Question
Read the following scenario and address the following issues that are related to transaction and concurrency control. Assume that objects a1, a2, and a3 are
Read the following scenario and address the following issues that are related to transaction and concurrency control.
Assume that objects a1, a2, and a3 are managed by a server, which provides two operations to operate the objects.
read(a): returns the value of object a
write(a, v): assigns the value v to object a
Assume that the following two concurrent transactions T and U are performed on these objects
T: read(a2); read(a1); write(a2, a2-25); read(a3); write(a1, a1+52)
U: read(a3); read(a2); write(a2, a2+33); write(a3, a3-26)
Assume that the original values of a1, a2, and a3 are 111, 106 and 125 respectively. Answer the following questions based on the above scenario.
question (1) - If there is no concurrency control, transactions T and U may perform the following interleaving operations on objects a1, a2 and a3. What problem can be caused by the operations? Justify your answer.
--> When the above requirement in question (1) is satisfied, what would be the correct values of a1, a2 and a3 after T and U commit?
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