Remove excessive MapTransform and ConcatTransform usage from the IncludeProvider

Author: AlexUstinov

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.Include.cs

@@ -77,7 +77,7 @@ protected SqlExpression CreateIncludeViaComplexConditionExpression(
       IncludeProvider provider, Func<ParameterContext, object> valueAccessor,
       IList<SqlExpression> sourceColumns, out QueryParameterBinding binding)
     {
-      var filterTupleDescriptor = provider.FilteredColumnsExtractionTransform.Descriptor;
+      var filterTupleDescriptor = provider.FilteredTupleDescriptor;
       var mappings = filterTupleDescriptor.Select(type => Driver.GetTypeMapping(type));
       binding = new QueryRowFilterParameterBinding(mappings, valueAccessor);
       var resultExpression = SqlDml.DynamicFilter(binding);
@@ -89,7 +89,7 @@ protected SqlExpression CreateIncludeViaTemporaryTableExpression(
       IncludeProvider provider, IList<SqlExpression> sourceColumns,
       out TemporaryTableDescriptor tableDescriptor)
     {
-      var filterTupleDescriptor = provider.FilteredColumnsExtractionTransform.Descriptor;
+      var filterTupleDescriptor = provider.FilteredTupleDescriptor;
       var filteredColumns = provider.FilteredColumns.Select(index => sourceColumns[index]).ToList();
       tableDescriptor = DomainHandler.TemporaryTableManager
         .BuildDescriptor(Mapping, Guid.NewGuid().ToString(), filterTupleDescriptor);

Orm/Xtensive.Orm/Orm/Rse/Providers/Compilable/IncludeProvider.cs

@@ -13,7 +13,6 @@
 using Xtensive.Tuples;
 using Tuple = Xtensive.Tuples.Tuple;
 using Xtensive.Tuples.Transform;
-using System.Linq;
 using Xtensive.Reflection;
 
 namespace Xtensive.Orm.Rse.Providers
@@ -53,27 +52,26 @@ public sealed class IncludeProvider: UnaryProvider,
     /// </summary>
     public Expression<Func<ParameterContext, IEnumerable<Tuple>>> FilterDataSource { get; private set; }
 
-    public MapTransform FilteredColumnsExtractionTransform { get; private set; }
-
-    public ConcatTransform ResultTransform { get; private set; }
+    public TupleDescriptor FilteredTupleDescriptor { get; private set; }
 
     private static readonly TupleDescriptor BoolTupleDescriptor = TupleDescriptor.Create(new[] {WellKnownTypes.Bool});
 
     /// <inheritdoc/>
     protected override RecordSetHeader BuildHeader()
     {
-      var newHeader = Source.Header.Add(new SystemColumn(ResultColumnName, 0, WellKnownTypes.Bool));
+      return Source.Header.Add(new SystemColumn(ResultColumnName, 0, WellKnownTypes.Bool));
+    }
+
+    protected override void Initialize()
+    {
+      base.Initialize();
       var fieldTypes = new Type[FilteredColumns.Count];
       for (var index = 0; index < fieldTypes.Length; index++) {
-        fieldTypes[index] = newHeader.Columns[FilteredColumns[index]].Type;
+        fieldTypes[index] = Header.Columns[FilteredColumns[index]].Type;
       }
-      var tupleDescriptor = TupleDescriptor.Create(fieldTypes);
-      FilteredColumnsExtractionTransform = new MapTransform(true, tupleDescriptor, FilteredColumns);
-      ResultTransform = new ConcatTransform(true, Source.Header.TupleDescriptor, BoolTupleDescriptor);
-      return newHeader;
+      FilteredTupleDescriptor = TupleDescriptor.Create(fieldTypes);
     }
 
-
     // Constructors
 
     /// <summary>