3. In the context of Database system, a transaction can be seen as a logical unit...

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3. In the context of Database system, a transaction can be seen as a logical unit that is independently executed for data retrieval or updates. The table below depict the scheduling of two concurrent transactions T and T2. T R(A) T2 W(A) R(B) W(B) R(C) W(C) Commit Commit - Note that R mean read, W mean write - The W (write) stated here is equivalent to an update (meaning the data is modified) Is this schedule above serializable? (5 marks) 4. consider the following two 2 transactions: Initial state A=0 and B=0. o T:read (A) read (B); If (A==B) B++; write (B); o T2: read (B) read (A) If (B=0) A++; write (A); Let the consistence requirement be A=0 or B=0, A=B=0 initial values a). Show that [T1, T2], [T2, Ti] serial execution of these transactions preserves consistency. (5 marks) b). Show that concurrent execution produces serial schedule, assuming that read statement refer to "select column from table". (3 marks) c). Is the concurrent execution producing serializing schedule? (2 marks) 3. In the context of Database system, a transaction can be seen as a logical unit that is independently executed for data retrieval or updates. The table below depict the scheduling of two concurrent transactions T and T2. T R(A) T2 W(A) R(B) W(B) R(C) W(C) Commit Commit - Note that R mean read, W mean write - The W (write) stated here is equivalent to an update (meaning the data is modified) Is this schedule above serializable? (5 marks) 4. consider the following two 2 transactions: Initial state A=0 and B=0. o T:read (A) read (B); If (A==B) B++; write (B); o T2: read (B) read (A) If (B=0) A++; write (A); Let the consistence requirement be A=0 or B=0, A=B=0 initial values a). Show that [T1, T2], [T2, Ti] serial execution of these transactions preserves consistency. (5 marks) b). Show that concurrent execution produces serial schedule, assuming that read statement refer to "select column from table". (3 marks) c). Is the concurrent execution producing serializing schedule? (2 marks)