string.Intern is applied to command texts only if domain uses parameters for type identifiers

this reduces number of string variations

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/Providers/StorageDriver.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2009-2022 Xtensive LLC.
+// Copyright (C) 2009-2025 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Denis Krjuchkov
@@ -84,6 +84,7 @@ public SqlCompilationResult Compile(ISqlCompileUnit statement)
       var options = new SqlCompilerConfiguration {
         DatabaseQualifiedObjects = configuration.IsMultidatabase,
         CommentLocation = configuration.TagsLocation.ToCommentLocation(),
+        TypeIndentifiersAsParameters = configuration.PreferTypeIdsAsQueryParameters
       };
       return underlyingDriver.Compile(statement, options);
     }

Orm/Xtensive.Orm/Sql/Compiler/SqlCompilationResult.cs

@@ -1,6 +1,6 @@
 // Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 
 using System;
 using System.Collections.Generic;
@@ -15,6 +15,7 @@ public sealed class SqlCompilationResult
     private readonly IReadOnlyList<Node> resultNodes;
     private readonly string resultText;
     private readonly IDictionary<object, string> parameterNames;
+    private readonly bool internCommandResult;
     private volatile int lastResultLength;
 
     /// <inheritdoc/>
@@ -59,16 +60,18 @@ public string GetCommandText()
     public string GetCommandText(SqlPostCompilerConfiguration configuration)
     {
       if (resultText!=null)
-        return string.Intern(resultText);
-      string result = string.Intern(PostCompiler.Process(resultNodes, configuration, lastResultLength));
+        return (internCommandResult) ? string.Intern(resultText) : resultText;
+      string result = PostCompiler.Process(resultNodes, configuration, lastResultLength);
+      if (internCommandResult)
+        result = string.Intern(result);
       lastResultLength = result.Length;
       return result;
     }
 
 
     // Constructors
 
-    internal SqlCompilationResult(IReadOnlyList<Node> result, IDictionary<object, string> parameterNames)
+    internal SqlCompilationResult(IReadOnlyList<Node> result, IDictionary<object, string> parameterNames, bool internCommandResult = false)
     {
       switch (result.Count) {
         case 0:
@@ -82,6 +85,7 @@ internal SqlCompilationResult(IReadOnlyList<Node> result, IDictionary<object, st
           break;
       }
       this.parameterNames = parameterNames.Count > 0 ? parameterNames : null;
+      this.internCommandResult = internCommandResult;
     }
   }
 }

Orm/Xtensive.Orm/Sql/Compiler/SqlCompiler.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2008-2021 Xtensive LLC.
+// Copyright (C) 2008-2025 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 
@@ -43,7 +43,7 @@ public SqlCompilationResult Compile(ISqlCompileUnit unit, SqlCompilerConfigurati
       configuration = compilerConfiguration;
       context = new SqlCompilerContext(configuration);
       unit.AcceptVisitor(this);
-      return new SqlCompilationResult(context.Output.Children, context.ParameterNameProvider.NameTable);
+      return new SqlCompilationResult(context.Output.Children, context.ParameterNameProvider.NameTable, compilerConfiguration.TypeIndentifiersAsParameters);
     }
 
     #region Visitors

Orm/Xtensive.Orm/Sql/Compiler/SqlCompilerConfiguration.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2009-2022 Xtensive LLC.
+// Copyright (C) 2009-2025 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Denis Krjuchkov
@@ -35,6 +35,11 @@ public sealed class SqlCompilerConfiguration
     /// </summary>
     public SqlCommentLocation CommentLocation { get; set; } = SqlCommentLocation.Nowhere;
 
+    /// <summary>
+    /// Type identifiers presented as parameters instead of constant values.
+    /// </summary>
+    public bool TypeIndentifiersAsParameters { get; set; }
+
     /// <summary>
     /// Clones this instance.
     /// </summary>
@@ -44,6 +49,7 @@ public SqlCompilerConfiguration Clone()
       return new SqlCompilerConfiguration {
         ParameterNamePrefix = ParameterNamePrefix,
         DatabaseQualifiedObjects = DatabaseQualifiedObjects,
+        TypeIndentifiersAsParameters = TypeIndentifiersAsParameters,
       };
     }
   }