In the update trigger, you need to delete the corresponding feature if one of the coordinates becomes null.
在更新触发器中，如果坐标值之一变成null，那么需要删除对应的特性。
2
The update trigger is more complicated: if the update causes an exception, you have to delete the existing feature row, just as for null coordinates.
更新触发器比较复杂：如果更新导致异常，那么必须删除现有的特性行，就像处理null坐标一样。
3
An alternative way of creating a heap dump is to use another useful Rubinius feature: the Query Agent, which allows monitoring tools to access Rubinius information as well as trigger certain actions.