Parsed test spec with 2 sessions

starting permutation: s1_begin s2_begin s1_sum s2_sum s1_delete s2_delete s1_commit s2_commit
step s1_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s2_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s1_sum: SELECT ws_sum();
ws_sum            
------------------
4500, entry counts
(1 row)

step s2_sum: SELECT ws_sum();
ws_sum            
------------------
4500, entry counts
(1 row)

step s1_delete: DELETE FROM ws WHERE ctid = '(0,1)';
step s2_delete: DELETE FROM ws WHERE ctid = '(0,2)';
step s1_commit: COMMIT;
step s2_commit: COMMIT;
ERROR:  could not serialize access due to read/write dependencies among transactions

starting permutation: s1_dirty s1_begin s2_begin s1_sum s2_sum s1_delete s2_delete s1_commit s2_commit
step s1_dirty: DELETE FROM ws WHERE ctid = '(4,1)';
step s1_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s2_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s1_sum: SELECT ws_sum();
ws_sum                  
------------------------
4496, each entry counted
(1 row)

step s2_sum: SELECT ws_sum();
ws_sum                  
------------------------
4496, each entry counted
(1 row)

step s1_delete: DELETE FROM ws WHERE ctid = '(0,1)';
step s2_delete: DELETE FROM ws WHERE ctid = '(0,2)';
step s1_commit: COMMIT;
step s2_commit: COMMIT;
ERROR:  could not serialize access due to read/write dependencies among transactions

starting permutation: s1_begin s2_begin s1_sum s2_sum s1_insert s2_insert s1_commit s2_commit
step s1_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s2_begin: BEGIN ISOLATION LEVEL SERIALIZABLE;
step s1_sum: SELECT ws_sum();
ws_sum            
------------------
4500, entry counts
(1 row)

step s2_sum: SELECT ws_sum();
ws_sum            
------------------
4500, entry counts
(1 row)

step s1_insert: INSERT INTO ws VALUES (100);
step s2_insert: INSERT INTO ws VALUES (200);
step s1_commit: COMMIT;
step s2_commit: COMMIT;
ERROR:  could not serialize access due to read/write dependencies among transactions