in Databases
857 views
1 vote
1 vote
Number of serial schedules but not conflict to schedule (S)

S: r1(A),r2(A),r3(A),r4(A),w1(B),w2(B),w3(B),w4(B)
in Databases
857 views

2 Comments

do you mean the no.of serial schedules that are conflict equivalent to the above schedule?

If thats your question then i got only 1 serial schedule : T1-T2-T3-T4
0
0
Please explain it..
0
0

1 Answer

0 votes
0 votes
Number of serial schedules which are view equivalent to S but not conflict equivalent to schedule S

Conflict equivalent Schedule is

T1->T2->T3->T4

view equivalent Schedule are

1. first read same

2. final write same

3. w-R dependency on same on same data item

T4 should be last bcz it is final write. T1,T2,T3 can be in any order for view equivalent. Here read operation doesn't matter bcz it is on single data item

Answer is 3!-1=5

4 Comments

edited by
Number of conflict equivalent schedule are

w1->w2->w3->w4 in which r1,r2,r3,r4 arranged as 1x3x5x7x1=105

Number of view equivalent schedule are

T1->T2->T3->T4 in which r1,r2,r3,r4 arranged as 1x3x5x7x3!=630 (3! for arranging w1->w2->w3->w4 as w4 is final write )

Then No of view equivalent which are not conflict equivalent schedule =630-105=525

 

Question need correction bcz Serial is subset of Conflict is subset of View
0
0

@G4TE Hunter

I understand your logic of finding conflict equivalent schedules..but what are you getting after 630-105? These are the no. of schedules which are only view equivalent and not conflict equivalent right? And what does the question ask for? 

0
0

@Shubhgupta the question had this description only.

0
0

Related questions

0 votes
0 votes
1 answer
3