没有成员的列 [英] Column without member

问题描述

使用Hibernate，我们试图使它为抽象类创建一个附加列-但是我们不能向该类添加新成员(大规模消耗内存).我们需要让Hibernate创建模式(开发阶段hibernate.hbm2ddl.auto=update).

Using Hibernate we're trying to have it create an additional column to an abstract class - but we can't add a new member to this class (memory consumption in large scale). We need to have Hibernate create the schema (development phase, hibernate.hbm2ddl.auto=update).

假设我们有一个 MyClass 实体类，成员为 a，b，c ，我们希望Hibernate也创建一个列 d .该列在内存中不需要，仅在 MyClass 实例的保存/加载期间通过HQL/SQL进行访问.

Let's say we have a MyClass entity class with members a,b,c, and we would like Hibernate to also create a column d. This column is not needed in memory and will be accessed only via HQL/SQL during saving/loading times of MyClass instances.

可以做到吗?

注意:
1. Hibernate 3.6.0 Final + Oracle 11g +纯Java
2.我们使用注释，没有xml文件

Notes:
1. Hibernate 3.6.0 Final + Oracle 11g + pure Java
2. We use annotations, no xml files

推荐答案

将属性添加到类中，但使其变得懒惰(使用@Basic(fetch = FetchType.LAZY)批注).

Add the property to the class, but make it lazy (using the @Basic(fetch = FetchType.LAZY) annotation).

确保在构建时对类进行了检测:这是工作所需的.有关更多详细信息，请参见本章文档.

Make sure your classes are instrumented at build time: it's needed for this to work. More details are available in this chapter of the documentation.

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