Query: Avoid binding to parent QMV if projection is client side produ…

…cing N+1 queries

src/Microsoft.EntityFrameworkCore.Relational/Query/ExpressionVisitors/SqlTranslatingExpressionVisitor.cs

@@ -716,7 +716,7 @@ var selectExpression
             RelationalQueryModelVisitor queryModelVisitor,
             Func<RelationalQueryModelVisitor, AliasExpression> binder)
         {
-            if (queryModelVisitor == null)
+            if (queryModelVisitor == null || queryModelVisitor.RequiresClientProjection)
             {
                 return null;
             }

src/Microsoft.EntityFrameworkCore.Specification.Tests/QueryTestBase.cs

@@ -57,7 +57,7 @@ public virtual void Method_with_constant_queryable_arg()
             }
         }
 
-        private static IQueryable<Customer> QueryableArgQuery(NorthwindContext context, IQueryable<string> ids) 
+        private static IQueryable<Customer> QueryableArgQuery(NorthwindContext context, IQueryable<string> ids)
             => context.Customers.Where(c => ids.Contains(c.CustomerID));
 
         [ConditionalFact]
@@ -2183,6 +2183,27 @@ var efObjects
                     });
         }
 
+        [ConditionalFact]
+        public virtual void Select_nested_collection_multi_level()
+        {
+            using (var context = CreateContext())
+            {
+                var customers = context.Customers
+                    .Where(c => c.CustomerID.StartsWith("A"))
+                    .Select(c => new
+                    {
+                        Orders = c.Orders
+                            .Where(o => o.OrderID < 10500)
+                            .Take(3)
+                            .Select(o => new { Date = o.OrderDate })
+                    })
+                    .ToList();
+
+                Assert.Equal(4, customers.Count);
+                Assert.All(customers, t => Assert.True(t.Orders.Count() <= 3));
+            }
+        }
+
         [ConditionalFact]
         public virtual void Select_correlated_subquery_projection()
         {

test/Microsoft.EntityFrameworkCore.SqlServer.FunctionalTests/QueryNavigationsSqlServerTest.cs

@@ -576,17 +576,17 @@ public override void Collection_select_nav_prop_all_client()
 FROM [Customers] AS [c]
 ORDER BY [c].[CustomerID]
 
-@_outer_CustomerID: ALFKI (Size = 450)
+@_outer_CustomerID1: ALFKI (Size = 450)
 
 SELECT [o1].[OrderID], [o1].[CustomerID], [o1].[EmployeeID], [o1].[OrderDate]
 FROM [Orders] AS [o1]
-WHERE @_outer_CustomerID = [o1].[CustomerID]
+WHERE @_outer_CustomerID1 = [o1].[CustomerID]
 
-@_outer_CustomerID: ANATR (Size = 450)
+@_outer_CustomerID1: ANATR (Size = 450)
 
 SELECT [o1].[OrderID], [o1].[CustomerID], [o1].[EmployeeID], [o1].[OrderDate]
 FROM [Orders] AS [o1]
-WHERE @_outer_CustomerID = [o1].[CustomerID]",
+WHERE @_outer_CustomerID1 = [o1].[CustomerID]",
                 Sql);
         }
 

test/Microsoft.EntityFrameworkCore.SqlServer.FunctionalTests/QuerySqlServerTest.cs

@@ -596,23 +596,23 @@ public override void Let_any_subquery_anonymous()
 FROM [Customers] AS [c]
 ORDER BY [c].[CustomerID]
 
-@_outer_CustomerID: ALFKI (Size = 450)
+@_outer_CustomerID1: ALFKI (Size = 450)
 
 SELECT CASE
     WHEN EXISTS (
         SELECT 1
         FROM [Orders] AS [o1]
-        WHERE [o1].[CustomerID] = @_outer_CustomerID)
+        WHERE [o1].[CustomerID] = @_outer_CustomerID1)
     THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT)
 END
 
-@_outer_CustomerID: ANATR (Size = 450)
+@_outer_CustomerID1: ANATR (Size = 450)
 
 SELECT CASE
     WHEN EXISTS (
         SELECT 1
         FROM [Orders] AS [o1]
-        WHERE [o1].[CustomerID] = @_outer_CustomerID)
+        WHERE [o1].[CustomerID] = @_outer_CustomerID1)
     THEN CAST(1 AS BIT) ELSE CAST(0 AS BIT)
 END",
                 Sql);
@@ -5282,6 +5282,20 @@ public override void Select_nested_collection()
                 Sql);
         }
 
+        public override void Select_nested_collection_multi_level()
+        {
+            base.Select_nested_collection_multi_level();
+
+            Assert.StartsWith(@"SELECT [c].[CustomerID]
+FROM [Customers] AS [c]
+WHERE [c].[CustomerID] LIKE N'A' + N'%' AND (CHARINDEX(N'A', [c].[CustomerID]) = 1)
+
+SELECT [o].[CustomerID], [o].[OrderDate]
+FROM [Orders] AS [o]
+WHERE [o].[OrderID] < 10500",
+                Sql);
+        }
+
         public override void Select_correlated_subquery_projection()
         {
             base.Select_correlated_subquery_projection();