title: How to convert Linq.ParallelQuery to Linq.IQueryable
body: <pre><code>var transactions = from t in context.Transactions
                                 group t.Create_Date_Time by t.Participation_Id
                                     into t1
                                     select new { ParticipationId = t1.Key, CreateDateTime = t1.Max() };
  
              var cases = from c in context.Cases
                          group c.Create_Date_Time by c.Participation_Id
                              into c1
                              select new { ParticipationId = c1.Key, CreateDateTime = c1.Max() };
  
              var interactions = (from i in context.Interactions
                                 join pp in context.Party_Participation on i.Party_Id equals pp.Party_Id
                                 group i.Last_Update_Date_Time.HasValue ? i.Last_Update_Date_Time : i.Create_Date_Time by
                                     pp.Participation_Id
                                 into i1
                                 select new {ParticipationId = i1.Key, CreateDateTime = i1.Max()}).AsQueryable();
  </code></pre>
  
  <p>Considering the above code, following will work</p>
  
  <pre><code>transactions.Union(cases);
  </code></pre>
  
  <p>However following will not work</p>
  
  <pre><code>transactions.Union(interactions);
  </code></pre>
  
  <p>Because transactions and cases both are returning <code>Linq.IQueryable</code> but the last one is <code>Linq.ParallelQuery</code> due to it join with an another table.</p>
  
  <p>I need this functionality basically to make Union. <code>interactions.Union(transactions)</code> or  <code>transactions.Union(interactions)</code> one with other.</p>