Consider the following transactions T1, T2, and T3, with operations Read(X) and Write(X), where X is a data item:T1: Read(X), Write(X)T2: Write(X)T3: Read(X), Write(X)In the given scenario, which schedule is an example of a recoverable schedule?T1, T2, T3T1, T3, T2T2, T1, T3T3, T1, T2
Question
Consider the following transactions T1, T2, and T3, with operations Read(X) and Write(X), where X is a data item:T1: Read(X), Write(X)T2: Write(X)T3: Read(X), Write(X)In the given scenario, which schedule is an example of a recoverable schedule?T1, T2, T3T1, T3, T2T2, T1, T3T3, T1, T2
Solution
A recoverable schedule is one where, for any pair of transactions Ti and Tj, if Tj reads a data item previously written by Ti, then the commit operation of Ti appears before the commit operation of Tj. This ensures that if Ti fails and needs to be rolled back, Tj has not yet committed, so the system is in a consistent state.
Let's analyze the given schedules:
-
T1, T2, T3: This is not recoverable. T2 writes X before T1 commits, so if T1 needs to be rolled back, T2 would have already committed, leading to an inconsistent state.
-
T1, T3, T2: This is recoverable. T1 commits before T3 reads X, and T3 commits before T2 writes X. So, if any transaction needs to be rolled back, it won't affect the others.
-
T2, T1, T3: This is not recoverable. T2 writes X before T1 and T3 commit, so if either T1 or T3 needs to be rolled back, T2 would have already committed, leading to an inconsistent state.
-
T3, T1, T2: This is not recoverable. T3 reads X before T1 commits, and T2 writes X before T3 commits. So, if either T1 or T3 needs to be rolled back, it would affect the others.
So, the only recoverable schedule among the given options is T1, T3, T2.
Similar Questions
Consider the following transactions T1, T2, and T3, with operations Read(X) and Write(X), where X is a data item:T1: Read(X), Write(X)T2: Write(X)T3: Read(X), Write(X)If transaction T2 fails after its Write(X) operation, which of the following schedules ensures recoverability?T1, T2, T3T1, T3, T2T2, T1, T3T3, T1, T2
Consider the following transactions T1, T2, and T3, with operations Read(X) and Write(X), where X is a data item:T1: Read(X), Write(X)T2: Write(X)T3: Read(X), Write(X)In the given scenario, which schedule is an example of an irrecoverable schedule?T1, T2, T3T1, T3, T2T2, T1, T3T3, T1, T2
Given a schedule S for transactions T1 and T2 with set of read and write operations, S: R1(X) R2(X) R2(Y) W2(Y) R1(Y) W1(X). Identify, whether given schedule is equivalent to serial schedule or not?
Consider the three transactions T1, T2, and T3, and the schedules S1 and S2given below. State whether each schedule is serializable or not. If a schedule is serializable, write down the equivalent serial schedule(s). T1: r1 (X); r1 (Z); w1 (X); T2: r2 (Z); r2 (Y); w2 (Z); w2 (Y); T3: r3 (X); r3 (Y); w3 (Y); S1: r1 (X); r2 (Z); r1 (Z); r3 (X); r3 (Y); w1 (X); w3 (Y); r2 (Y); w2 (Z); w2 (Y); S2: r1 (X); r2 (Z); r3 (X); r1 (Z); r2 (Y); r3 (Y); w1 (X); w2 (Z); w3 (Y); w2 (Y);
Let Ri(z) and Wi(z) denote read and write operations on a data element z by a transaction Tjr respectively. Consider the schedule S with four transactions. S: R4(x) * R2(x) * R3(x) * R1(y) * W1(y) * W2(x) * W3(y) * R4(y) Which one of the following serial schedules is conflict equivalent to S?T1 -> T3 -> T4 -> T2T1 -> T4 -> T3 -> T2T4 -> T1 -> T3 -> T2T3 -> T1 -> T4 -> T2
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.