Schema evolution is a key problem in object-oriented systems because the dynamic nature of typical OODB applications calls for frequent changes in the schema.
模式演化是OO系统中一个很关键的问题。由于OODB的应用具有动态特征，因而模式要经常改动。
Schema evolution is a key problem in object-oriented systems because the dynamic nature of typical OODB applications calls for frequent changes in the schema.
模式演化是OO系统中一个很关键的问题。由于OODB的应用具有动态特征，因而模式要经常改动。
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