# Two IDs test # # Small, simple test showing read-only anomalies. # # There are only four permutations which must cause a serialization failure. # Required failure cases are where s2 overlaps both s1 and s3, but s1 # commits before s3 executes its first SELECT. # # If s3 were declared READ ONLY there would be no false positives. # With s3 defaulting to READ WRITE, we currently expect 12 false # positives. Further work dealing with de facto READ ONLY transactions # may be able to reduce or eliminate those false positives. setup { create table D1 (id int not null); create table D2 (id int not null); insert into D1 values (1); insert into D2 values (1); } teardown { DROP TABLE D1, D2; } session "s1" setup { BEGIN ISOLATION LEVEL SERIALIZABLE; } step "wx1" { update D1 set id = id + 1; } step "c1" { COMMIT; } session "s2" setup { BEGIN ISOLATION LEVEL SERIALIZABLE; } step "rxwy2" { update D2 set id = (select id+1 from D1); } step "c2" { COMMIT; } session "s3" setup { BEGIN ISOLATION LEVEL SERIALIZABLE; } step "ry3" { select id from D2; } step "c3" { COMMIT; }