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Consider the following database schedule with two transactions, T1 and T2. S = r2(X); r1 (X); r2(Y); w1(X); r1 (Y); w2(X); a1; a2 where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti. Which one of the following statements about the above schedule is TRUE? 

Consider the following database schedule with two transactions, T1 and T2. S = r2(X); r1 (X); r2(Y); w1(X); r1 (Y); w2(X); a1; a2 where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti. Which one of the following statements about the above schedule is TRUE?  Correct Answer S does not have a cascading abort

Concept:

Cascadeless schedule

It is one in which each pair of transaction Ti and Tj such that Tj reads the data that is written by Ti than the commit or abort operation of Ti should appear before the read operation of Tj

T1

T2

 

r(x)

r(x)

 

 

r(y)

w(x)

 

r(y)

 

 

w(x)

abort(a)

 

 

abort(a)

 

Since there are no write-in T1 read by T2. Hence S is cascadeless schedule, that is, S does not have a cascading abort

Related Questions

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