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/* Changing the layout to use less space for mobiles */
@media screen and (max-device-width: 480px), screen and (-webkit-min-device-pixel-ratio: 2) {
#email-body { min-width: 30em !important; }
#email-page { padding: 8px !important; }
#email-banner { padding: 8px 8px 0 8px !important; }
#email-avatar { margin: 1px 8px 8px 0 !important; padding: 0 !important; }
#email-fields { padding: 0 8px 8px 8px !important; }
#email-gutter { width: 0 !important; }
}
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<div id="email-action" style="padding: 0 0 8px 0;font-size:12px;line-height:18px;">
<a class="user-hover" rel="pierre.sion@keynectis.com" id="email_pierre.sion@keynectis.com" href="https://hibernate.onjira.com/secure/ViewProfile.jspa?name=pierre.sion%40keynectis.com" style="color:#6c797f;">Pierre Sion</a>
commented on <img src="https://hibernate.onjira.com/images/icons/bug.gif" height="16" width="16" border="0" align="absmiddle" alt="Bug"> <a style='color:#6c797f;text-decoration:none;' href='https://hibernate.onjira.com/browse/HHH-7862'>HHH-7862</a>
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<a style='color:#6c797f;text-decoration:none;' href='https://hibernate.onjira.com/browse/HHH-7862'><strong>Improper "unique" constraint in auto-generated schema (DDL) when a Java Map value involves non-primitive types</strong></a>
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<div class="comment-block" style="background-color:#edf5ff;border:1px solid #dddddd;color:#000000;padding:12px;"><p>Hello, thank you for your reply, sorry if I did not make myself clear in the first place. In the above example, the "@OneToMany" annotation represents the mapping of a <b>Java Map object</b>. The "Hibernate Reference Documentation 3.6.10.Final" indeed states in chapter "7.2.2.2. Maps" that it is the correct way to "map a Map" (so to speak).</p>
<p>From the database point of view, the Map is represented by an association table (named "customer_order" in the above example), which has 3 columns:</p>
<ul>
<li>one column referencing the Map's owner ("customer_id" above)</li>
<li>one column holding the Map's key ("somekey" above)</li>
<li>one column referencing the Map's value ("order_id" above)</li>
</ul>
<p>So far so good. My point is, a seemingly improper "unique" database constraint is automatically generated on the "order_id" column of the "customer_order" relation table (when Hibernate is configured to generate the DDL automatically). This prevents different Customers to map the same Order object (not really useful in the real customer-order life, but you see the technical point). May be I interpret wrongly the true meaning of "@OneToMany", which inconditionally imposes distinct Orders, whatever the underlying collection nature (Map in my case). May be I should have used the newer annotation "@CollectionOfElements" instead of "@OneToMany" (unfortunately I do not have my testing environment at disposal for the moment), and in this case the bug is only related to the Hibernate Reference Documentation.</p>
<p>What I notice, though, when the Map value is a "primitive" object (such as a String) instead of an "Order", the "unique" DDL constraint is not generated. The DDL generation behaviour thus does not seem consistent at least.</p></div>
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