* Copyright 2007 Daniel Spiewak
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
Tags a specific method as representing a field who's value should be
auto-generated by the database in some sort of numeric sequence
(usually ascending order). Not all databases support this function
as a field modifier. For example, PostgreSQL requires the use of the
SERIAL type. Thus, this annotation imposes priority
over the defined type and should only be used on
long fields (
short is also acceptable if
great care is taken).
For databases which really have no way of supporting this exact functionality (like Oracle), implementation may be omitted as long as the 90% case is still covered. For example, the Oracle implementation of this property relies on the fact that PRIMARY KEY fields are already auto-generated if no value is specified.
This annotation is only relevant to migrations. It has no effect upon "runtime" entity usage.