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Recent questions tagged transaction-and-concurrency

3 votes

1 answer

241

No. Of serial schedules view equal to S
No. Of serial schedules view equal to S S: R1(A), R3(D), W1(B), R2(B), W3(B), R4(B), W2(C), R5(C), W4(E), R5(E), W5(B) . If possible please provide detailed solutions. Thank you in advance

thepeeyoosh asked in Databases Jan 6, 2018

3.2k views

0 votes

1 answer

242

We have 2 Schedule S1 and S2 ... There are no Conflict Operation in S1 and S2.
We have 2 Schedule S1 and S2 ... There are no Conflict Operation in S1 and S2. So can we say they are conflict equivalent ?

Anup patel asked in Databases Dec 26, 2017

532 views

1 vote

0 answers

243

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

942 views

0 votes

0 answers

244

doubt in strict schedule
To determine it is strict we have to go from left to right or from right to left ??

sumit goyal 1 asked in Databases Dec 25, 2017

by sumit goyal 1

626 views

0 votes

0 answers

245

soumayan bandhu asked in Databases Dec 23, 2017

by soumayan bandhu

310 views

5 votes

2 answers

246

Timestamp Ordering Protocol
Assume basic timestamp ordering protocol and that time starts from $1$, each operation takes unit amount of time and start of transaction $T_i$ is denoted as $S_i$. The table of timestamp is given below: Find $rts(a), wts(a), rts(b)$ and $wts(b)$ at the end 1, 5, 2, 5 1, 7, 3, 3 3, 7, 3, 7 1, 7, 3, 7

ankitgupta.1729 asked in Databases Dec 16, 2017

by ankitgupta.1729

7.2k views

1 vote

0 answers

247

DBMS schedules
S:- r1(a) , w2(a) c2 w1(a) c1 w3(a) c3 Is this strict recoverable and serializable ? c1 means commit of transaction T1

rahul sharma 5 asked in Databases Dec 16, 2017

by rahul sharma 5

984 views

0 votes

1 answer

248

Transactions & Concurrency Control
The above question has a blind write so it should be View Serializable. But can it be Conflict Serializable?

Kaustubh _15 asked in Databases Dec 15, 2017

by Kaustubh _15

488 views

0 votes

2 answers

249

DBMS Phantom Read
A Phantom Read is when two SELECT queries within the same transaction return a different number of rows. But if the number of rows returned is the same and the data is different, is that also considered as Phantom?

Sumaiya23 asked in Databases Dec 15, 2017

1.5k views

1 vote

1 answer

250

#dbms locking protocol
does graph based and time stamp ordering protocol ensure freedom from cascadeless rollback?

iarnav asked in Databases Dec 11, 2017

by iarnav

1.4k views

1 vote

1 answer

251

#DBMS FAIL V/S ABORT
what is the difference btw ABORT AND FAIL IN TRANSACTION? PLEASE EXPLAIN WITH A SMALL EXAMPLE!

iarnav asked in Databases Dec 11, 2017

by iarnav

1.1k views

–1 vote

1 answer

252

# dbms DIRTY READ
Please explain the concept of DIRTY READ In a simplified manner w/ a small example!

iarnav asked in Databases Dec 10, 2017

by iarnav

757 views

5 votes

1 answer

253

#DBMS Blind Write
Please explain the concept of Blind Write in a simplified manner w/ a small example!

iarnav asked in Databases Dec 10, 2017

by iarnav

13.5k views

1 vote

0 answers

254

Abhijeet_Kumar asked in Databases Dec 8, 2017

by Abhijeet_Kumar

383 views

2 votes

1 answer

255

Abhijeet_Kumar asked in Databases Dec 8, 2017

by Abhijeet_Kumar

378 views

3 votes

1 answer

256

Abhijeet_Kumar asked in Databases Dec 8, 2017

by Abhijeet_Kumar

588 views

4 votes

0 answers

257

Abhijeet_Kumar asked in Databases Dec 8, 2017

by Abhijeet_Kumar

413 views

3 votes

1 answer

258

2 Phase Locking
Consider the following schedule: S:R2(A) W1(B) W1(C) R3(B) R2(B) R1(A) C1 R2(C) C2 W3(A)C3 Please explain how it is allowed in 2 PL

shivangi5 asked in Databases Dec 6, 2017

1.3k views

3 votes

3 answers

259

VIEW SERIALIZABILITY
Consider the 2 transactions T1: R(A) W(A) W(B) T2: R(A) W(A) R(B) W(B) How many view serializable schedules are possible which are not conflict serializable? (A) 0 (B) 1 (C) 2 (D) 3

shivangi5 asked in Databases Dec 6, 2017

2.9k views

2 votes

1 answer

260

Conflict and View serializable

Parshu gate asked in Databases Dec 5, 2017

973 views

2 votes

1 answer

261

MadeEasy Test Series: Databases - Transactions
Consider the following schedule: S:r1(a) r3(d) w1(B) r2(B) r4(B) w2(C) r5(C) w4(E) r5(E) w5(B) How many serial schedules conflict equal to schedules (S)?

shivangi5 asked in Databases Dec 4, 2017

1.8k views

2 votes

1 answer

262

Transaction
How many concurrent schedules are conflict serializable of given transactions T1 and T2: T1 = r1(A) W1(A)R1(B)W1(B) T2 = R2(B)W2(B)R2(A)W2(A)

sunaina rawat asked in Databases Dec 4, 2017

by sunaina rawat

832 views

1 vote

0 answers

263

MadeEasy Test Series: Databases - Transactions
Deadlock prevention(wait-kill && wound-wait) is free from both starvation as well as deadlock? True or false?

learner_geek asked in Databases Dec 1, 2017

by learner_geek

370 views

1 vote

0 answers

264

MadeEasy Subject Test: Databases - Transactions
In below schedule (S) it has cascading abort or not?

learner_geek asked in Databases Dec 1, 2017

by learner_geek

432 views

2 votes

2 answers

265

recoverable and cascadeless

Parshu gate asked in Databases Nov 27, 2017

846 views

0 votes

1 answer

266

Database 2PL protocol
In 2PL protocol if all exclusive locks are acquired by transaction in increasing order of their accesses then is the 2PL starvation free ?

sumit chakraborty asked in Databases Nov 26, 2017

by sumit chakraborty

1.2k views

0 votes

0 answers

267

Strict schedule
This is strict schedule or not?

learner_geek asked in Databases Nov 25, 2017

by learner_geek

8.0k views

2 votes

1 answer

268

MadeEasy Subject Test: Databases - Transactions
The number of concurrent schedules can be formed with 3 transactions having 3, 2 and 1 operations respectively _________ I am getting 54 but the given ans is 60. My doubt is are serial schedules counted or not in the concurrent schedules.

shivangi5 asked in Databases Nov 24, 2017

659 views

2 votes

1 answer

269

Transaction Management
Which of the following protocols does not ensure conflict serializability and safety from deadlocks? Graph based protocols Two-phase locking protocol Time-stamp ordering protocol Both a & b

yogi_p asked in Databases Nov 18, 2017

by yogi_p

1.6k views

1 vote

1 answer

270

Consider a schedule with three transactions. T1, T2 and T3 executed concurrently.
The schedule is given below. Find out the category of the schedule S: R1(X),R2(Z)R1(Z),R3(X) W1(X) W3(Y) R2(Y) W2(Z) W2(Y) C1 C2 C3 Recoverable schedule Conflict Serializable Strict schedule None of these

techbrk3 asked in Databases Nov 9, 2017

1.7k views

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Recent questions tagged transaction-and-concurrency