Recent questions tagged transaction-and-concurrency / GATE Overflow for GATE CSE

What is a cascadeless schedule ? Why is cascadelessness of schedules desirable ? Are there any circumstances under which it would be desirable to allow noncascadeless sch...

akash.dinkar12

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akash.dinkar12 asked Apr 1, 2019

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124

DBMS Korth Edition 4 Exercise 15 Question 11 (Page No. 589)
What is a recoverable schedule ? Why is recoverability of schedules desirable? Are there any circumstances under which it would be desirable to allow nonrecoverable schedules ? Explain your answer.

What is a recoverable schedule ? Why is recoverability of schedules desirable? Are there any circumstances under which it would be desirable to allow nonrecoverable sched...

akash.dinkar12

294 views

akash.dinkar12 asked Apr 1, 2019

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0 answers

125

DBMS Korth Edition 4 Exercise 15 Question 10 (Page No. 589)
Consider the precedence graph of Figure 15.18. Is the corresponding schedule conflict serializable ? Explain your answer.

Consider the precedence graph of Figure 15.18. Is the corresponding schedule conflict serializable ? Explain your answer.

akash.dinkar12

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akash.dinkar12 asked Apr 1, 2019

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126

DBMS Korth Edition 4 Exercise 15 Question 9 (Page No. 589)
Since every conflict-serializable schedule is view serializable, why do we emphasize conflict serializability rather than view serializability?

Since every conflict-serializable schedule is view serializable, why do we emphasize conflict serializability rather than view serializability?

akash.dinkar12

832 views

akash.dinkar12 asked Apr 1, 2019

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127

DBMS Korth Edition 4 Exercise 15 Question 8 (Page No. 589)
Consider the following two transactions: $T_1:$ $read(A);$ $read(B);$ $if A = 0$ $then$ $B := B + 1;$ $write(B);$ $T_2:$ $read(B);$ $read(A);$ $if B = 0$ $then$ $A := A + 1;$ ... $T_1$ and $T_2$ that produces a nonserializable schedule. $c$. Is there a concurrent execution of $T_1$ and $T_2$ that produces a serializable schedule ?

Consider the following two transactions:$T_1:$ $read(A);$ $read(B);$ $if A = 0$ $then$ $B := B + 1;$ $write(B);$$T_2:$ $read(B);$ ...

akash.dinkar12

339 views

akash.dinkar12 asked Apr 1, 2019

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0 answers

128

DBMS Korth Edition 4 Exercise 15 Question 7 (Page No. 589)
Explain the distinction between the terms $serial$ schedule and $serializable$ schedule.

Explain the distinction between the terms $serial$ schedule and $serializable$ schedule.

akash.dinkar12

191 views

akash.dinkar12 asked Apr 1, 2019

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0 answers

129

DBMS Korth Edition 4 Exercise 15 Question 6 (Page No. 589)
Justify the following statement: Concurrent execution of transactions is more important when data must be fetched from (slow) disk or when transactions are long, and is less important when data is in memory and transactions are very short.

Justify the following statement: Concurrent execution of transactions is more important when data must be fetched from (slow) disk or when transactions are long, and is l...

akash.dinkar12

732 views

akash.dinkar12 asked Apr 1, 2019

0 votes

1 answer

130

DBMS Korth Edition 4 Exercise 15 Question 5 (Page No. 588)
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.

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 m...

akash.dinkar12

2.6k views

akash.dinkar12 asked Apr 1, 2019

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131

DBMS Korth Edition 4 Exercise 15 Question 4 (Page No. 588)
Database-system implementers have paid much more attention to the ACID properties than have file-system implementers. Why might this be the case ?

Database-system implementers have paid much more attention to the ACID properties than have file-system implementers. Why might this be the case ?

akash.dinkar12

867 views

akash.dinkar12 asked Apr 1, 2019

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0 answers

132

DBMS Korth Edition 4 Exercise 15 Question 3 (Page No. 588)
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.

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 ?...

akash.dinkar12

420 views

akash.dinkar12 asked Apr 1, 2019

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0 answers

133

DBMS Korth Edition 4 Exercise 15 Question 2 (Page No. 588)
Suppose that there is a database system that never fails. Is a recovery manager required for this system ?

Suppose that there is a database system that never fails. Is a recovery manager required for this system ?

akash.dinkar12

351 views

akash.dinkar12 asked Apr 1, 2019

0 votes

1 answer

134

DBMS Korth Edition 4 Exercise 15 Question 1 (Page No. 588)
List the $ACID$ properties. Explain the usefulness of each.

List the $ACID$ properties. Explain the usefulness of each.

akash.dinkar12

297 views

akash.dinkar12 asked Apr 1, 2019

0 votes

2 answers

135

Self doubt on 2PL protocol
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 ?

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...

ashunimbz

582 views

ashunimbz asked Mar 30, 2019

0 votes

2 answers

136

Gate Previous Year Question-2009
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?

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 serializabl...

debasree88

895 views

debasree88 asked Feb 24, 2019

29 votes

5 answers

137

GATE CSE 2019 | Question: 11
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

Consider the following two statements about database transaction schedules:Strict two-phase locking protocol generates conflict serializable schedules that are also recov...

Arjun

17.5k views

Arjun asked Feb 7, 2019

1 votes

2 answers

138

Transactions
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 ??

T1LOCK-X (A)LOCK-S (B)R(A)R(B)W(A)UNLOCK (A)COMMITUNLOCK (B)is this following CONSERVATIVE 2PL ? doubt : in conservative locking schme ..all locks are aqured before start...

jatin khachane 1

1.4k views

jatin khachane 1 asked Jan 25, 2019

5 votes

3 answers

139

MadeEasy Test Series 2019: Databases - Transaction And Concurrency
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 ... ) is strict recoverable schedule. S4 : Schedule(S) is allowed by strict 2PL. How many above statements true about schedule(S) ?

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 :...

Mk Utkarsh

3.3k views

Mk Utkarsh asked Jan 20, 2019

3 votes

4 answers

140

No. of View equivalent schedules
how many view equivalent schedules are possible for the Sch given below:

how many view equivalent schedules are possible for the Sch given below:

Nandkishor3939

2.3k views

Nandkishor3939 asked Jan 18, 2019

2 votes

0 answers

141

Self doubt, 2PL
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.

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...

vinay chauhan

600 views

vinay chauhan asked Jan 18, 2019

0 votes

1 answer

142

Self Doubt
Is the following schedule conflict serializable T1 T2 T3 W(X) commit R(X) W(X) R(X) W(X) commit W(X) commit

Is the following schedule conflict serializableT1T2T3W(X) commit R(X) W(X) R(X) W(X) commit W(X) commit

jatin khachane 1

1.4k views

jatin khachane 1 asked Jan 16, 2019

1 votes

1 answer

143

Applied Course | Mock GATE | Test 1 | Question: 59
Consider the following interleaved schedule with two transactions T1 and T2. The Two-Phase Locking Protocol is followed for achieving concurrency control. Which of the following statements is true with respect to the given schedule? The ... ; T2 The schedule results in a deadlock The schedule is not permitted as per Two Phase Locking Protocol

Consider the following interleaved schedule with two transactions T1 and T2. The Two-Phase Locking Protocol is followed for achieving concurrency control. Which of the fo...

Applied Course

996 views

Applied Course asked Jan 16, 2019

0 votes

1 answer

144

MadeEasy Full Length Test 2018: Databases - Transactions
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/ ... . how we can call unrepeatable read as read write conflict 2nd one given as false but i think it is true

Q50. how many statements is trueunrepeatable read also know as read write conflictStrict 2PL may have read write conflict 1st one given as true now my doubt is we know th...

Gurdeep Saini

594 views

Gurdeep Saini asked Jan 16, 2019

1 votes

0 answers

145

Gateforum Test Series: Databases - Transactions
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

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: $T_1=5,T_2=10,T_3=15,T_4=20$Th...

Gupta731

512 views

Gupta731 asked Jan 13, 2019

1 votes

1 answer

146

View Serializability
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 ?

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 n...

Na462

1.5k views

Na462 asked Jan 13, 2019

0 votes

2 answers

147

Self Doubt Blind Write
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

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 und...

Aakash_

1.5k views

Aakash_ asked Jan 10, 2019

1 votes

1 answer

148

Self Doubt
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 ?

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...

amitqy

597 views

amitqy asked Jan 9, 2019

1 votes

2 answers

149

Ace Test Series: DBMS - Transaction And Serializable

Kaushal Sanadhya

620 views

Kaushal Sanadhya asked Jan 9, 2019

0 votes

0 answers

150

Number of conflict serial orderings (with commit) Applied Course FT-1
Consider the following order of transactions: T2: R(y); T3:W(y); T3: commit; T1: W(y); T1: commit; T2: R(x); T2: W(z); T2: commit; T4: R(y);T4: R(x); T4: commit. Let the above schedule be S, if S is serializable, then how many conflict serial orderings of S is possible?___________

Consider the following order of transactions:T2: R(y); T3:W(y); T3: commit; T1: W(y); T1: commit; T2: R(x); T2: W(z); T2: commit; T4: R(y);T4: R(x); T4: commit.Let the ab...

Mk Utkarsh

1.9k views

Mk Utkarsh asked Jan 8, 2019

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