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PONHibernate deletes and recreates one-to-many associations even when I use a list
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  1. PONHibernate deletes and recreates one-to-many associations even when I use a list
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    copied!<p>OK,</p> <p>I've spent a long time researching this with NHibernate 3.3.1.4. The problem I have it that I have a list, like below:</p> <pre><code> &lt;class xmlns="urn:nhibernate-mapping-2.2" name="Domain.Model.Orders.Order, Domain.Model, Version=1.0.0.21730, Culture=neutral, PublicKeyToken=null" table="Orders"&gt; &lt;composite-id name="ID"&gt; &lt;key-property name="PartitionKey" type="System.Nullable`1[[System.Int64, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"&gt; &lt;column name="PartitionKey" /&gt; &lt;/key-property&gt; &lt;key-property name="ID" type="System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"&gt; &lt;column name="ID" /&gt; &lt;/key-property&gt; &lt;/composite-id&gt; &lt;version generated="always" name="SystemTimestamp" type="BinaryBlob" unsaved-value=""&gt; &lt;column name="SystemTimestamp" /&gt; &lt;/version&gt; &lt;list cascade="none" lazy="false" name="LineItems" table="OrderLineItems"&gt; &lt;key not-null="true"&gt; &lt;column name="PartitionKey" /&gt; &lt;column name="Order_ID" /&gt; &lt;/key&gt; &lt;index&gt; &lt;column name="ListIndex" /&gt; &lt;/index&gt; &lt;composite-element class="MemberSuite.Domain.Model.Orders.OrderLineItem, MemberSuite.Domain.Model, Version=1.0.0.21730, Culture=neutral, PublicKeyToken=null"&gt; &lt;property name="Total" type="System.Decimal, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"&gt; &lt;column name="Total" /&gt; &lt;/property&gt; &lt;/composite-element&gt; &lt;/list&gt; </code></pre> <p>You can see Orders has many OrderLineItems. Whenever I change any lineitem, NHibernate deletes all of the line items and reinserts them; over time, this causes pretty bad index fragmentation. I want to make NHibernate simply update the items that have changed.</p> <p>From what I've read, this is normal behavior for bags, because NH can't uniquely identify an entity in the bag. But for Lists, NHibernate <em>should</em> be able to do this via the List Index - but NH is still doing DELETE-INSERT. So my question is:</p> <p>What should the <strong>hbm</strong> look like for a list that makes NH behave properly?</p> <p>and...</p> <p>Is there a way to generate this HBM with the latest Fluent NHibernate?</p>
 

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