Comment 1 for bug 1483564

actually it as not a bug, timestamps are converted to a normalize_time before samples stores, please take a look https://github.com/openstack/ceilometer/blob/master/ceilometer/dispatcher/database.py#L91

Final view depends on how precise was initial timestamp and we check it in a tests:
https://github.com/openstack/ceilometer/blob/master/ceilometer/tests/unit/dispatcher/test_db.py#L91
https://github.com/openstack/ceilometer/blob/master/ceilometer/tests/unit/dispatcher/test_db.py#L110