Optimize BuildTypedQuery() (#432)

* Optimize `BuildTypedQuery()`

* fix inserting to the end

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Providers/SqlCompiler.Index.cs

@@ -4,14 +4,6 @@
 // Created by: Denis Krjuchkov
 // Created:    2009.11.13
 
-using System;
-using System.Collections.Concurrent;
-using System.Collections.Generic;
-using System.Linq;
-using System.Linq.Expressions;
-using Xtensive.Core;
-using Xtensive.Linq;
-using Xtensive.Orm.Internals;
 using Xtensive.Orm.Model;
 using Xtensive.Orm.Rse.Providers;
 using Xtensive.Reflection;
@@ -24,22 +16,7 @@ namespace Xtensive.Orm.Providers
 {
   public partial class SqlCompiler
   {
-    protected readonly struct QueryAndBindings
-    {
-      public SqlSelect Query { get; }
-      public List<QueryParameterBinding> Bindings { get; }
-
-      public QueryAndBindings(SqlSelect initialQuery)
-      {
-        Query = initialQuery;
-        Bindings = new List<QueryParameterBinding>();
-      }
-      public QueryAndBindings(SqlSelect initialQuery, List<QueryParameterBinding> bindings)
-      {
-        Query = initialQuery;
-        Bindings = bindings;
-      }
-    }
+    protected record struct QueryAndBindings(SqlSelect Query, List<QueryParameterBinding> Bindings);
 
     private TypeMapping int32TypeMapping;
 
@@ -54,17 +31,13 @@ internal protected override SqlProvider VisitIndex(IndexProvider provider)
     protected QueryAndBindings BuildProviderQuery(IndexInfo index)
     {
       if (index.IsVirtual) {
-        if ((index.Attributes & IndexAttributes.Union) > 0)
-          return BuildUnionQuery(index);
-        if ((index.Attributes & IndexAttributes.Join) > 0)
-          return BuildJoinQuery(index);
-        if ((index.Attributes & IndexAttributes.Filtered) > 0)
-          return BuildFilteredQuery(index);
-        if ((index.Attributes & IndexAttributes.View) > 0)
-          return BuildViewQuery(index);
-        if ((index.Attributes & IndexAttributes.Typed) > 0)
-          return BuildTypedQuery(index);
-        throw new NotSupportedException(String.Format(Strings.ExUnsupportedIndex, index.Name, index.Attributes));
+        var attrs = index.Attributes;
+        return (attrs & IndexAttributes.Union) > 0 ? BuildUnionQuery(index)
+          : (attrs & IndexAttributes.Join) > 0 ? BuildJoinQuery(index)
+          : (attrs & IndexAttributes.Filtered) > 0 ? BuildFilteredQuery(index)
+          : (attrs & IndexAttributes.View) > 0 ? BuildViewQuery(index)
+          : (attrs & IndexAttributes.Typed) > 0 ? BuildTypedQuery(index)
+          : throw new NotSupportedException(String.Format(Strings.ExUnsupportedIndex, index.Name, index.Attributes));
       }
       return BuildTableQuery(index);
     }
@@ -98,7 +71,7 @@ private QueryAndBindings BuildTableQuery(IndexInfo index)
           queryColumns.Add(tableRef[lookup[c.Field]]);
         }
       }
-      return new QueryAndBindings(query);
+      return new QueryAndBindings(query, []);
     }
 
     private QueryAndBindings BuildUnionQuery(IndexInfo index)
@@ -285,10 +258,9 @@ private QueryAndBindings BuildTypedQuery(IndexInfo index)
       var baseQueryAndBindings = BuildProviderQuery(underlyingIndex);
       var baseQuery = baseQueryAndBindings.Query;
       var bindings = baseQueryAndBindings.Bindings;
-      var query = SqlDml.Select(baseQuery.From);
+      var query = SqlDml.Select(baseQuery.From, baseQuery.Columns.Count + 1);
       query.Where = baseQuery.Where;
 
-      var baseColumns = baseQuery.Columns.ToList();
       var typeIdColumnIndex = index.Columns
         .Select((c, i) => (c.Field, i))
         .Single(p => p.Field.IsTypeId && p.Field.IsSystem).i;
@@ -332,8 +304,19 @@ private QueryAndBindings BuildTypedQuery(IndexInfo index)
       }
 
       var typeIdColumnRef = SqlDml.ColumnRef(typeIdColumn, WellKnown.TypeIdFieldName);
-      baseColumns.Insert(typeIdColumnIndex, typeIdColumnRef);
-      query.Columns.AddRange(baseColumns);
+      var queryColumns = query.Columns;
+      bool inserted = false;
+      int i = 0;
+      foreach (var column in baseQuery.Columns) {
+        if (i++ == typeIdColumnIndex) {
+          queryColumns.Add(typeIdColumnRef);
+          inserted = true;
+        }
+        queryColumns.Add(column);
+      }
+      if (!inserted) {
+        queryColumns.Add(typeIdColumnRef);
+      }
 
       return new QueryAndBindings(query, bindings);
     }

Orm/Xtensive.Orm/Sql/Dml/Collections/SqlColumnCollection.cs

@@ -65,6 +65,7 @@ public void Insert(int index, SqlExpression expression, string alias) =>
     /// Initializes new instance of this type.
     /// </summary>
     public SqlColumnCollection() { }
+    public SqlColumnCollection(int capacity) : base(capacity) { }
 
     /// <summary>
     /// Initializes new instance of this type.

Orm/Xtensive.Orm/Sql/Dml/Statements/SqlSelect.cs

@@ -17,7 +17,7 @@ public class SqlSelect
       ISqlQueryExpression
   {
     private readonly SqlUserColumn asterisk = SqlDml.Column(SqlDml.Asterisk);
-    private readonly SqlColumnCollection columns = new();
+    private readonly SqlColumnCollection columns;
     private SqlLockType _lock;
     private SqlColumnCollection groupBy;
     private SqlExpression having;
@@ -256,15 +256,16 @@ IEnumerator IEnumerable.GetEnumerator()
 
     // Constructors
 
-    internal SqlSelect(SqlTable from)
-      : this()
+    internal SqlSelect(SqlTable from, int? capacity = null)
+      : this(capacity ?? from.Columns.Count)
     {
       From = from;
     }
 
-    internal SqlSelect()
+    internal SqlSelect(int? capacity = null)
       : base(SqlNodeType.Select)
     {
+      columns = capacity.HasValue ? new(capacity.Value) : new();
     }
   }
 }

Orm/Xtensive.Orm/Sql/SqlDml.cs

@@ -1691,10 +1691,10 @@ public static SqlSelect Select(SqlExpression expression)
       return result;
     }
 
-    public static SqlSelect Select(SqlTable table)
+    public static SqlSelect Select(SqlTable table, int? capacity = null)
     {
       ArgumentNullException.ThrowIfNull(table);
-      return new SqlSelect(table);
+      return new SqlSelect(table, capacity);
     }
 
     #endregion