# Read-write-unique test.

setup
{
  CREATE TABLE test (i integer PRIMARY KEY);
}

teardown
{
  DROP TABLE test;
}

session s1
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step r1 { SELECT * FROM test; }
step w1 { INSERT INTO test VALUES (42); }
step c1 { COMMIT; }

session s2
setup { BEGIN ISOLATION LEVEL SERIALIZABLE; }
step r2 { SELECT * FROM test; }
step w2 { INSERT INTO test VALUES (42); }
step c2 { COMMIT; }

# Two SSI transactions see that there is no row with value 42
# in the table, then try to insert that value; T1 inserts,
# and then T2 blocks waiting for T1 to commit.  Finally,
# T2 reports a serialization failure.
#
# (In an earlier version of Postgres, T2 would report a unique
# constraint violation).

permutation r1 r2 w1 w2 c1 c2

# If the value is already visible before T2 begins, then a
# regular unique constraint violation should still be raised
# by T2.

permutation r1 w1 c1 r2 w2 c2