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<head><title>Automatic refactoring </title>
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<h1><a name="kanchor91"></a>Automatic Refactoring</h1>
<p>In simple cases db4o handles schema changes automatically:</p>
<ul>
<li value="1">When you <b>add</b> a new field, db4o automatically starts storing the new data. Older instances of your stored class have the default value in the new field.</li>
<li value="2">When you <b>remove</b> a field, db4o ignores the stored value for that field. The stored value is not removed from the database until you update the object or run a defragmentation. Meanwhile the old values are still accessible with the <a href="field_type_change.htm">StoredClass/StoredField API</a>.</li>
<li value="3">You can <![CDATA[ ]]><b>add an interface</b> to a class any time. The db4o operations are not affected by interfaces.</li>
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