标签： hive user-defined-functions
GenericUDF＃initialize方法何时应返回PrimitiveObjectInspectorFactory.writableStringObjectInspector，何时应返回PrimitiveObjectInspectorFactory.javaStringObjectInspector（针对结果类型）？
PrimitiveObjectInspectorFactory.writableStringObjectInspector
PrimitiveObjectInspectorFactory.javaStringObjectInspector