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copied!<p>In your <strong>first query</strong>, LINQ to SQL knows it <strong><em>only</em></strong> needs to return a scalar value <code>GroupID</code> (or a <code>GroupID</code> array). So that's what it does: LINQ to SQL queries <em>only</em> that column in the database and returns only those value(s).</p> <pre><code>From g In Db.Context.Current.Groups Select g.GroupID </code></pre> <p>In your <strong>second query</strong>, LINQ to SQL knows it needs to return a scalar (same as the first query), <strong>plus the value returned by a property/method call on an actual entity instance</strong>, a Group object. So, to be able to call <code>MemberCount()</code> there must first be a Group object to call it on, right? So LINQ to SQL must do a full entity fetch, and that's why it's querying all the columns.</p> <pre><code>From g In Db.Context.Current.Groups Select g.GroupID, g.MemberCount 'property/method call on an entity </code></pre> <p>[Just theorizing here...] You might say, But <code>MemberCount()</code> doesn't need a full entity fetch, it doesn't need all that data - all it needs is <code>GroupID</code>. And I would reply, How does LINQ to SQL know that? How can LINQ to SQL know that your method <code>MemberCount()</code> <em>doesn't</em> rely on the data of other db-column-based properties? It can't know that, so it must return the full object. [End theorizing.]</p> <p><strong>Suggestion:</strong> Join <code>ContactsGroupsXtabs</code> in your second query, group on <code>GroupID</code> and do a <code>Count()</code> on the group to get your value. (I can see by your other SO questions and answers that you know how to do all that so I'll skip the example.)</p>

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