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Recent questions tagged transactions
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Tga test series
Why dirty read ? Here T2 was commited after the T1....what about the option c?
asked
Feb 5
in
Databases
by
Enolx.21
(
49
points)
|
11
views
transactions
test-series
selfdoubt
0
votes
0
answers
Self Doubt , Databases
Is Read – Write conflict possible in a strict recoverable schedule? As strict 2PL guarantees strict recoverable. Is Read-Write conflict possible in a strict recoverable schedule ?
asked
Jan 24
in
Databases
by
anurags228
(
23
points)
|
8
views
transactions
databases
0
votes
0
answers
Cascade Rollback and Not recoverable at the same time
asked
Jan 18
in
Databases
by
reboot
(
5
points)
|
9
views
selfdoubt
databases
transactions
0
votes
0
answers
Databases: recoverability
Assume $S$ is a schedule that has both read and write oeration with different transaction with different data variable. Also assume all the operations are atomic in nature. Which of the following is true? $S$ with no dirty read then $S$ is cascadeless ... own set of data variables. If so then there is no lost update, no cascading rollback and so it is strict recoverable.
asked
Dec 24, 2020
in
Databases
by
ytheuyr
(
2
points)
|
5
views
databases
transactions
0
votes
0
answers
no of rollback for failed transactions
(Say) transactions data dependency(dirty read) are in the order T1→ T2 → T3 → …..Tn ( Here A→ B means A write and B read). So after Tn read if T1 failed then what should be the no. of transactions need to rollback Are we also need to include failed(T1) transaction in no. of transaction need to be rolled back? what should be the answer n or (n-1)?
asked
Dec 19, 2020
in
Databases
by
wander
(
301
points)
|
12
views
transactions
0
votes
0
answers
Serialisability in Blind write
I read one Gate question and in Korth's book that if a schedule contains blind write then it is not conflict serialisable. I am not able to understand the reason. This is the gate question – https://gateoverflow.in/302837/gate2019-11 I also read that timestamp protocol allows conflict serializable schedules.
asked
Oct 12, 2020
in
Databases
by
vizzard110
(
85
points)
|
12
views
selfdoubt
transactions
0
votes
0
answers
Self Doubt on Transcation & Concurrency Control
Why this schedule is not View Serializable?? Anyone please elaborate this.
asked
Sep 7, 2020
in
Databases
by
AbhayPrajapati
(
7
points)
|
41
views
view-serializablity
databases
transactions
selfdoubt
0
votes
1
answer
Raghu Ramkrishnan - Transactions and Concurrency Control
asked
Aug 30, 2020
in
Databases
by
pritishc
(
27
points)
|
74
views
databases
transactions
view-serializablity
timestamp-ordering
0
votes
2
answers
Self doubt DBMS Conflict Equivalent schedules
$\text{Consider the transactions given below}$ What are the number of conflict equivalent schedules possible What is the approach to solve such questions T1 T2 T3 $r_{A}$ $w_{B}$ $r_{A}$ $w_{B}$ $r_{A}$ $w_{B}$
asked
Aug 26, 2020
in
Databases
by
ijnuhb
(
741
points)
|
44
views
conflict-equivalent
databases
equivalence-relation
transactions
conflict
0
votes
1
answer
Serializability
Are all serializable schedules recoverable, cascade-less, strict???
asked
Aug 4, 2020
in
Databases
by
manas_kulkarni
(
1
point)
|
31
views
databases
transactions
ace-academy-test-series
0
votes
0
answers
Conflict Equivalence-Databases (Self doubt)
consider statement 1 : Two schedules are conflict equivalent when the precedence graphs are isomorphic. Is this statement correct or wrong. It is the counter example for the same S1: = R1(A) R2(A)W1(A) W2(A) S2: = R1(A) ... present in both schedules ( say T1 and T2) must be same.Is this also the condition for checking Conflict Equivalency check?
asked
Jul 9, 2020
in
Databases
by
prajjwalsingh_11
(
15
points)
|
7
views
databases
conflict-equivalent
conflict
equivalence-relation
transactions
0
votes
0
answers
deadlock in databases
my question is isn’t wait wound and wait die deadlock prevention algo so how can we say that they are deadlock avoidance and how they can cause more aborts than needed?
asked
Jun 25, 2020
in
Databases
by
abcd9982
(
87
points)
|
21
views
databases
made-easy-test-series
transactions
deadlock-in-databases
0
votes
1
answer
GATE2017-2-44 Video Solution
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 ... 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 ______
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
24
views
gate2017-2
databases
transactions
numerical-answers
conflict-serializable
video-solution
0
votes
1
answer
GATE2006-20, ISRO2015-17 Video Solution
Consider the following log sequence of two transactions on a bank account, with initial balance $12000,$ that transfer $2000$ to a mortgage payment and then apply a $5\%$ interest. T1 start T1 B old $=1200$ new $=10000$ T1 ... $2$ and $3$ because transaction T1 has committed We can apply redo and undo operations in arbitrary order because they are idempotent
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
12
views
gate2006
databases
transactions
normal
isro2015
video-solution
0
votes
0
answers
GATE2010-20 Video Solution
Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? 2-phase locking Time-stamp ordering I only II only Both I and II Neither I nor II
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
4
views
gate2010
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2015-2-46 Video Solution
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, ... 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
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
14
views
gate2015-2
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2016-1-51 Video Solution
Consider the following two phase locking protocol. Suppose a transaction $T$ accesses (for read or write operations), a certain set of objects $\{O_1,\ldots,O_k \}$. This is done in the following ... -freedom guarantee neither serializability nor deadlock-freedom guarantee serializability but not deadlock-freedom guarantee deadlock-freedom but not serializability.
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
9
views
gate2016-1
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2016-2-51 Video Solution
Consider the following database schedule with two transactions $T_{1}$ and $T_{2}$ ... 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
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
17
views
gate2016-2
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2012-27 Video Solution
Consider the following transactions with data items $P$ and $Q$ initialized to zero: ${\begin{array}{|c|l|r|c|}\hline \textbf{$ ... leads to a serializable schedule a schedule that is not conflict serializable a conflict serializable schedule a schedule for which a precedence graph cannot be drawn
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
15
views
gate2012
databases
transactions
normal
video-solution
0
votes
1
answer
GATE2014-2-29 Video Solution
Consider the following schedule S of transactions $T1, T2, T3, T4:$ ... recoverable S is not conflict-serializable but is recoverable S is both conflict-serializable and recoverable S is neither conflict-serializable not is it recoverable
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
12
views
gate2014-2
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2016-2-22 Video Solution
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 ... guaranteed to yield a serial schedule? Topological order Depth-first order Breadth- first order Ascending order of the transaction indices
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
6
views
gate2016-2
databases
transactions
normal
video-solution
0
votes
1
answer
GATE1999-2.6 Video Solution
For the schedule given below, which of the following is correct: ... schedule is not serializable but can occur in a scheme using 2PL protocol This schedule is not serializable and cannot occur in a scheme using 2PL protocol
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
9
views
gate1999
databases
transactions
normal
video-solution
0
votes
1
answer
GATE2007-IT-66 Video Solution
Consider the following two transactions : T1 and T2. T1 : read (A); T2 : read (B); read (B); read (A); if A = 0 then B ← B + 1; if B ≠ 0 then A ← A - 1; write (B); write (A); Which of the following schemes, using shared and exclusive locks, satisfy the ... ← B + 1; then A ← A - 1; write (B); write (A); unlock (A); unlock (A); unlock (B); unlock (B); commit; commit;
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
10
views
gate2007-it
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2003-29, ISRO2009-73 Video Solution
Which of the following scenarios may lead to an irrecoverable error in a database system? A transaction writes a data item after it is read by an uncommitted transaction A transaction reads a data item after it is read by an ... it is written by a committed transaction A transaction reads a data item after it is written by an uncommitted transaction
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
10
views
gate2003
databases
transactions
easy
isro2009
video-solution
0
votes
0
answers
GATE2015-3-29 Video Solution
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 $P$ ... re-started to ensure transaction atomicity Schedule $S$ is recoverable and can ensure transaction atomicity and nothing else needs to be done
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
9
views
gate2015-3
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2019-11 Video Solution
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 ... the above statements is/are TRUE? I only II only Both I and II Neither I nor II
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
9
views
gate2019
databases
transactions
video-solution
+1
vote
1
answer
GATE2008-IT-63 Video Solution
Consider the following three schedules of transactions T1, T2 and T3. [Notation: In the following NYO represents the action Y (R for read, W for write) performed by transaction N on object O.] ... equivalent to each other S2 is conflict equivalent to S3, but not to S1 S1 is conflict equivalent to S2, but not to S3
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
6
views
gate2008-it
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2004-IT-77 Video Solution
Consider the following schedule $S$ of transactions $T1$ and $T2:$ ... only as $T2, T1$ $S$ is serializable both as $T1, T2$ and $T2, T1$ $S$ is not serializable either as $T1,T2$ or as $T2,T1$
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
7
views
gate2004-it
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2015-2-1 Video Solution
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
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
14
views
gate2015-2
databases
transactions
easy
video-solution
0
votes
0
answers
GATE2010-42 Video Solution
Consider the following schedule for transactions $T1, T2$ and $T3:$ ... correct serialization of the above? $T1 \to T3 \to T2$ $T2 \to T1 \to T3$ $T2 \to T3 \to T1$ $T3 \to T1 \to T2$
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
6
views
gate2010
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2014-1-29 Video Solution
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? $r_1(x)$; $r_2(x)$; $w_1(x)$; $r_3(x)$; $w_2(x)$; $r_2(x)$ ... $r_1(x)$; $w_2(x)$; $w_1(x)$; $r_2(x)$; $w_2(x)$; $r_3(x)$; $r_1(x)$; $w_1(x)$;
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
6
views
gate2014-1
databases
transactions
normal
video-solution
+1
vote
1
answer
GATE2003-87 Video Solution
Consider three data items $D1, D2,$ and $D3,$ and the following execution schedule of transactions $T1, T2,$ and $T3.$ In the diagram, $R(D)$ and $W(D)$ denote the actions reading and writing the data item $D$ ... $T2; T1; T3$ The schedule is serializable as $T3; T2; T1$ The schedule is not serializable
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
8
views
gate2003
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2014-3-29 Video Solution
Consider the transactions $T1, T2, \:\text{and} \:T3$ and the schedules $S1 \:\text{and} \:S2$ given below. $T1: r1(X); r1(Z); w1(X); w1(Z) $ $T2: r2(Y); r2(Z); w2(Z) $ $T3: r3(Y); r3(X); w3(Y) $ ... ? Only $S1$ is conflict-serializable. Only $S2$ is conflict-serializable. Both $S1$ and $S2$ are conflict-serializable. Neither $S1$ nor $S2$ is conflict-serializable.
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
4
views
gate2014-3
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2007-64 Video Solution
Consider the following schedules involving two transactions. Which one of the following statements is TRUE? $S_1 :r_1(X); r_1(Y); r_2(X); r_2(Y); w_2(Y); w_1(X)$ $S_2 :r_1(X); r_2(X); r_2(Y); w_2(Y); r_1(Y); w_1(X)$ ... $S_1$ is not conflict serializable and $S_2$ is conflict serializable. Both $S_1$ and $S_2$ are not conflict serializable.
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
5
views
gate2007
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2016-1-22 Video Solution
Which one of the following is NOT a part of the ACID properties of database transactions? Atomicity Consistency Isolation Deadlock-freedom
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
5
views
gate2016-1
databases
transactions
easy
video-solution
0
votes
0
answers
GATE2009-43 Video Solution
Consider two transactions $T_1$ and $T_2$, and four schedules $S_1, S_2, S_3, S_4$, of $T_1$ and $T_2$ as given below: $T_1: R_1[x]W_1[x]W_1[y]$ $T_2: R_2[x]R_2[y]W_2[y]$ $S_1: R_1[x]R_2[x]R_2[y] W_1[x] W_1[y] W_2[y]$ ... $S_1 \text{ and } S_2$ $S_2 \text{ and } S_3$ $S_3$ only $S_4$ only
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
16
views
gate2009
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2005-IT-67 Video Solution
A company maintains records of sales made by its salespersons and pays them commission based on each individual's total sales made in a year. This data is maintained in a table with following schema: salesinfo = (salespersonid, ... running concurrently throughout Execute T3 followed by T2; T1 running concurrently throughout Execute T3 followed by T2 followed by T1
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
14
views
gate2005-it
databases
transactions
normal
video-solution
0
votes
0
answers
GATE2005-IT-24 Video Solution
Amongst the ACID properties of a transaction, the 'Durability' property requires that the changes made to the database by a successful transaction persist Except in case of an Operating System crash Except in case of a Disk crash Except in case of a power failure Always, even if there is a failure of any kind
asked
Apr 18, 2020
in
Databases
by
admin
(
573
points)
|
16
views
gate2005-it
databases
transactions
easy
video-solution
0
votes
0
answers
Made easy database management system page 31 ques 32
asked
Apr 15, 2020
in
Databases
by
Setika Mehra
(
13
points)
|
13
views
databases
er-diagram
sql
serializablity
transactions
0
votes
0
answers
Made easy database management system page 28 ques 13
asked
Apr 15, 2020
in
Databases
by
Setika Mehra
(
13
points)
|
17
views
serializablity
transactions
sql
databases
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