From ad708b716e293ed5fe17efd0d023a4efef3f8a8a Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Fri, 4 Feb 2022 19:08:13 +0500
Subject: [PATCH 01/14] Ignore tests for mysql

---
 Orm/Xtensive.Orm.Tests/Linq/TagTest.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Orm/Xtensive.Orm.Tests/Linq/TagTest.cs b/Orm/Xtensive.Orm.Tests/Linq/TagTest.cs
index f53175a6bd..a8ca49b994 100644
--- a/Orm/Xtensive.Orm.Tests/Linq/TagTest.cs
+++ b/Orm/Xtensive.Orm.Tests/Linq/TagTest.cs
@@ -662,8 +662,9 @@ void SqlCapturer(object sender, DbCommandEventArgs args)
     [Test]
     public void SessionTagSingle()
     {
-      var allCommands = new List<string>();
+      Require.ProviderIsNot(StorageProvider.MySql);
 
+      var allCommands = new List<string>();
       var id = 0L;
 
       using (var populateSession = Domain.OpenSession())
@@ -735,6 +736,8 @@ void SqlCapturer(object sender, DbCommandEventArgs args)
     [Test]
     public void SessionTagSingleOrDefault()
     {
+      Require.ProviderIsNot(StorageProvider.MySql);
+
       var allCommands = new List<string>();
       var id = 0L;
 
@@ -806,6 +809,7 @@ void SqlCapturer(object sender, DbCommandEventArgs args)
     [Test]
     public void SessionTagPrefetchEntity()
     {
+      Require.ProviderIsNot(StorageProvider.MySql);
       var allCommands = new List<string>();
 
       using (var populateSession = Domain.OpenSession())

From f33b11b58f911ce0d84ccacf0ca040218b4b28e5 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Mon, 7 Feb 2022 18:41:14 +0500
Subject: [PATCH 02/14] MySql v5.7 and v8.0 drivers

Also several incompatibilities fixed:
- UNION operation was broken for some cases due to lack of round brackets so they were added, it seems to be compatible with v5.5 and v5.6;
- auto_increment value info in INFORMATION_SCHEMA happened to be different for v8.0, if no value generated it returns NULL. Since v5.7 and older versions
automatically inserts 1 as start value for just created table with auto-increment, NULLs were treated as 1. Since v5.7 and older always return value the changes
should work with them too.
---
 .../Sql.Drivers.MySql/DriverFactory.cs        |  6 +-
 .../Sql.Drivers.MySql/v5_0/Compiler.cs        |  6 +-
 .../Sql.Drivers.MySql/v5_0/Extractor.cs       | 71 ++++++-------------
 .../Sql.Drivers.MySql/v5_7/Compiler.cs        | 18 +++++
 .../Sql.Drivers.MySql/v5_7/Driver.cs          | 46 ++++++++++++
 .../Sql.Drivers.MySql/v5_7/Extractor.cs       | 18 +++++
 .../v5_7/ServerInfoProvider.cs                | 18 +++++
 .../Sql.Drivers.MySql/v5_7/Translator.cs      | 37 ++++++++++
 .../Sql.Drivers.MySql/v5_7/TypeMapper.cs      | 18 +++++
 .../Sql.Drivers.MySql/v8_0/Compiler.cs        | 18 +++++
 .../Sql.Drivers.MySql/v8_0/Driver.cs          | 46 ++++++++++++
 .../Sql.Drivers.MySql/v8_0/Extractor.cs       | 18 +++++
 .../v8_0/ServerInfoProvider.cs                | 18 +++++
 .../Sql.Drivers.MySql/v8_0/Translator.cs      | 37 ++++++++++
 .../Sql.Drivers.MySql/v8_0/TypeMapper.cs      | 18 +++++
 15 files changed, 339 insertions(+), 54 deletions(-)
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Driver.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Extractor.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/ServerInfoProvider.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Translator.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/TypeMapper.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Driver.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Extractor.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/ServerInfoProvider.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
 create mode 100644 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/TypeMapper.cs

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
index dd3c5e24c4..db4c3343fa 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
@@ -122,7 +122,11 @@ private static SqlDriver CreateDriverInstance(string connectionString, Version v
         5 when version.Minor == 1 => new v5_1.Driver(coreServerInfo),
         5 when version.Minor == 5 => new v5_5.Driver(coreServerInfo),
         5 when version.Minor == 6 => new v5_6.Driver(coreServerInfo),
-        _ => new v5_6.Driver(coreServerInfo)
+        5 when version.Major == 7 => new v5_7.Driver(coreServerInfo),
+        6 => throw new NotSupportedException(),
+        7 => throw new NotSupportedException(),
+        8 => new v8_0.Driver(coreServerInfo),
+        _ => new v8_0.Driver(coreServerInfo)
       };
     }
 
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
index 9b1ca2bfc0..27290279dd 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2021 Xtensive LLC.
+// Copyright (C) 2011-2022 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Malisa Ncube
@@ -124,8 +124,8 @@ protected virtual SqlExpression DateTimeAddInterval(SqlExpression date, SqlExpre
     public override void Visit(SqlQueryExpression node)
     {
       using (context.EnterScope(node)) {
-        bool needOpeningParenthesis = false;
-        bool needClosingParenthesis = false;
+        var needOpeningParenthesis = node.NodeType == SqlNodeType.Union;
+        var needClosingParenthesis = needOpeningParenthesis;
         context.Output.AppendText(translator.Translate(context, node, QueryExpressionSection.Entry));
         if (needOpeningParenthesis)
           context.Output.AppendText("(");
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs
index e908319bd3..4a4a2aa5ae 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2020 Xtensive LLC.
+// Copyright (C) 2011-2022 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Malisa Ncube
@@ -400,7 +400,7 @@ private static void ReadTableData(DbDataReader reader, Catalog catalog)
       var schemaName = reader.GetString(0);
       var schema = catalog.Schemas[schemaName];
       var tableName = reader.GetString(1);
-      schema.CreateTable(tableName);
+      _ = schema.CreateTable(tableName);
     }
 
     // ---- ReadTableColumnData
@@ -451,8 +451,8 @@ private void ReadTableColumnData(DbDataReader reader, ref ColumnReaderState<Tabl
       }
 
       // AutoIncrement
-      if (ReadAutoIncrement(reader, 13)) {
-        column.SequenceDescriptor = new SequenceDescriptor(column, ReadInt(reader, 14), 1);
+      if (ReadIfAutoIncrement(reader, 13)) {
+        column.SequenceDescriptor = new SequenceDescriptor(column, ReadAutoIncrementValue(reader, 14), 1);
       }
 
       //Column number.
@@ -468,12 +468,9 @@ private static void ReadViewData(DbDataReader reader, Catalog catalog)
       var schema = catalog.Schemas[reader.GetString(0)];
       var view = reader.GetString(1);
       var definition = ReadStringOrNull(reader, 2);
-      if (string.IsNullOrEmpty(definition)) {
-        schema.CreateView(view);
-      }
-      else {
-        schema.CreateView(view, SqlDml.Native(definition));
-      }
+      _ = string.IsNullOrEmpty(definition)
+        ? schema.CreateView(view)
+        : schema.CreateView(view, SqlDml.Native(definition));
     }
 
     //---- ReadViewColumnData
@@ -490,7 +487,7 @@ private static void ReadViewColumnData(DbDataReader reader, ref ColumnReaderStat
         state.Owner = schema.Views[reader.GetString(1)];
       }
 
-      state.Owner.CreateColumn(reader.GetString(2));
+      _ = state.Owner.CreateColumn(reader.GetString(2));
       state.LastColumnIndex = columnIndex;
     }
 
@@ -512,7 +509,7 @@ private static void ReadIndexColumnData(DbDataReader reader, ref IndexColumnRead
         var schema = state.Catalog.Schemas[reader.GetString(0)];
         state.Table = schema.Tables[reader.GetString(1)];
         if (IsFullTextIndex(reader, 4)) {
-          state.Table.CreateFullTextIndex(reader.GetString(2));
+          _ = state.Table.CreateFullTextIndex(reader.GetString(2));
         }
         else {
           state.Index = state.Table.CreateIndex(reader.GetString(2));
@@ -521,7 +518,7 @@ private static void ReadIndexColumnData(DbDataReader reader, ref IndexColumnRead
       }
 
       var column = state.Table.TableColumns[reader.GetString(6)];
-      state.Index.CreateIndexColumn(column);
+      _ = state.Index.CreateIndexColumn(column);
 
       state.LastColumnIndex = columnIndex;
     }
@@ -710,47 +707,21 @@ private static void CreateIndexBasedConstraint(ref IndexBasedConstraintReaderSta
     private static bool ReadBool(IDataRecord row, int index)
     {
       var value = row.GetString(index);
-      switch (value) {
-        case "Y":
-        case "YES":
-        case "ENABLED":
-        case "UNIQUE":
-          return true;
-        case "N":
-        case "NO":
-        case "DISABLED":
-        case "NONUNIQUE":
-          return false;
-        default:
-          throw new ArgumentOutOfRangeException(string.Format(Strings.ExInvalidBooleanStringX, value));
-      }
+      return value switch {
+        "Y" or "YES" or "ENABLED" or "UNIQUE" => true,
+        "N" or "NO" or "DISABLED" or "NONUNIQUE" => false,
+        _ => throw new ArgumentOutOfRangeException(string.Format(Strings.ExInvalidBooleanStringX, value)),
+      };
     }
 
-    private static bool IsFullTextIndex(IDataRecord row, int index)
-    {
-      var value = ReadStringOrNull(row, index);
-      if (!string.IsNullOrEmpty(value)) {
-        value = value.ToUpperInvariant();
-        return value == "FULLTEXT";
-      }
-      return false;
-    }
+    private static bool IsFullTextIndex(IDataRecord row, int index) =>
+      ReadStringOrNull(row, index).Equals("FULLTEXT", StringComparison.OrdinalIgnoreCase);
 
-    private static bool ReadAutoIncrement(IDataRecord row, int index)
-    {
-      var value = ReadStringOrNull(row, index);
-      if (!string.IsNullOrEmpty(value)) {
-        value = value.ToUpperInvariant();
-        return value == "AUTO_INCREMENT";
-      }
-      return false;
-    }
+    private static bool ReadIfAutoIncrement(IDataRecord row, int index) =>
+      ReadStringOrNull(row, index).Equals("AUTO_INCREMENT", StringComparison.OrdinalIgnoreCase);
 
-    private static long ReadLong(IDataRecord row, int index)
-    {
-      var value = row.GetDecimal(index);
-      return value > long.MaxValue ? long.MaxValue : (long) value;
-    }
+    private static int ReadAutoIncrementValue(IDataRecord row, int index) =>
+      row.IsDBNull(index) ? 1 : ReadInt(row, index);
 
     private static int ReadInt(IDataRecord row, int index)
     {
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
new file mode 100644
index 0000000000..b12423abd2
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class Compiler : v5_6.Compiler
+  {
+    // Constructors
+
+    public Compiler(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Driver.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Driver.cs
new file mode 100644
index 0000000000..7719d0cafd
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Driver.cs
@@ -0,0 +1,46 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Info;
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class Driver : MySql.Driver
+  {
+    protected override Sql.TypeMapper CreateTypeMapper()
+    {
+      return new TypeMapper(this);
+    }
+
+    protected override SqlCompiler CreateCompiler()
+    {
+      return new Compiler(this);
+    }
+
+    protected override SqlTranslator CreateTranslator()
+    {
+      return new Translator(this);
+    }
+
+    protected override Model.Extractor CreateExtractor()
+    {
+      return new Extractor(this);
+    }
+
+    protected override Info.ServerInfoProvider CreateServerInfoProvider()
+    {
+      return new ServerInfoProvider(this);
+    }
+
+    // Constructors
+
+    public Driver(CoreServerInfo coreServerInfo)
+      : base(coreServerInfo)
+    {
+    }
+  }
+}
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Extractor.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Extractor.cs
new file mode 100644
index 0000000000..512dd5e064
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Extractor.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class Extractor : v5_6.Extractor
+  {
+    // Constructors
+
+    public Extractor(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/ServerInfoProvider.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/ServerInfoProvider.cs
new file mode 100644
index 0000000000..7e1b076b64
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/ServerInfoProvider.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class ServerInfoProvider : v5_6.ServerInfoProvider
+  {
+    // Constructors
+
+    public ServerInfoProvider(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Translator.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Translator.cs
new file mode 100644
index 0000000000..346a61a098
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Translator.cs
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+using System;
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Dml;
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class Translator : v5_6.Translator
+  {
+    /// <inheritdoc/>
+    public override string Translate(SqlCompilerContext context, SqlCast node, NodeSection section)
+    {
+      if (node.Type.Type==SqlType.DateTime)
+        switch (section) {
+        case NodeSection.Entry:
+          return "CAST(";
+        case NodeSection.Exit:
+          return "AS " + Translate(node.Type) + "(6))";
+        default:
+          throw new ArgumentOutOfRangeException("section");
+        }
+      return base.Translate(context, node, section);
+    }
+
+    // Constructors
+
+    public Translator(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/TypeMapper.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/TypeMapper.cs
new file mode 100644
index 0000000000..2a0d6f655a
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/TypeMapper.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v5_7
+{
+  internal class TypeMapper : v5_6.TypeMapper
+  {
+    // Constructors
+
+    public TypeMapper(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
new file mode 100644
index 0000000000..5fc7f46b43
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class Compiler : v5_7.Compiler
+  {
+    // Constructors
+
+    public Compiler(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Driver.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Driver.cs
new file mode 100644
index 0000000000..4e508f6309
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Driver.cs
@@ -0,0 +1,46 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Info;
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class Driver : MySql.Driver
+  {
+    protected override Sql.TypeMapper CreateTypeMapper()
+    {
+      return new TypeMapper(this);
+    }
+
+    protected override SqlCompiler CreateCompiler()
+    {
+      return new Compiler(this);
+    }
+
+    protected override SqlTranslator CreateTranslator()
+    {
+      return new Translator(this);
+    }
+
+    protected override Model.Extractor CreateExtractor()
+    {
+      return new Extractor(this);
+    }
+
+    protected override Info.ServerInfoProvider CreateServerInfoProvider()
+    {
+      return new ServerInfoProvider(this);
+    }
+
+    // Constructors
+
+    public Driver(CoreServerInfo coreServerInfo)
+      : base(coreServerInfo)
+    {
+    }
+  }
+}
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Extractor.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Extractor.cs
new file mode 100644
index 0000000000..9c34206d51
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Extractor.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class Extractor : v5_7.Extractor
+  {
+    // Constructors
+
+    public Extractor(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/ServerInfoProvider.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/ServerInfoProvider.cs
new file mode 100644
index 0000000000..ddc9d1f1ab
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/ServerInfoProvider.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class ServerInfoProvider : v5_7.ServerInfoProvider
+  {
+    // Constructors
+
+    public ServerInfoProvider(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
new file mode 100644
index 0000000000..ecea47bab2
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
@@ -0,0 +1,37 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+using System;
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Dml;
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class Translator : v5_7.Translator
+  {
+    /// <inheritdoc/>
+    public override string Translate(SqlCompilerContext context, SqlCast node, NodeSection section)
+    {
+      if (node.Type.Type==SqlType.DateTime)
+        switch (section) {
+        case NodeSection.Entry:
+          return "CAST(";
+        case NodeSection.Exit:
+          return "AS " + Translate(node.Type) + "(6))";
+        default:
+          throw new ArgumentOutOfRangeException("section");
+        }
+      return base.Translate(context, node, section);
+    }
+
+    // Constructors
+
+    public Translator(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/TypeMapper.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/TypeMapper.cs
new file mode 100644
index 0000000000..ce4bb1815a
--- /dev/null
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/TypeMapper.cs
@@ -0,0 +1,18 @@
+// Copyright (C) 2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+// Created by: Alexey Kulakov
+// Created:    2022.02.03
+
+namespace Xtensive.Sql.Drivers.MySql.v8_0
+{
+  internal class TypeMapper : v5_7.TypeMapper
+  {
+    // Constructors
+
+    public TypeMapper(SqlDriver driver)
+      : base(driver)
+    {
+    }
+  }
+}

From 03e7b07301c56b2b10499285d4da34d6c540b4b4 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 9 Feb 2022 18:41:11 +0500
Subject: [PATCH 03/14] Update MySQL supported versions

---
 ReadMe.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ReadMe.md b/ReadMe.md
index 5d50d06e25..51a3c362c9 100644
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -7,7 +7,7 @@ Supported databases:
 - MS Azure SQL Database
 - Oracle 10g, 11g
 - PostgreSQL 8.3, 8.4, 9.0, 9.1, 9.2, 10, 11
-- MySQL 5.5, 5.6
+- MySQL 5.5, 5.6, 5.7, 8.0
 - Firebird 2.5
 - Sqlite 3
 

From 4f8a30e7f4ec37e859bd64edf7f0213842d495f6 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 1 Jun 2022 17:37:22 +0500
Subject: [PATCH 04/14] Removed copy of cast translation + Fixed Set
 translation

---
 .../Sql.Drivers.MySql/v8_0/Compiler.cs        | 24 +++++++++++++++++++
 .../Sql.Drivers.MySql/v8_0/Translator.cs      | 15 ------------
 2 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
index 5fc7f46b43..e98d666a59 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
@@ -4,10 +4,34 @@
 // Created by: Alexey Kulakov
 // Created:    2022.02.03
 
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Dml;
+
 namespace Xtensive.Sql.Drivers.MySql.v8_0
 {
   internal class Compiler : v5_7.Compiler
   {
+    /// <inheritdoc/>
+    public override void Visit(SqlQueryExpression node)
+    {
+      using (context.EnterScope(node)) {
+        bool needOpeningParenthesis = true;
+        bool needClosingParenthesis = true;
+
+        AppendTranslatedEntry(node);
+        _ = context.Output.Append("(");
+        node.Left.AcceptVisitor(this);
+        _ = context.Output.Append(")");
+        AppendTranslated(node.NodeType);
+        AppendTranslated(node, QueryExpressionSection.All);
+        _ = context.Output.Append("(");
+        node.Right.AcceptVisitor(this);
+        _ = context.Output.Append(")");
+        AppendTranslatedExit(node);
+      }
+    }
+
+
     // Constructors
 
     public Compiler(SqlDriver driver)
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
index ecea47bab2..11d884df68 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
@@ -12,21 +12,6 @@ namespace Xtensive.Sql.Drivers.MySql.v8_0
 {
   internal class Translator : v5_7.Translator
   {
-    /// <inheritdoc/>
-    public override string Translate(SqlCompilerContext context, SqlCast node, NodeSection section)
-    {
-      if (node.Type.Type==SqlType.DateTime)
-        switch (section) {
-        case NodeSection.Entry:
-          return "CAST(";
-        case NodeSection.Exit:
-          return "AS " + Translate(node.Type) + "(6))";
-        default:
-          throw new ArgumentOutOfRangeException("section");
-        }
-      return base.Translate(context, node, section);
-    }
-
     // Constructors
 
     public Translator(SqlDriver driver)

From 2f102502c2f5ea4a01d93edc9921e4339e66a1a1 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Tue, 7 Jun 2022 18:07:01 +0500
Subject: [PATCH 05/14] Fix wrong choice of driver

---
 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
index db4c3343fa..c810ad1c4b 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
@@ -122,7 +122,7 @@ private static SqlDriver CreateDriverInstance(string connectionString, Version v
         5 when version.Minor == 1 => new v5_1.Driver(coreServerInfo),
         5 when version.Minor == 5 => new v5_5.Driver(coreServerInfo),
         5 when version.Minor == 6 => new v5_6.Driver(coreServerInfo),
-        5 when version.Major == 7 => new v5_7.Driver(coreServerInfo),
+        5 when version.Minor == 7 => new v5_7.Driver(coreServerInfo),
         6 => throw new NotSupportedException(),
         7 => throw new NotSupportedException(),
         8 => new v8_0.Driver(coreServerInfo),

From 86665849d68420ead8b88dff949ea5bc87c9d69d Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 8 Jun 2022 20:27:31 +0500
Subject: [PATCH 06/14] Tests for UNION wrapping in new MySql v8

---
 .../MySQL/ChinookTest.cs                      | 257 ++++++++++++++++++
 1 file changed, 257 insertions(+)

diff --git a/Orm/Xtensive.Orm.Tests.Sql/MySQL/ChinookTest.cs b/Orm/Xtensive.Orm.Tests.Sql/MySQL/ChinookTest.cs
index 1695460888..41ee3c306b 100644
--- a/Orm/Xtensive.Orm.Tests.Sql/MySQL/ChinookTest.cs
+++ b/Orm/Xtensive.Orm.Tests.Sql/MySQL/ChinookTest.cs
@@ -957,5 +957,262 @@ public void Test052()
 
       Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
     }
+
+    [Test]
+    public void Test053()
+    {
+      Require.ProviderVersionAtLeast(new Version(8, 0));
+
+      var nativeSql =
+        "SELECT `a`.`ArtistId` FROM ((SELECT ArtistId FROM dotest.album where AlbumId >= 0 and AlbumId < 50 LIMIT 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 50 and AlbumId < 100 LIMIT 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 100 and AlbumId < 200 LIMIT 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 20 and AlbumId < 300 LIMIT 10)) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["ArtistId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+      s1.Limit = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["ArtistId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+      s2.Limit = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["ArtistId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+      s3.Limit = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["ArtistId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+      s4.Limit = 10;
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["ArtistId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
+
+    [Test]
+    public void Test054()
+    {
+      Require.ProviderVersionAtLeast(new Version(8, 0));
+
+      var nativeSql =
+        "SELECT `a`.`ArtistId` FROM ((SELECT ArtistId FROM dotest.album where AlbumId >= 0 and AlbumId < 50 LIMIT 10 OFFSET 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 50 and AlbumId < 100 LIMIT 10 OFFSET 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 100 and AlbumId < 200 LIMIT 10 OFFSET 10)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 20 and AlbumId < 300 LIMIT 10 OFFSET 10)) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["ArtistId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+      s1.Limit = 10;
+      s1.Offset = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["ArtistId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+      s2.Limit = 10;
+      s2.Offset = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["ArtistId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+      s3.Limit = 10;
+      s3.Offset = 10;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["ArtistId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+      s4.Limit = 10;
+      s4.Offset = 10;
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["ArtistId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
+
+    [Test]
+    public void Test055()
+    {
+      Require.ProviderVersionAtLeast(new Version(8, 0));
+
+      var nativeSql =
+        "SELECT `a`.`ArtistId` FROM ((SELECT ArtistId FROM dotest.album where AlbumId >= 0 and AlbumId < 50 FOR SHARE)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 50 and AlbumId < 100 FOR SHARE)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 100 and AlbumId < 200 FOR SHARE)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 20 and AlbumId < 300 FOR SHARE)) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["ArtistId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+      s1.Lock = SqlLockType.Shared;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["ArtistId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+      s2.Lock = SqlLockType.Shared;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["ArtistId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+      s3.Lock = SqlLockType.Shared;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["ArtistId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+      s4.Lock = SqlLockType.Shared;
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["ArtistId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
+
+    [Test]
+    public void Test056()
+    {
+      Require.ProviderVersionAtLeast(new Version(8, 0));
+
+      var nativeSql =
+        "SELECT `a`.`ArtistId` FROM ((SELECT ArtistId FROM dotest.album where AlbumId >= 0 and AlbumId < 50 ORDER BY ArtistId)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 50 and AlbumId < 100 ORDER BY ArtistId)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 100 and AlbumId < 200 ORDER BY ArtistId)"
+        + " UNION (SELECT ArtistId FROM dotest.album where AlbumId >= 20 and AlbumId < 300 ORDER BY ArtistId)) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["ArtistId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+      s1.OrderBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["ArtistId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+      s2.OrderBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["ArtistId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+      s3.OrderBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["ArtistId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+      s4.OrderBy.Add(albums.Columns["ArtistId"]);
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["ArtistId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
+
+
+    [Test]
+    public void Test057()
+    {
+      Require.ProviderVersionAtLeast(new Version(8, 0));
+
+      var nativeSql =
+        "SELECT `a`.`ArtistId` FROM (SELECT ArtistId FROM dotest.album where AlbumId >= 0 and AlbumId < 50 GROUP BY ArtistId"
+        + " UNION SELECT ArtistId FROM dotest.album where AlbumId >= 50 and AlbumId < 100 GROUP BY ArtistId"
+        + " UNION SELECT ArtistId FROM dotest.album where AlbumId >= 100 and AlbumId < 200 GROUP BY ArtistId"
+        + " UNION SELECT ArtistId FROM dotest.album where AlbumId >= 20 and AlbumId < 300 GROUP BY ArtistId) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["ArtistId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+      s1.GroupBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["ArtistId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+      s2.GroupBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["ArtistId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+      s3.GroupBy.Add(albums.Columns["ArtistId"]);
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["ArtistId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+      s4.GroupBy.Add(albums.Columns["ArtistId"]);
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["ArtistId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
+
+    [Test]
+    public void Test058()
+    {
+      var nativeSql =
+        "SELECT `a`.`AlbumId` FROM (SELECT AlbumId FROM dotest.album where AlbumId >= 0 and AlbumId < 50"
+        + " UNION SELECT AlbumId FROM dotest.album where AlbumId >= 50 and AlbumId< 100"
+        + " UNION SELECT AlbumId FROM dotest.album where AlbumId >= 100 and AlbumId< 200"
+        + " UNION SELECT AlbumId FROM dotest.album where AlbumId >= 20 and AlbumId< 300) `a`;";
+
+      var albums = SqlDml.TableRef(schema.Tables["album"]);
+
+      var s1 = SqlDml.Select(albums);
+      s1.Columns.Add(albums.Columns["AlbumId"]);
+      s1.Where = albums.Columns["AlbumId"] >= 0 && albums.Columns["AlbumId"] < 50;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s2 = SqlDml.Select(albums);
+      s2.Columns.Add(albums.Columns["AlbumId"]);
+      s2.Where = albums.Columns["AlbumId"] >= 50 && albums.Columns["AlbumId"] < 100;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s3 = SqlDml.Select(albums);
+      s3.Columns.Add(albums.Columns["AlbumId"]);
+      s3.Where = albums.Columns["AlbumId"] >= 100 && albums.Columns["AlbumId"] < 200;
+
+      albums = SqlDml.TableRef(schema.Tables["album"]);
+      var s4 = SqlDml.Select(albums);
+      s4.Columns.Add(albums.Columns["AlbumId"]);
+      s4.Where = albums.Columns["AlbumId"] >= 200 && albums.Columns["AlbumId"] < 300;
+
+      var qr = SqlDml.QueryRef(s1.Union(s2).Union(s3.Union(s4)), "a");
+      var select = SqlDml.Select(qr);
+      select.Columns.Add(qr["AlbumId"]);
+
+      Assert.IsTrue(CompareExecuteNonQuery(nativeSql, select));
+    }
   }
 }

From ba977c36d0f550e6dfd63b68dca976a44130e891 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 8 Jun 2022 20:43:07 +0500
Subject: [PATCH 07/14] New wrapping algorithm for SubQueries

---
 .../Sql.Drivers.MySql/v8_0/Compiler.cs        | 30 ++++++++++++++-----
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
index e98d666a59..d8be540c24 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
@@ -15,18 +15,32 @@ internal class Compiler : v5_7.Compiler
     public override void Visit(SqlQueryExpression node)
     {
       using (context.EnterScope(node)) {
-        bool needOpeningParenthesis = true;
-        bool needClosingParenthesis = true;
+        var wrapLeft = node.Left is SqlSelect sL
+          && (sL.OrderBy.Count > 0 || !sL.HasLimit || sL.Lock != SqlLockType.Empty);
+        var wrapRight = node.Left is SqlSelect sR
+          && (sR.OrderBy.Count > 0 || !sR.HasLimit || sR.Lock != SqlLockType.Empty);
 
         AppendTranslatedEntry(node);
-        _ = context.Output.Append("(");
-        node.Left.AcceptVisitor(this);
-        _ = context.Output.Append(")");
+        if (wrapLeft) {
+          _ = context.Output.Append("(");
+          node.Left.AcceptVisitor(this);
+          _ = context.Output.Append(")");
+        }
+        else {
+          node.Left.AcceptVisitor(this);
+        }
+
         AppendTranslated(node.NodeType);
         AppendTranslated(node, QueryExpressionSection.All);
-        _ = context.Output.Append("(");
-        node.Right.AcceptVisitor(this);
-        _ = context.Output.Append(")");
+
+        if (wrapRight) {
+          _ = context.Output.Append("(");
+          node.Right.AcceptVisitor(this);
+          _ = context.Output.Append(")");
+        }
+        else {
+          node.Right.AcceptVisitor(this);
+        }
         AppendTranslatedExit(node);
       }
     }

From c4b83e97188a869948686768ac930554176447a2 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 8 Jun 2022 20:45:12 +0500
Subject: [PATCH 08/14] SqlLockType proper translation for MySql v8.0

---
 .../Sql.Drivers.MySql/v8_0/Translator.cs      | 19 +++++++++++++++++++
 Orm/Xtensive.Orm/Sql/Dml/Extensions.cs        |  5 +++++
 2 files changed, 24 insertions(+)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
index 11d884df68..e69cd1edbc 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Translator.cs
@@ -12,6 +12,25 @@ namespace Xtensive.Sql.Drivers.MySql.v8_0
 {
   internal class Translator : v5_7.Translator
   {
+    /// <inheritdoc/>
+    public override void Translate(IOutput output, SqlLockType lockType)
+    {
+      var forShare = lockType.Supports(SqlLockType.Shared);
+      var forUpdate = lockType.SupportsAny(SqlLockType.Update | SqlLockType.Exclusive);
+
+      if (!forShare && !forUpdate) {
+        throw new NotSupportedException($"Lock '{lockType.ToString(true)}' is not supported.");
+      }
+
+      _ = output
+        .Append(forShare ? "FOR SHARE" : "FOR UPDATE")
+        .Append(lockType.Supports(SqlLockType.SkipLocked)
+          ? " SKIP LOCKED"
+          : lockType.Supports(SqlLockType.ThrowIfLocked)
+            ? " NOWAIT"
+            : string.Empty);
+    }
+
     // Constructors
 
     public Translator(SqlDriver driver)
diff --git a/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs b/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
index f08ceb74d5..a1eb6b44f4 100644
--- a/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
+++ b/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
@@ -33,6 +33,11 @@ public static bool Supports(this SqlLockType available, SqlLockType required)
       return (available & required)==required;
     }
 
+    public static bool SupportsAny(this SqlLockType available, SqlLockType required)
+    {
+      return (available | required) == required;
+    }
+
     public static string ToString(this SqlLockType lockType, bool humanReadable)
     {
       if (!humanReadable)

From 07c040a719d95c672b44d9760ea9a23ed3838c74 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Thu, 9 Jun 2022 10:40:27 +0500
Subject: [PATCH 09/14] Fix incorrect condition

---
 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
index d8be540c24..0e2fa17ca5 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
@@ -16,9 +16,9 @@ public override void Visit(SqlQueryExpression node)
     {
       using (context.EnterScope(node)) {
         var wrapLeft = node.Left is SqlSelect sL
-          && (sL.OrderBy.Count > 0 || !sL.HasLimit || sL.Lock != SqlLockType.Empty);
+          && (sL.OrderBy.Count > 0 || sL.HasLimit || sL.Lock != SqlLockType.Empty);
         var wrapRight = node.Left is SqlSelect sR
-          && (sR.OrderBy.Count > 0 || !sR.HasLimit || sR.Lock != SqlLockType.Empty);
+          && (sR.OrderBy.Count > 0 || sR.HasLimit || sR.Lock != SqlLockType.Empty);
 
         AppendTranslatedEntry(node);
         if (wrapLeft) {

From 95436f9021c136e4582dbbf073c8f49776b58ca0 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Thu, 9 Jun 2022 19:16:34 +0500
Subject: [PATCH 10/14] Round brackets for SqlQueryExpression for MySql v5.7

---
 .../Sql.Drivers.MySql/v5_7/Compiler.cs        | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
index b12423abd2..383b42888b 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_7/Compiler.cs
@@ -4,10 +4,47 @@
 // Created by: Alexey Kulakov
 // Created:    2022.02.03
 
+using Xtensive.Sql.Compiler;
+using Xtensive.Sql.Dml;
+
 namespace Xtensive.Sql.Drivers.MySql.v5_7
 {
   internal class Compiler : v5_6.Compiler
   {
+    /// <inheritdoc/>
+    public override void Visit(SqlQueryExpression node)
+    {
+      using (context.EnterScope(node)) {
+        var wrapLeft = node.Left is SqlSelect sL
+          && (sL.OrderBy.Count > 0 || sL.HasLimit || sL.Lock != SqlLockType.Empty);
+        var wrapRight = node.Left is SqlSelect sR
+          && (sR.OrderBy.Count > 0 || sR.HasLimit || sR.Lock != SqlLockType.Empty);
+
+        AppendTranslatedEntry(node);
+        if (wrapLeft) {
+          _ = context.Output.Append("(");
+          node.Left.AcceptVisitor(this);
+          _ = context.Output.Append(")");
+        }
+        else {
+          node.Left.AcceptVisitor(this);
+        }
+
+        AppendTranslated(node.NodeType);
+        AppendTranslated(node, QueryExpressionSection.All);
+
+        if (wrapRight) {
+          _ = context.Output.Append("(");
+          node.Right.AcceptVisitor(this);
+          _ = context.Output.Append(")");
+        }
+        else {
+          node.Right.AcceptVisitor(this);
+        }
+        AppendTranslatedExit(node);
+      }
+    }
+
     // Constructors
 
     public Compiler(SqlDriver driver)

From de91fe0aced8052413e63fe23c1f025f6a909c93 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Fri, 10 Jun 2022 10:54:31 +0500
Subject: [PATCH 11/14] Remove the v8.0's overriding method, the v5.7's is
 enough

---
 .../Sql.Drivers.MySql/v8_0/Compiler.cs        | 37 -------------------
 1 file changed, 37 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
index 0e2fa17ca5..d67a0840b1 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v8_0/Compiler.cs
@@ -4,47 +4,10 @@
 // Created by: Alexey Kulakov
 // Created:    2022.02.03
 
-using Xtensive.Sql.Compiler;
-using Xtensive.Sql.Dml;
-
 namespace Xtensive.Sql.Drivers.MySql.v8_0
 {
   internal class Compiler : v5_7.Compiler
   {
-    /// <inheritdoc/>
-    public override void Visit(SqlQueryExpression node)
-    {
-      using (context.EnterScope(node)) {
-        var wrapLeft = node.Left is SqlSelect sL
-          && (sL.OrderBy.Count > 0 || sL.HasLimit || sL.Lock != SqlLockType.Empty);
-        var wrapRight = node.Left is SqlSelect sR
-          && (sR.OrderBy.Count > 0 || sR.HasLimit || sR.Lock != SqlLockType.Empty);
-
-        AppendTranslatedEntry(node);
-        if (wrapLeft) {
-          _ = context.Output.Append("(");
-          node.Left.AcceptVisitor(this);
-          _ = context.Output.Append(")");
-        }
-        else {
-          node.Left.AcceptVisitor(this);
-        }
-
-        AppendTranslated(node.NodeType);
-        AppendTranslated(node, QueryExpressionSection.All);
-
-        if (wrapRight) {
-          _ = context.Output.Append("(");
-          node.Right.AcceptVisitor(this);
-          _ = context.Output.Append(")");
-        }
-        else {
-          node.Right.AcceptVisitor(this);
-        }
-        AppendTranslatedExit(node);
-      }
-    }
-
 
     // Constructors
 

From 3aa9d48b63ffe83212dd94d973c2dfecbedc886f Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 15 Jun 2022 14:50:27 +0500
Subject: [PATCH 12/14] Remove accidentally added new line at the end of file

---
 Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
index 9020a1acba..3aa8feb24a 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs
@@ -275,4 +275,4 @@ protected internal Compiler(SqlDriver driver)
     {
     }
   }
-}
+}
\ No newline at end of file

From 130c53c4af5b8df4f3d4bc4007c12fd0c775e0a6 Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 15 Jun 2022 15:16:04 +0500
Subject: [PATCH 13/14] Summaries for files and methods

---
 .../Sql.Drivers.MySql/DriverFactory.cs        |  2 +-
 Orm/Xtensive.Orm/Sql/Dml/Extensions.cs        | 24 ++++++++++++++++---
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
index c810ad1c4b..8c6993157c 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2021 Xtensive LLC.
+// Copyright (C) 2011-2022 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Malisa Ncube
diff --git a/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs b/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
index a1eb6b44f4..be14016706 100644
--- a/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
+++ b/Orm/Xtensive.Orm/Sql/Dml/Extensions.cs
@@ -1,6 +1,6 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2009-2022 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
 // Created:    2009.08.24
 
@@ -28,11 +28,29 @@ public static bool IsNullReference(this SqlExpression expression)
       return ReferenceEquals(expression, null);
     }
 
+    /// <summary>
+    /// Checks whether <paramref name="available"/> contains all flags of given <paramref name="required"/>.
+    /// </summary>
+    /// <param name="available">All flags.</param>
+    /// <param name="required">Flags to check existance.</param>
+    /// <returns>
+    /// <see langword="true"/> if <paramref name="available"/> contains all flags of <paramref name="required"/>,
+    /// otherwise, <see langword="false"/>.
+    /// </returns>
     public static bool Supports(this SqlLockType available, SqlLockType required)
     {
       return (available & required)==required;
     }
 
+    /// <summary>
+    /// Checks whether <paramref name="available"/> contains any flag of given <paramref name="required"/>.
+    /// </summary>
+    /// <param name="available">All flags.</param>
+    /// <param name="required">Flags to check existance.</param>
+    /// <returns>
+    /// <see langword="true"/> if <paramref name="available"/> contains any flag of <paramref name="required"/>,
+    /// otherwise, <see langword="false"/>.
+    /// </returns>
     public static bool SupportsAny(this SqlLockType available, SqlLockType required)
     {
       return (available | required) == required;

From 65947a7f21b13493067c768cd598479926cb1bfc Mon Sep 17 00:00:00 2001
From: Alexey Kulakov <alexey.kulakov@dataobjects.net>
Date: Wed, 15 Jun 2022 16:08:25 +0500
Subject: [PATCH 14/14] Message for exception

---
 .../Sql.Drivers.MySql/DriverFactory.cs         |  3 +--
 .../Resources/Strings.Designer.cs              | 11 ++++++++++-
 .../Sql.Drivers.MySql/Resources/Strings.resx   |  3 +++
 .../Xtensive.Orm.MySql.csproj                  | 18 ++++++++++++------
 4 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
index 8c6993157c..8be25beb36 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/DriverFactory.cs
@@ -123,8 +123,7 @@ private static SqlDriver CreateDriverInstance(string connectionString, Version v
         5 when version.Minor == 5 => new v5_5.Driver(coreServerInfo),
         5 when version.Minor == 6 => new v5_6.Driver(coreServerInfo),
         5 when version.Minor == 7 => new v5_7.Driver(coreServerInfo),
-        6 => throw new NotSupportedException(),
-        7 => throw new NotSupportedException(),
+        6 or 7 => throw new NotSupportedException(string.Format(Strings.ExVersionXOfMySQLIsNotSupported, version)),
         8 => new v8_0.Driver(coreServerInfo),
         _ => new v8_0.Driver(coreServerInfo)
       };
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.Designer.cs b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.Designer.cs
index ee0df2c30d..82f4da2092 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.Designer.cs
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.Designer.cs
@@ -19,7 +19,7 @@ namespace Xtensive.Sql.Drivers.MySql.Resources {
     // class via a tool like ResGen or Visual Studio.
     // To add or remove a member, edit your .ResX file then rerun ResGen
     // with the /str option, or rebuild your VS project.
-    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "15.0.0.0")]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
     internal class Strings {
@@ -113,5 +113,14 @@ internal static string ExUserNameRequired {
                 return ResourceManager.GetString("ExUserNameRequired", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Version {0} of MySQL is not supported..
+        /// </summary>
+        internal static string ExVersionXOfMySQLIsNotSupported {
+            get {
+                return ResourceManager.GetString("ExVersionXOfMySQLIsNotSupported", resourceCulture);
+            }
+        }
     }
 }
diff --git a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.resx b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.resx
index b8e8b5ec35..aec58aa70e 100644
--- a/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.resx
+++ b/Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/Resources/Strings.resx
@@ -135,4 +135,7 @@
   <data name="ExUserNameRequired" xml:space="preserve">
     <value>MySQL Username is required.</value>
   </data>
+  <data name="ExVersionXOfMySQLIsNotSupported" xml:space="preserve">
+    <value>Version {0} of MySQL is not supported.</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/Orm/Xtensive.Orm.MySql/Xtensive.Orm.MySql.csproj b/Orm/Xtensive.Orm.MySql/Xtensive.Orm.MySql.csproj
index d2b6fc6ca7..68c6b51e0c 100644
--- a/Orm/Xtensive.Orm.MySql/Xtensive.Orm.MySql.csproj
+++ b/Orm/Xtensive.Orm.MySql/Xtensive.Orm.MySql.csproj
@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <IsPackable>true</IsPackable>
     <DocumentationFile>$(OutputPath)$(TargetFramework)\$(AssemblyName).xml</DocumentationFile>
@@ -23,15 +23,21 @@
     </Compile>
   </ItemGroup>
   <ItemGroup>
-    <Compile Update="Sql.Drivers.MySql\Resources\Strings.Designer.cs">
-      <DesignTime>True</DesignTime>
-      <AutoGen>True</AutoGen>
-      <DependentUpon>Strings.resx</DependentUpon>
-    </Compile>
+    <EmbeddedResource Update="Sql.Drivers.MySql\Resources\Strings.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>Strings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Google.Protobuf" Version="3.15.0" />
     <PackageReference Include="MySql.Data" Version="8.0.19" />
     <PackageReference Include="System.Xml.XPath.XmlDocument" Version="4.3.0" />
   </ItemGroup>
+  <ItemGroup>
+    <Compile Update="Sql.Drivers.MySql\Resources\Strings.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Strings.resx</DependentUpon>
+    </Compile>
+  </ItemGroup>
 </Project>