Problem 1 Consider a database consisting of a single relation M a) The following two transactions T1 and T2 run concurrently on this database T1 BEGIN TRANSACTION S1 update M set B B 10 where A 1 S2 update M set B B 10 where A 2 COMMIT T2 BEGIN TRANSACTION S3 select sum(B) from M COMMIT Indicate at least one isolation level (if exist) that may make possible to see zero as output for T2 b) The following two transactions run concurrently on this database T1 BEGIN TRANSACTION S1 insert into M values (3,100) COMMIT T2 BEGIN TRANSACTION S2 select sum(B) from M S3 select sum(B) from M COMMIT For what isolation levels, T2 may see a different value as the output of the select sum(B) from M statements Problem 1 Consider a database consisting of a single relation M 10 0 2 a) The following two transactions T1 and T2 run concurrently on this database T1 BEGIN TRANSACTION S1 update M set B B 10 where A 1 S2 update M set B B 10 where A 2 COMMIT T2 BEGIN TRANSACTION S3 select sum(B) from M COMMIT Indicate at least one isolation level (if exist) that may make possible to see zero as output for T2 The following two transactions run concurrently on this database T1 BEGIN TRANSACTION b) S1 insert into M values (3,100) COMMIT T2 BEGIN TRANSACTION S2 select sum(B) from M S3 select sum(B) from M COMMIT For what isolation levels, T2 may see a different value as the output of the select sum(B) from M statements

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Problem 1 Consider a database consisting of a single relation M: a) The following two transactions T1 and T2 run concurrently on this database: T1

Problem 1 Consider a database consisting of a single relation M: a) The following two transactions T1 and T2 run concurrently on this database: T1 BEGIN TRANSACTION S1: update M set B = B-10 where A=1 S2: update M set B = B+10 where A=2 COMMIT; T2 BEGIN TRANSACTION S3: select sum(B) from M COMMIT Indicate at least one isolation level (if exist) that may make possible to see zero as output for T2. b) The following two transactions run concurrently on this database: T1 BEGIN TRANSACTION S1: insert into M values (3,100) COMMIT; T2 BEGIN TRANSACTION S2: select sum(B) from M S3: select sum(B) from M; COMMIT For what isolation levels, T2 may see a different value as the output of the select sum(B) from M statements? image text in transcribed

Problem 1 Consider a database consisting of a single relation M: 10 0 2 a) The following two transactions T1 and T2 run concurrently on this database: T1 BEGIN TRANSACTION S1: update M set B -B-10 where A-1 S2: update M set B = B+10 where A-2 COMMIT T2 BEGIN TRANSACTION S3: select sum(B) from M COMMIT Indicate at least one isolation level (if exist) that may make possible to see zero as output for T2. The following two transactions run concurrently on this database: T1 BEGIN TRANSACTION b) S1: insert into M values (3,100) COMMIT T2 BEGIN TRANSACTION S2: select sum(B) from M S3: select sum(B) from M; COMMIT For what isolation levels, T2 may see a different value as the output of the select sum(B) from M statements