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Recent questions tagged transactions

3 votes
2 answers
1
Can someone please explain the steps to check view serializability using polygraph method ? I am really having trouble in understanding it.
asked Jun 22, 2016 in Databases Aakash Das 577 views
11 votes
4 answers
2
What is the equivalent serial schedule for the following transactions? $T_1 - T_2 - T_3$ $T_3 - T_1 - T_2$ $T_2 - T_1 - T_3$ $T_1 - T_3 - T_2$
asked Jun 21, 2016 in Databases jothee 3k views
5 votes
3 answers
3
Which of the following is correct with respect to Two phase commit protocol? Ensures serializability Prevents Deadlock Detects Deadlock Recover from Deadlock
asked Jun 10, 2016 in Databases jothee 4.4k views
1 vote
1 answer
4
Read(Q) Write(Q) Write(Q) Is this schedule View serializable???? in <T1,T2> it violates the final Write criteria in <T2,T1> does it violate initial Read criteria?
asked May 15, 2016 in Databases namanom1 348 views
5 votes
3 answers
5
Which of the following is the highest isolation level in transaction management? Serializable Repeated Read Committed Read Uncommitted Read
asked Apr 26, 2016 in Databases makhdoom ghaya 4.2k views
41 votes
4 answers
6
Consider the following two phase locking protocol. Suppose a transaction $T$ accesses (for read or write operations), a certain set of objects $\{O_1,\ldots,O_k \}$ ... and deadlock-freedom guarantee neither serializability nor deadlock-freedom guarantee serializability but not deadlock-freedom guarantee deadlock-freedom but not serializability.
asked Feb 12, 2016 in Databases Sandeep Singh 11.7k views
20 votes
2 answers
7
Which one of the following is NOT a part of the ACID properties of database transactions? Atomicity Consistency Isolation Deadlock-freedom
asked Feb 12, 2016 in Databases Sandeep Singh 6.3k views
51 votes
6 answers
8
Consider the following database schedule with two transactions $T_{1}$ and $T_{2}$. $S= r_{2}\left(X\right); r_{1}\left(X\right); r_{2} \left(Y\right); w_{1} \left(X\right); r_{1} \left(Y\right); w_{2} \left(X\right); a_{1}; a_{2}$ ... the above schedule is TRUE? $S$ is non-recoverable. $S$ is recoverable, but has a cascading abort. $S$ does not have a cascading abort. $S$ is strict.
asked Feb 12, 2016 in Databases Akash Kanase 9.8k views
29 votes
6 answers
9
Suppose a database schedule $S$ involves transactions $T_1,........,T_n$ . Construct the precedence graph of $S$ with vertices representing the transactions and edges representing the conflicts.If $S$ is serializable, which one of the following ... is guaranteed to yield a serial schedule? Topological order Depth-first order Breadth- first order Ascending order of the transaction indices
asked Feb 12, 2016 in Databases Akash Kanase 6.8k views
0 votes
2 answers
10
S: T1(A)R2(B)W2(B)R2(A)W2(B)W1(A)R3(B)W3(B) Given schedule is view serializable ?
asked Feb 1, 2016 in Databases Bishnu Agrawal 400 views
2 votes
1 answer
11
schedule R(A) R(B) R(B) W(A) COMMIT R(C) R(B) W(C) W(B) R(A) R(C) COMMIT COMMIT The above scedule is -: a)conflict serializable b)recoverable c)cascadeless d)all of these according to me a)&b) answer given -:a)
asked Jan 31, 2016 in Databases sourav. 372 views
1 vote
1 answer
12
Consider the following two transactions. T1: R(A) W(A) R(B) W(B) T2: R(A) W(A) R(B) W(B) How many interleavings of these transactions are conflict serializable?
asked Jan 27, 2016 in Databases nikhil telkunte 340 views
1 vote
1 answer
13
I want to confirm my answers.. For 19.2.1 a) VIEW equal serial order T1 T2T3 or T2T1T3 b) VIEW equal serial order 6 possible orders c) 2 VIEW equal serial orders d) 2 VIEW equal serial orders For 19.2.2 A) 2 VIEW equal serial orders and one conflict equal one b) 1 VIEW equal serial orders and 1 conflict equal.. { all schedules have 1 conflict equal serial order} Plz point out my mistakes.
asked Jan 22, 2016 in Databases khushtak 326 views
5 votes
3 answers
15
how many view equivalent serial schedules are possible for the given schedule s: w1(a) r2(a) w3(a) r4(a) w5(a) r6(a) a) 2 b) 3 c) 6 d) 8
asked Jan 15, 2016 in Databases daksh 3.7k views
5 votes
1 answer
16
Is it Conservative 2 Phase locking (C2PL) ? T1 LOCK-X (A) LOCK-S (B) R(A) R(B) W(A) UNLOCK (A) COMMIT UNLOCK (B)
asked Jan 10, 2016 in Databases Shashank Chavan 892 views
3 votes
4 answers
17
6 votes
1 answer
18
Consider the following Two Transactions. How many Cascadeless schedules are possible over $T1$ & $T2$ ? $32$ $42$ $51$ $52$
asked Dec 23, 2015 in Databases Himanshu1 872 views
16 votes
1 answer
19
Consider the following Two Transactions. A) How many recoverable schedules can be formed over $T_{1}$ & $T_{2}$ ? $51$ $52$ $55$ $56$ B) How many cascadeless recoverable schedules can be formed over $T_{1}$ & $T_{2}$ ? $41$ $42$ $45$ $50$
asked Dec 21, 2015 in Databases nilamd 2.3k views
5 votes
2 answers
20
t1 t2 w(x) r(x) w(x) commit commit Why is this not view serializable?
asked Nov 14, 2015 in Databases divya_theodore 899 views
5 votes
1 answer
21
The transactions $T1$ and $T2$ are given as follows: $T1$: $R1(A)$ $W1(A)$ $R1(B)$ $W1(B)$ $T2$ : $R2(B)$ $W2(B)$ $R2(C)$ $W2(C)$ The total number of conflicts serializable that can be formed by $T1$ and $T2$ are Answer :20 (incorrect) The correct answer is 14
asked Oct 20, 2015 in Databases radha gogia 1.6k views
1 vote
1 answer
22
asked Oct 11, 2015 in Databases Shefali 3k views
4 votes
2 answers
23
$\begin{bmatrix} T1 &T2 \\ R(A) & \\ W(A)& \\ & R(A)\\ & W(A)\\ &R(B) \\ &W(B) \\ & Commit\\ Abort& \end{bmatrix}$ How is this schedule allowed in 2PL ? In 2PL , there must be a growing phase in , which is not present in T2 ..? This example is given in the book by Raghu Ramkrishnan on page 529 and 552 (for reference)
asked Oct 8, 2015 in Databases learncp 1.4k views
2 votes
2 answers
24
According to 2-phase locking protocol, if a transaction acquires an exclusive lock on any object, another transaction cannot obtain any kind of lock on it till the first transaction unlocks it. Is the reverse also true, i.,e., if a transaction acquires a shared ... interleaving transaction cannot acquire any kind of lock on it..? or it cannot acquire exclusive lock, but can acquire shared lock. ?
asked Sep 29, 2015 in Databases learncp 1.9k views
0 votes
3 answers
25
Suppose we have a schedule containing two transactions  as shown- $\begin{bmatrix} T1 & T2 \\ R(A) & \\ W(A) & \\ & R(A) \\  & W(A) \\ R(B)& \\ W(B)& \\ & R(B) \\  & W(B) \end{bmatrix}$   We will proceed to create the polygraph for the ... schedule. If we create separate polygraphs, for A we will get t1->t2, and for B we will get t1->t2.. Same graph will be obtained if we draw a single polygraph
asked Sep 19, 2015 in Databases learncp 1k views
5 votes
1 answer
26
I am unable to differentiate between a strict schedule and a cascadeless schedule...although what I have understood is that in strict schedule, we cannot perform read/write till the other transaction commits..but isnt this condition also valid for cascadeless schedules ? Can someone please explain by giving an example.
asked Sep 18, 2015 in Databases learncp 7.4k views
45 votes
5 answers
27
Consider the partial Schedule $S$ involving two transactions $T1$ and $T2$. Only the $\textit{read}$ and the $\textit{write}$ operations have been shown. The $\textit{read}$ operation on data item $P$ is denoted by $\textit{read(P)}$ and ... aborted and then re-started to ensure transaction atomicity Schedule $S$ is recoverable and can ensure transaction atomicity and nothing else needs to be done
asked Feb 15, 2015 in Databases jothee 6.5k views
41 votes
4 answers
28
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); ... the redo list? Undo: T3, T1; Redo: T2 Undo: T3, T1; Redo: T2, T4 Undo: none; Redo: T2, T4, T3, T1 Undo: T3, T1, T4; Redo: T2
asked Feb 13, 2015 in Databases jothee 12k views
29 votes
4 answers
29
Consider the following transaction involving two bank accounts $x$ and $y$. read(x); x:=x-50; write (x); read(y); y:=y+50; write(y) The constraint that the sum of the accounts $x$ and $y$ should remain constant is that of Atomicity Consistency Isolation Durability
asked Feb 12, 2015 in Databases jothee 5.3k views
4 votes
3 answers
30
Consider $3$ transactions $T_1, T_2$ and $T_3$ having $2, 3$ and $4$ operations respectively. Find the number of concurrent schedules?
asked Jan 29, 2015 in Databases Vikrant Singh 6.7k views
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