Migrations: Generate transaction statements in SQL script

Fixes dotnet#7681

src/EFCore.Design/Design/OperationExecutor.cs

@@ -269,6 +269,7 @@ public class ScriptMigration : OperationBase
             ///     <para><c>fromMigration</c>--The starting migration. Defaults to <see cref="Migration.InitialDatabase" />.</para>
             ///     <para><c>toMigration</c>--The ending migration. Defaults to the last migration.</para>
             ///     <para><c>idempotent</c>--Generate a script that can be used on a database at any migration.</para>
+            ///     <para><c>noTransactions</c>--Don't generate SQL transaction statements.</para>
             ///     <para><c>contextType</c>--The <see cref="DbContext" /> to use.</para>
             /// </summary>
             /// <param name="executor"> The operation executor. </param>
@@ -286,23 +287,29 @@ public ScriptMigration(
                 var fromMigration = (string)args["fromMigration"];
                 var toMigration = (string)args["toMigration"];
                 var idempotent = (bool)args["idempotent"];
+                var noTransactions = (bool)(args["noTransactions"] ?? false);
                 var contextType = (string)args["contextType"];
 
-                Execute(() => executor.ScriptMigrationImpl(fromMigration, toMigration, idempotent, contextType));
+                Execute(() => executor.ScriptMigrationImpl(fromMigration, toMigration, idempotent, noTransactions, contextType));
             }
         }
 
         private string ScriptMigrationImpl(
             [CanBeNull] string fromMigration,
             [CanBeNull] string toMigration,
             bool idempotent,
+            bool noTransactions,
             [CanBeNull] string contextType)
         {
             var options = MigrationsSqlGenerationOptions.Default;
             if (idempotent)
             {
                 options |= MigrationsSqlGenerationOptions.Idempotent;
             }
+            if (noTransactions)
+            {
+                options |= MigrationsSqlGenerationOptions.NoTransactions;
+            }
 
             return MigrationsOperations.ScriptMigration(
                 fromMigration,

src/EFCore.Relational/Migrations/Internal/Migrator.cs

@@ -308,6 +308,7 @@ public virtual string GenerateScript(
             options |= MigrationsSqlGenerationOptions.Script;
 
             var idempotent = options.HasFlag(MigrationsSqlGenerationOptions.Idempotent);
+            var noTransactions = options.HasFlag(MigrationsSqlGenerationOptions.NoTransactions);
 
             IEnumerable<string> appliedMigrations;
             if (string.IsNullOrEmpty(fromMigration)
@@ -335,10 +336,13 @@ public virtual string GenerateScript(
             if (fromMigration == Migration.InitialDatabase
                 || string.IsNullOrEmpty(fromMigration))
             {
-                builder.AppendLine(_historyRepository.GetCreateIfNotExistsScript());
-                builder.Append(_sqlGenerationHelper.BatchTerminator);
+                builder
+                    .Append(_historyRepository.GetCreateIfNotExistsScript())
+                    .Append(_sqlGenerationHelper.BatchTerminator);
             }
 
+            var transactionStarted = false;
+
             for (var i = 0; i < migrationsToRevert.Count; i++)
             {
                 var migration = migrationsToRevert[i];
@@ -350,6 +354,24 @@ public virtual string GenerateScript(
 
                 foreach (var command in GenerateDownSql(migration, previousMigration, options))
                 {
+                    if (!noTransactions)
+                    {
+                        if (!transactionStarted && !command.TransactionSuppressed)
+                        {
+                            builder
+                                .AppendLine(_sqlGenerationHelper.StartTransaction)
+                                .Append(_sqlGenerationHelper.BatchTerminator);
+                            transactionStarted = true;
+                        }
+                        if (transactionStarted && command.TransactionSuppressed)
+                        {
+                            builder
+                                .AppendLine(_sqlGenerationHelper.Commit)
+                                .Append(_sqlGenerationHelper.BatchTerminator);
+                            transactionStarted = false;
+                        }
+                    }
+
                     if (idempotent)
                     {
                         builder.AppendLine(_historyRepository.GetBeginIfExistsScript(migration.GetId()));
@@ -358,15 +380,23 @@ public virtual string GenerateScript(
                             builder.AppendLines(command.CommandText);
                         }
 
-                        builder.AppendLine(_historyRepository.GetEndIfScript());
+                        builder.Append(_historyRepository.GetEndIfScript());
                     }
                     else
                     {
-                        builder.AppendLine(command.CommandText);
+                        builder.Append(command.CommandText);
                     }
 
                     builder.Append(_sqlGenerationHelper.BatchTerminator);
                 }
+
+                if (!noTransactions && transactionStarted)
+                {
+                    builder
+                        .AppendLine(_sqlGenerationHelper.Commit)
+                        .Append(_sqlGenerationHelper.BatchTerminator);
+                    transactionStarted = false;
+                }
             }
 
             foreach (var migration in migrationsToApply)
@@ -375,6 +405,24 @@ public virtual string GenerateScript(
 
                 foreach (var command in GenerateUpSql(migration, options))
                 {
+                    if (!noTransactions)
+                    {
+                        if (!transactionStarted && !command.TransactionSuppressed)
+                        {
+                            builder
+                                .AppendLine(_sqlGenerationHelper.StartTransaction)
+                                .Append(_sqlGenerationHelper.BatchTerminator);
+                            transactionStarted = true;
+                        }
+                        if (transactionStarted && command.TransactionSuppressed)
+                        {
+                            builder
+                                .AppendLine(_sqlGenerationHelper.Commit)
+                                .Append(_sqlGenerationHelper.BatchTerminator);
+                            transactionStarted = false;
+                        }
+                    }
+
                     if (idempotent)
                     {
                         builder.AppendLine(_historyRepository.GetBeginIfNotExistsScript(migration.GetId()));
@@ -383,15 +431,23 @@ public virtual string GenerateScript(
                             builder.AppendLines(command.CommandText);
                         }
 
-                        builder.AppendLine(_historyRepository.GetEndIfScript());
+                        builder.Append(_historyRepository.GetEndIfScript());
                     }
                     else
                     {
-                        builder.AppendLine(command.CommandText);
+                        builder.Append(command.CommandText);
                     }
 
                     builder.Append(_sqlGenerationHelper.BatchTerminator);
                 }
+
+                if (!noTransactions && transactionStarted)
+                {
+                    builder
+                        .AppendLine(_sqlGenerationHelper.Commit)
+                        .Append(_sqlGenerationHelper.BatchTerminator);
+                    transactionStarted = false;
+                }
             }
 
             return builder.ToString();

src/EFCore.Relational/Migrations/MigrationsSqlGenerationOptions.cs

@@ -24,6 +24,11 @@ public enum MigrationsSqlGenerationOptions
         /// <summary>
         ///     Generate SQL for an idempotent script.
         /// </summary>
-        Idempotent = 1 << 1
+        Idempotent = 1 << 1,
+
+        /// <summary>
+        ///     Generate SQL for a script without transaction statements.
+        /// </summary>
+        NoTransactions = 1 << 2
     }
 }

src/EFCore.Relational/Storage/ISqlGenerationHelper.cs

@@ -33,6 +33,16 @@ public interface ISqlGenerationHelper
         /// </summary>
         string BatchTerminator { get; }
 
+        /// <summary>
+        ///     Gets the SQL for a START TRANSACTION statement.
+        /// </summary>
+        string StartTransaction { get; }
+
+        /// <summary>
+        ///     Gets the SQL for a COMMIT statement.
+        /// </summary>
+        string Commit { get; }
+
         /// <summary>
         ///     The default single-line comment prefix.
         /// </summary>

src/EFCore.Relational/Storage/RelationalSqlGenerationHelper.cs

@@ -43,7 +43,13 @@ public RelationalSqlGenerationHelper([NotNull] RelationalSqlGenerationHelperDepe
         /// <summary>
         ///     The terminator to be used for batches of SQL statements.
         /// </summary>
-        public virtual string BatchTerminator => string.Empty;
+        public virtual string BatchTerminator => Environment.NewLine;
+
+        /// <inheritdoc />
+        public virtual string StartTransaction => "START TRANSACTION" + StatementTerminator;
+
+        /// <inheritdoc />
+        public virtual string Commit => "COMMIT" + StatementTerminator;
 
         /// <summary>
         ///     The default single-line comment prefix.

src/EFCore.SqlServer/Storage/Internal/SqlServerSqlGenerationHelper.cs

@@ -44,6 +44,14 @@ public SqlServerSqlGenerationHelper([NotNull] RelationalSqlGenerationHelperDepen
         /// </summary>
         public override string BatchTerminator => "GO" + Environment.NewLine + Environment.NewLine;
 
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public override string StartTransaction => "BEGIN TRANSACTION" + StatementTerminator;
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

src/EFCore.Sqlite.Core/Storage/Internal/SqliteSqlGenerationHelper.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Text;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Storage;
@@ -34,6 +35,15 @@ public SqliteSqlGenerationHelper([NotNull] RelationalSqlGenerationHelperDependen
         {
         }
 
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public override string StartTransaction
+            => "BEGIN TRANSACTION" + StatementTerminator;
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in