How the existing data to be if entity structure modified or deleted on GAE?

Posted by Eonil on Stack Overflow See other posts from Stack Overflow or by Eonil
Published on 2010-05-21T14:59:41Z Indexed on 2010/05/21 15:00 UTC
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jdo

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entity

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oodb

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class

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modification

GAE recommends using JDO/JPA. But I have serious question about using OODB like them. JDO based on user's class structure. And data structure should be modified continually as service advances. So,

If data(entity) class property being removed, what happened to existing data on the property?
If data(entity) class renamed for refactoring reason, how the JDO know those renaming? Or all data loss?

Major point is "How JDO/GAE/BigTable applies modification of class into existing entity structure and data?".

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