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Recent questions tagged transaction-and-concurrency

3 votes

2 answers

271

How to check if a schedule is 2PL or not?
How to check if a schedule is allowed in 2PL or not? S1:R2(A)W1(B)W1(C)R3(B)R2(B)R1(A)R2(C)W3(A) S2:W2(A)W1(A)W3(A)W2(B)W1(B)W3(B)

reena_kandari asked in Databases Jul 22, 2017

by reena_kandari

5.6k views

1 vote

0 answers

272

[ DBMS ] AVL and BST
Classify the best balanced tree DS from AVl and B+trees for below applications 1. Main memory application with 100 keys 2. Secondary memory application with 100 keys 3. Main memory application with 1 million keys 4. Secondary memory application with 1 million keys

rahul sharma 5 asked in Databases Jul 16, 2017

by rahul sharma 5

140 views

1 vote

1 answer

273

[DBMS] Lost Update and WW
Consider thw following schedules :- S1 :- W1(A) W2(A) W1(B) W2(B) S2:- W1(A) R2(A) W2(A) W2(B) W1(B) Assume that schedule S1 is failed after performing W1(B). Which of the following options are true? a.) S1 and S2 has lost update ... lost update problem and WW problem c) S1 has WW problem and S2 has lost update problem d) S1 has lost update problem and s2 has WW problem

rahul sharma 5 asked in Databases Jul 16, 2017

by rahul sharma 5

1.1k views

2 votes

0 answers

274

[DBMS] Conflicting pairs
True / false? 1. Serial schedules don't have any conflicting pairs. 2. Serializable schedules don't have any conflicting pairs

rahul sharma 5 asked in Databases Jul 16, 2017

by rahul sharma 5

349 views

4 votes

1 answer

275

DBMS Number of serializable schedules
Consider thw following transactions:- T1 :- r1(A) w1(A) r1(B) w1(B) T1 :- r2(A) w2(A) r2(B) w2(B) a) Number of schedules serializable as t1->t2? b) Number of schedules serializable as t2->t1?

rahul sharma 5 asked in Databases Jul 12, 2017

by rahul sharma 5

1.0k views

11 votes

3 answers

276

[DBMS] Number of view equal schedules
Number of schedules view equal to following schedule :- r1(A), w1(B), r2(A), w2(B), r3(A), w3(B)

rahul sharma 5 asked in Databases Jul 10, 2017

by rahul sharma 5

8.4k views

0 votes

1 answer

277

Ramakrishan
In some part, it is given we cannot decide, why we cannot decide view serializability and recoverability? And, explain the solution for 7th part.

prasoon raghav asked in Databases Jun 21, 2017

by prasoon raghav

281 views

11 votes

3 answers

278

ISRO2017-6
ACID properties of a transactions are Atomicity, consistency, isolation, database Atomicity, consistency, isolation, durability Atomicity, consistency, integrity, durability Atomicity, consistency, integrity, database

sh!va asked in Databases May 7, 2017

by sh!va

4.0k views

5 votes

3 answers

279

ISRO 2017-5
Which of the following concurrency control protocol ensures both conflict and free from deadlock? , Time stamp ordering 2 Phase locking Both (a) and (b) None of the above

sh!va asked in Databases May 7, 2017

by sh!va

4.5k views

1 vote

3 answers

280

Concurrency Control
Consider the following schedules: S1: W2(x), W1(x), R3(x), R1(x), W2(y), R3(y), R3(z), R2(x) S2: R3(z), W2(x), W2(y), R1(x), R3(x), R2(z), R3(y), W1(x) S3: R2(z), W2(x), W2(y), W1(x), R1(x), R3(x), R3(z), R3(y) Which one of the above schedules are conflict equivalent?

Ml_Nlp asked in Databases Apr 17, 2017

by Ml_Nlp

1.7k views

1 vote

1 answer

281

Pessimistic time stamp ordering vs optimistic time stamp ordering
What is the difference between Pessimistic time stamp ordering and optimistic time stamp ordering.

LavTheRawkstar asked in Databases Mar 17, 2017

by LavTheRawkstar

2.2k views

0 votes

1 answer

282

Multiversion Timestamp ordering vs time stamp ordering
What is the advantage and drawback of Multiversion Timestamp ordering in comparison with ordering Time stamp ordering? anyone please also explain what is this multiversion Timestamp ordering and what is the Timestamp ordering in simple words please?

LavTheRawkstar asked in Databases Mar 17, 2017

by LavTheRawkstar

1.8k views

0 votes

0 answers

283

Doubt in two phase Commit Protocol
In two phase Commit Protocol,why can blocking be completely eliminated even when participants elect a new Coordinator ?

LavTheRawkstar asked in Databases Mar 17, 2017

by LavTheRawkstar

494 views

1 vote

2 answers

284

Essential differences in the Lock based Protocols and Time-stamp based proctols?
Essential differences in the Lock based Protocols and Time-stamp based proctols?

LavTheRawkstar asked in Databases Mar 17, 2017

by LavTheRawkstar

2.6k views

1 vote

2 answers

285

write locks are released after last operation of transaction but before its commit ! explain
Somebody please explain this i am not able to understand please given an example of transaction or explain in hindi what the question and answer is please explain somebody please Here i am posting the Entire ... please explain which choice is correct and which is wrong I am not able to understand it.

LavTheRawkstar asked in Databases Mar 16, 2017

by LavTheRawkstar

1.1k views

126 votes

18 answers

286

GATE CSE 2017 Set 2 | Question: 44
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 ______

Madhav asked in Databases Feb 14, 2017

by Madhav

56.2k views

0 votes

1 answer

287

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

181 views

2 votes

1 answer

288

Database 2PL and Timestamp doubt
I)All schedules that are allowed under 2PL are also allowed under Timestamp?? Is vice versa true?? II)Plz explain by giving example. I have read that there are schedules that are allowed under 2PL but not under Timestamp and vice versa, ... ?? IV) Are all view serializable allowed under Timestamp(Thomas write rule)??? Explanation along with example would be helpful.

Rahul Jain25 asked in Databases Feb 4, 2017

by Rahul Jain25

1.8k views

1 vote

2 answers

289

concurrency control
IS CONSERVATIVE 2PL ALSO RIGOROUS?? WHEN WE SAY THAT A TRANSACTION FOLLOWS CONSERVATIVE TWO PHASE LOCKING, DOES IT AUTOMATICALLY ALSO IMPLY RIGOROUS 2PL??

sushmita asked in Databases Jan 31, 2017

314 views

1 vote

1 answer

290

MadeEasy Subject Test: Databases - Transactions

pranjalgennext asked in Databases Jan 30, 2017

by pranjalgennext

228 views

1 vote

3 answers

291

MadeEasy Subject Test: Databases - Transactions
S: R1(A), R3(D), W1(B), R2(B), R4(B), W2(C), R5(C), W4(E), R5(E), W5(B) Number of serial schedules which are view equal to above S are __. Polygraph that I drew:

sivajagsa asked in Databases Jan 30, 2017

919 views

1 vote

2 answers

292

Ace Test Series: Databases - Transactions
Whether the given schedule is conflict serializable or view serializable or none.

Kai asked in Databases Jan 29, 2017

by Kai

533 views

7 votes

3 answers

293

view serializable
$S: R_1(A),R_2(B),W_2(A),W_3(C),R_4(C),R_3(A),W_3(B),R_4(A),W_2(B),W_4(B),W_3(A)$ View serializable or not?

Supremo asked in Databases Jan 28, 2017

1.6k views

1 vote

1 answer

294

Self Doubt
Do commit operations matter while checking serilizability?If yes why?

Gate Madrista asked in Databases Jan 28, 2017

by Gate Madrista

381 views

0 votes

1 answer

295

MadeEasy Subject Test: Databases - Transactions

vaishali jhalani asked in Databases Jan 27, 2017

by vaishali jhalani

185 views

0 votes

1 answer

296

MadeEasy Subject Test: Databases - Transactions
Here T1 T2 T4 T5 will come in this order only and for T3 we have 5 positions So number of schedules will be 5 which are view eq to given schedule. But ans given is 10

vaishali jhalani asked in Databases Jan 26, 2017

by vaishali jhalani

157 views

1 vote

1 answer

297

Test by Bikram | Mock GATE | Test 2 | Question: 51
Which of the following schedules are conflicts serializable? S1: $r1$ $\left ( A \right )$, $r1$\left ( B \right )$, $w2$\left ( A \right )$, $r3$ $\left ( A \right )$, $w1$\left ( B \right )$, $w3$ $\left ( A \right )$, $r2$ $\left ( B \ ... $w2$ $\left ( C \right )$, $r3$, $\left ( C \right )$ $S1,S3$ only $S2,S3$ only $S1,S2$ only $S1, S2, S3$

Bikram asked in GATE Jan 24, 2017

by Bikram

197 views

1 vote

1 answer

298

MadeEasy Subject Test: Databases - Transactions
Consider the following schedule S : r1(A) w2(A) r3(A) w4(A) r5(A) w6(A) The number of schedules equal to given schedule(s) which not conflict equal to schedule(s) are _______.

Çșȇ ʛấẗẻ asked in Databases Jan 23, 2017

by Çșȇ ʛấẗẻ

210 views

1 vote

1 answer

299

MadeEasy Subject Test: Databases - Transactions
Statement # 5 is correct or not? how?

Jason_Roy asked in Databases Jan 21, 2017

221 views

1 vote

5 answers

300

Conflict Serializable and Timestamp based protocol
I know that every schedule produced by the Timestamp-based protocol is conflict serializable. But is vice versa is true? Means is all conflict serializable schedules produced by timestamp based protocol ?

lifeisshubh asked in Databases Jan 21, 2017

1.8k views

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Recent questions tagged transaction-and-concurrency