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Understanding limitations of schema evolution

#1
yodayoda
Joined on 2014-10-31
Hi, I am trying to understand the limitations of schema evolution and have read the material on http://www.objectdb.com/java/jpa/entity/schema as well as the link therein regarding manual schema update when changing a field’s name Yet, i am confused regarding how to handle the case where one re-factors a class by moving one if it's Fields to a different class. Is this case managable? Thanks
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#2
supportsupport
Joined on 2010-05-03

If a persistent field is moved to a super class or a sub class (i.e. changes hierarchy but still remains relevant to objects that contains values of that field), ObjectDB handles this situation automatically. However, if the field is moved between different classes with different objects, ObjectDB cannot map automatically the old objects that had the field values to new objects, and you will have to write code for making this schema change.

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#3
yodayoda
Joined on 2014-10-31
Thanks for your reply. Could you please elaborate more on the nature and complexity of the code that one has to write in the second case (namely moving a field between different classes of defferent objects)? Going over the schema update page http://www.objectdb.com/java/jpa/setting/schema it is not clear how to handle this case.
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#4
supportsupport
Joined on 2010-05-03

Obviously it depends on the specific required changes.

It is like asking "Could you please elaborate more on the nature and complexity of the code that one has to write in order to develop an application?"

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