madeeasy work book

Question

T1: r1(A) r1(B) w1(B)

T2:r2(A) r2(B) w2(B)

1)how many concurrent schedules between t1 and t2?

2) how many non serial achedule are serializable?

3) how many schedules serializable as T1-->T2

Am not getting how to find all these. please someone help me.

thanku in advance

Comments

anyone plz tell the procedure how to find it?

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how you got 3 ?? plz help

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i think ans is 4

Answer 1

.............

Comments

for T1-->T2

Why you have not considered R(B)

Similarily for T2--->T1

Why you have not considered R(B)

PLZ clarify

Answer 2

1.There will be 20 schedules.....total schedules possible will be 6!/3!3!....that is 20...but as concurrent schedules are non serial schedules.....we will have 18 as the answer.......

2.There will be 6 non serial schedules that will be serializable......

3.There will be 4 schedules serializable as t1->t2

Comments

can you please tell me the procedure how to find it am not getting the procedure ?

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@aaru14

1.(n1+n2+n3+....+np)!/(n1!*n2!*....*np!) {n1,2 are  no of operations in p transaction)

2.(no of total serial schedule ..P!)

3.schedule to be serializable form T1-T2 all the conflicting action must be form T1 to T2 there in r2(b),w2(b) must be after w1(b) and r2(a) could be arrange in (three+1) way(1.between r1(b) and w1(b) 2.between r1(a) and r1(b) 3. at the starting of T2 4.after w1(b).

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i think 4 ways......r2(a) can be arranged before r1(a)...after r1(a) before r1(b) ......after r1(b) before w1(b)......and after w1(b).......

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Oh!  @himanshu19
correct