[GH-2201] Only check collections for duplicate joins.

Author: David Ellingsworth

src/NHibernate/Loader/Criteria/CriteriaJoinWalker.cs

@@ -208,7 +208,10 @@ protected override JoinType GetJoinType(IAssociationType type, FetchMode config,
 				case SelectMode.FetchLazyPropertyGroup:
 				case SelectMode.ChildFetch:
 				case SelectMode.JoinOnly:
-					IsDuplicateAssociation(lhsTable, lhsColumns, type); //deliberately ignore return value!
+					if (type.IsCollectionType)
+					{
+						IsDuplicateAssociation(lhsTable, lhsColumns, type); //deliberately ignore return value!
+					}
 					return GetJoinType(nullable, currentDepth);
 
 				case SelectMode.Skip:

src/NHibernate/Loader/JoinWalker.cs

@@ -605,9 +605,13 @@ protected virtual JoinType GetJoinType(IAssociationType type, FetchMode config,
 			if (IsTooDeep(currentDepth) || (type.IsCollectionType && IsTooManyCollections))
 				return JoinType.None;
 
-			bool dupe = IsDuplicateAssociation(lhsTable, lhsColumns, type);
-			if (dupe)
-				return JoinType.None;
+			if (type.IsCollectionType)
+			{
+				if(IsDuplicateAssociation(lhsTable, lhsColumns, type))
+				{
+					return JoinType.None;
+				}
+			}
 
 			return GetJoinType(nullable, currentDepth);
 		}
@@ -791,21 +795,6 @@ public override int GetHashCode()
 			}
 		}
 
-		/// <summary>
-		/// Should we join this association?
-		/// </summary>
-		protected bool IsJoinable(JoinType joinType, ISet<AssociationKey> visitedAssociationKeys, string lhsTable,
-			string[] lhsColumnNames, IAssociationType type, int depth)
-		{
-			if (joinType < JoinType.InnerJoin) return false;
-			if (joinType == JoinType.InnerJoin) return true;
-
-			int maxFetchDepth = Factory.Settings.MaximumFetchDepth;
-			bool tooDeep = maxFetchDepth >= 0 && depth >= maxFetchDepth;
-
-			return !tooDeep && !IsDuplicateAssociation(lhsTable, lhsColumnNames, type);
-		}
-
 		protected SqlString OrderBy(IList<OuterJoinableAssociation> associations, SqlString orderBy)
 		{
 			return MergeOrderings(OrderBy(associations), orderBy);