNLOCK (B) is this following CONSERVATIVE 2PL ? doubt : in conservative locking schme ..all locks are aqured before starting but locks can be released at ANY time ..so conservative need not be strict/rigorous OR is it only after commit ??
asked Jan 25, 2019 in Databases jatin khachane 1 497 views
4 votes
3 answers
18
Consider the following schedule $\text{S : r2(A), w1(B), w1(C), R3(B), r2(B), r1(A), commit_1, r2(C), commit_2, w3(A), commit_3 }$ Consider the following statements : S1 : Schedule(S) is conflict serializable schedule. S2 : Schedule(S) is allowed by 2PL. S3 : Schedule(S) is strict recoverable schedule. S4 : Schedule(S) is allowed by strict 2PL. How many above statements true about schedule(S) ?
asked Jan 20, 2019 in Databases Mk Utkarsh 1.3k views
2 votes
3 answers
19
how many view equivalent schedules are possible for the Sch given below:
asked Jan 18, 2019 in Databases Nandkishor3939 869 views
1 vote
0 answers
20
Is different 2 phase locking a subset of each other? For example, if the schedule is Strict 2PL then it will also be simple 2PL. Something like a 2PL is a subset of Strict 2PL is a subset of rigorous 2PL.
asked Jan 18, 2019 in Databases vinay chauhan 163 views
0 votes
1 answer
21
Is the following schedule conflict serializable T1 T2 T3 W(X) commit R(X) W(X) R(X) W(X) commit W(X) commit
asked Jan 16, 2019 in Databases jatin khachane 1 421 views
0 votes
1 answer
22
Q50. how many statements is true unrepeatable read also know as read write conflict Strict 2PL may have read write conflict 1st one given as true now my doubt is we know that read write conflict that is https://www.revolvy.com/page/Read%E2%80%93write-conflict and we also ... watch?v=mLNfpqybSZM . how we can call unrepeatable read as read write conflict 2nd one given as false but i think it is true
asked Jan 16, 2019 in Databases Gurdeep Saini 231 views
1 vote
0 answers
23
Which of the following time stamp ordering protocol(s) allow the following schedules? $T:W_1(A)\ W_2(A)\ W_3(A)\ R_2(A)\ R_4(A)$ Time stamps: $T_1=5,T_2=10,T_3=15,T_4=20$ Thomas write rule Multiversion time stamp protocol Basic Time stamp All of these
asked Jan 13, 2019 in Databases Gupta731 173 views
1 vote
1 answer
24
Consider following Schedule S with data item x : S : W1(X) R2(X) W3(X) R4(X) W5(X) R6(X) W7(X) R8(X) W9(X) R10(X) The number of schedule view equivalent to Schedule S but not conflict equivalent to Schedule S ?
asked Jan 13, 2019 in Databases Na462 539 views
0 votes
2 answers
25
Why having a Blind Write may help a schedule(which is not conflict serializable) to be view serializable ? I can see check the condition and verify this. but i don’t understand the concept, i hope i am able to frame my question properly. I read books but my doubt is still there. Please help me out guys. Thanks
asked Jan 10, 2019 in Databases Aakash_ 348 views
0 votes
1 answer
26
In crash recovery in the checkpoint mechanism. Till the last checkpoint for all committed transactions redo will be done and all uncommited transactions undo is done. Can anyone explain what is the reason behind it ?
asked Jan 9, 2019 in Databases amitqy 165 views
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