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Recent questions tagged 2phaselocking

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Subject : Databse Topic: 2pl locking protocol..... If the given schedule is allowed under any 2pl( basic 2pl,strict or rigorous) then it is also allowed in conflict serializble , so if the schedule which is allowed in conflict serializable then also we can say it will be allowed in 2pl?

Ashutosh_17 asked in Databases Mar 28

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concurrency control
question about concurrency control methods

jayadev asked in Databases Jul 3, 2022

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1 answer

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2 Phase Locking | Made Easy Test Series
Given Problem : S1 can be shown allowed under 2PL. However, the solution that they have provided for S2 : Seems wrong, as So, is S2 allowed under 2PL, or the answer given is incorrect?

palashbehra5 asked in Databases Jan 17, 2022

by palashbehra5

594 views

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2 answers

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2PL | Made Easy Full Syllabus Test
Given problem and solution. It is true that the given schedule is not serializable, what I don't understand is how it is not allowed by the 2PL protocol? Given Schedule : T1 T2 T3 R(A) R(A) R(B) W(B) W(A) R(A) Under 2PL : T1 T3 T3 S(A) R(A) S(A) R(A) S(B) R(B) X(B) W(B) Lock Point U(B) X(A) W(A) Lock Point U(A) S(A) Lock Point U(A)

palashbehra5 asked in Databases Jan 13, 2022

by palashbehra5

428 views

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1 answer

5

DBMS: SELF DOUBT .
Is basic 2 phase locking always recoverable?

Hirak asked in Databases Jun 10, 2019

by Hirak

480 views

2 votes

1 answer

6

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.

vinay chauhan asked in Databases Jan 18, 2019

by vinay chauhan

396 views

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GA Test series
pls explain why C is correct not A? isn’t every schedule that is supported by 2PL conflict serializable?

aditi19 asked in Databases Dec 8, 2018

248 views

1 vote

1 answer

8

2 Phase Locking
is it supported by 2PL?

aditi19 asked in Databases Dec 8, 2018

424 views

1 vote

1 answer

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2PL Doubt
T1: W(X), T2: R(Y), T1: R(Y), T2: R(X) does 2PL protocol allows it? T1 T2 L-X(X) W(X) L-S(Y) R(Y) U(X) L-S(Y) R(Y) L-S(X) R(X) here T2 is granted lock on X as T1 enters shrinking phase as no exclusive locks are held on X is my solution correct?

aditi19 asked in Databases Nov 25, 2018

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3 answers

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is conservative 2PL is recoverable
is conservative 2PL is recoverable schedule ?

Gurdeep Saini asked in Databases Nov 6, 2018

by Gurdeep Saini

3.0k views

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transaction and concurrency control protocol
Consider th following schedule r1(A)r2(B)r3(C)w1(B)w2(C)w3(D) Find the schedule which are possible to execute by strict 2PL protocol? consider commit operation as immediate last operation of each transaction

gatecrack asked in Databases Sep 5, 2018

328 views

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2pl protocol
Can someone explain how transactions can be serialized in order of their lock points (the point where the transactions acquire their final lock)?

Parimal Paritosh asked in Databases Sep 3, 2018

by Parimal Paritosh

369 views

1 vote

0 answers

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2PL Protocol
Consider the following schedules involving two transactions. Which of the following statements is true? A. Both S1 and S2 are allowed under 2PL. B. Only S2 is allowed under 2PL. C. Only S1 is allowed under 2PL. D. Neither S1 nor S2 allowed under 2PL.

Na462 asked in Databases Jul 14, 2018

by Na462

808 views

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Question on lock
Which of the following are correct statements? (i) It is possible for different transactions to hold locks on the same data item in x and z node at the same time. (ii) It is possible for more than one transaction to hold lock on same database element in 3 mode, at the same time another transaction ... (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (i), (ii) and (iii)

shubham6596 asked in Databases Jul 8, 2018

415 views

1 vote

0 answers

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2 PL with lock upgrade and Conflict serializability
Hi Guys, Please tell following statement is T/F --> If there is a schedule which is conflict serializable. But there may not exist any 2 PL with lock upgrade scheme to execute it. PS: ping @Krish__, @rahul sharma 5, @Red_devil, @Shivam Chauhan, @Tuhin Dutta, @Anu007, @Ashwin Kulkarni @reena_kandari and @srestha ji.

Chhotu asked in Databases Dec 26, 2017

by Chhotu

827 views

1 vote

1 answer

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DBMS: CONCURRENCY CONTROL 2 PHASE LOCKING PROTOCOL
T1: r1(x)w1(x)r1(y)w1(y) T2: r2(y)w2(y) L is xclusive lock and U is unlock L1(y)L1(X)R1(Y)W1(Y)R1(X)W1(X)U1(X)U1(Y)L2(Y)R2(Y)W2(Y)U2(Y)? IS THIS SCHEDULE VALID UNDER A 2 PHASE LOCKING SCHEDULER????

Shivam Gupta 3 asked in Databases Aug 3, 2017

by Shivam Gupta 3

516 views

0 votes

1 answer

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Test by Bikram | Mock GATE | Test 3 | Question: 34
Consider the following schedule: $S =$ ${R1(A),R2(B),W2(A),W1(A)}$ Assume that Transaction $T1$ has started execution before the Transaction $T2$. Then, the schedule is: Allowed under Basic Timestamp Protocol ... Allowed under both Basic Timestamp Protocol and Thomas Write Rule. Not allowed under both Basic Timestamp Protocol and Thomas Write Rule.

Bikram asked in GATE Feb 9, 2017

by Bikram

224 views

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