Consider a database with tables R1(A) and R2(B) and transaction T1: T1: set transaction isolation level repeatable read; Select * from R1 Select * from R1 Select * from R2 Suppose table R1 initially has one tuple with value A=3 and table R2 initially has one tuple with value B=6. Consider the following possible transactions T2, executed around the same time as T1. Which one of them can cause the two transactions to exhibit nonserializable behavior? a) T2: set transaction serializable; update R1 set A=4; delete from R2 where B=6; commit; b) T2: set transaction serializable; delete from R2; insert into R2 values (6); commit; c) T2: set transaction serializable; update R2 set B=7; commit; d) T2: set transaction serializable; insert into R2 values (5); delete from R1 where A=2; commit;

Problem 2 Consider a database with tables R1(A) and R2(B) and transaction T1: T1: set transaction isolation level repeatable read; Select from R1 Select from R1 Select * from R2 Suppose table R1 initially has one tuple with value A-3 and table R2 initially has one tuple with value B-6. Consider the following possible transactions T2, executed around the same time as T1. Which one of them can cause the two transactions to exhibit nonserializable behavior? a) T2: set transaction serializable; update R1 set A-4; delete from R2 where B-6; commit; b) T2: set transaction serializable; delete from R2; insert into R2 values (6); commit; c) T2: set transaction serializable; update R2 set B-7; commit; d) T2: set transaction serializable; insert into R2 values (5); delete from R1 where A-2; commit