Adjustment for Join-fetching with property-ref results in n+1 select

Author: fredericDelaporte

src/NHibernate/Async/Loader/Loader.cs

@@ -651,28 +651,7 @@ private async Task InstanceAlreadyLoadedAsync(DbDataReader rs, int i, IEntityPer
 				}
 			}
 
-			// #1226: If it is already loaded and can be loaded from an association with a property ref, make
-			// sure it is also cached by its unique key.
-			var ukName = OwnerAssociationTypes?[i]?.RHSUniqueKeyPropertyName;
-			if (ukName == null)
-				return;
-			var index = ((IUniqueKeyLoadable) persister).GetPropertyIndex(ukName);
-			var ukValue = persister.GetPropertyValue(obj, index);
-			// ukValue can be null for two reasons:
-			//  - Entity currently loading and not yet fully hydrated. In such case, it has already been handled by
-			//    InstanceNotYetLoaded on a previous row, there is nothing more to do. This case could also be
-			//    detected with "session.PersistenceContext.GetEntry(obj).Status == Status.Loading", but since there
-			//    is a second case, just test for ukValue null.
-			//  - Entity association is unset in session but not yet persisted, autoflush disabled: ignore. We are
-			//    already in an error case: querying entities changed in session without flushing them before querying.
-			//    So here it gets loaded as if it were still associated, but we do not have the key anymore in session:
-			//    we cannot cache it, so long for the additionnal round-trip this will cause. (Do not fallback on
-			//    reading the key in rs, this is stale data in regard to the session state.)
-			if (ukValue == null)
-				return;
-			var type = persister.PropertyTypes[index];
-			var euk = new EntityUniqueKey(persister.EntityName, ukName, ukValue, type, session.Factory);
-			session.PersistenceContext.AddEntity(euk, obj);
+			CacheByUniqueKey(i, persister, obj, session);
 		}
 
 		/// <summary>

src/NHibernate/Loader/Loader.cs

@@ -973,12 +973,17 @@ private void InstanceAlreadyLoaded(DbDataReader rs, int i, IEntityPersister pers
 				}
 			}
 
+			CacheByUniqueKey(i, persister, obj, session);
+		}
+
+		private void CacheByUniqueKey(int i, IEntityPersister persister, object obj, ISessionImplementor session)
+		{
 			// #1226: If it is already loaded and can be loaded from an association with a property ref, make
 			// sure it is also cached by its unique key.
 			var ukName = OwnerAssociationTypes?[i]?.RHSUniqueKeyPropertyName;
 			if (ukName == null)
 				return;
-			var index = ((IUniqueKeyLoadable) persister).GetPropertyIndex(ukName);
+			var index = ((IUniqueKeyLoadable)persister).GetPropertyIndex(ukName);
 			var ukValue = persister.GetPropertyValue(obj, index);
 			// ukValue can be null for two reasons:
 			//  - Entity currently loading and not yet fully hydrated. In such case, it has already been handled by