Transaction and Bulk Copy Operations
Bulk copy operations can be performed as isolated operations or as part of a multiple step transaction. This latter option enables you to perform more than one bulk copy operation within the same transaction, as well as perform other database operations (such as inserts, updates, and deletes) while still being able to commit or roll back the entire transaction.
By default, a bulk copy operation is performed as an isolated operation. The bulk copy operation occurs in a non-transacted way, with no opportunity for rolling it back. If you need to roll back all or part of the bulk copy when an error occurs, you can use a SqlBulkCopy-managed transaction, perform the bulk copy operation within an existing transaction, or be enlisted in a System.TransactionsTransaction.
Performing a Non-transacted Bulk Copy Operation
The following Console application shows what happens when a non-transacted bulk copy operation encounters an error partway through the operation.
In the example, the source table and destination table each include an Identity column named ProductID. The code first prepares the destination table by deleting all rows and then inserting a single row whose ProductID is known to exist in the source table. By default, a new value for the Identity column is generated in the destination table for each row added. In this example, an option is set when the connection is opened that forces the bulk load process to use the Identity values from the source table instead.
The bulk copy operation is executed with the BatchSize property set to 10. When the operation encounters the invalid row, an exception is thrown. In this first example, the bulk copy operation is non-transacted. All batches copied up to the point of the error are committed; the batch containing the duplicate key is rolled back, and the bulk copy operation is halted before processing any other batches.
Note
This sample will not run unless you have created the work tables as described in Bulk Copy Example Setup. This code is provided to demonstrate the syntax for using SqlBulkCopy only. If the source and destination tables are located in the same SQL Server instance, it is easier and faster to use a Transact-SQLINSERT … SELECT statement to copy the data.
var connectionString = GetConnectionString();
// Open a sourceConnection to the AdventureWorks database.
using (SqlConnection sourceConnection =
new(connectionString))
{
sourceConnection.Open();
// Delete all from the destination table.
SqlCommand commandDelete = new()
{
Connection = sourceConnection,
CommandText =
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
};
commandDelete.ExecuteNonQuery();
// Add a single row that will result in duplicate key
// when all rows from source are bulk copied.
// Note that this technique will only be successful in
// illustrating the point if a row with ProductID = 446
// exists in the AdventureWorks Production.Products table.
// If you have made changes to the data in this table, change
// the SQL statement in the code to add a ProductID that
// does exist in your version of the Production.Products
// table. Choose any ProductID in the middle of the table
// (not first or last row) to best illustrate the result.
SqlCommand commandInsert = new()
{
Connection = sourceConnection,
CommandText =
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" +
"INSERT INTO " + "dbo.BulkCopyDemoMatchingColumns " +
"([ProductID], [Name] ,[ProductNumber]) " +
"VALUES(446, 'Lock Nut 23','LN-3416');" +
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
};
commandInsert.ExecuteNonQuery();
// Perform an initial count on the destination table.
SqlCommand commandRowCount = new(
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;",
sourceConnection);
long countStart = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Starting row count = {0}", countStart);
// Get data from the source table as a SqlDataReader.
SqlCommand commandSourceData = new(
"SELECT ProductID, Name, ProductNumber " +
"FROM Production.Product;", sourceConnection);
SqlDataReader reader = commandSourceData.ExecuteReader();
// Set up the bulk copy object using the KeepIdentity option.
using (SqlBulkCopy bulkCopy = new(
connectionString, SqlBulkCopyOptions.KeepIdentity))
{
bulkCopy.BatchSize = 10;
bulkCopy.DestinationTableName =
"dbo.BulkCopyDemoMatchingColumns";
// Write from the source to the destination.
// This should fail with a duplicate key error
// after some of the batches have been copied.
try
{
bulkCopy.WriteToServer(reader);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
reader.Close();
}
}
// Perform a final count on the destination
// table to see how many rows were added.
long countEnd = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Ending row count = {0}", countEnd);
Console.WriteLine("{0} rows were added.", countEnd - countStart);
Console.WriteLine("Press Enter to finish.");
Console.ReadLine();
}
Imports System.Data.SqlClient
Module Module1
Sub Main()
Dim connectionString As String = GetConnectionString()
' Open a sourceConnection to the AdventureWorks database.
Using sourceConnection As SqlConnection = _
New SqlConnection(connectionString)
sourceConnection.Open()
' Delete all from the destination table.
Dim commandDelete As New SqlCommand
commandDelete.Connection = sourceConnection
commandDelete.CommandText = _
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
commandDelete.ExecuteNonQuery()
' Add a single row that will result in duplicate key
' when all rows from source are bulk copied.
' Note that this technique will only be successful in
' illustrating the point if a row with ProductID = 446
' exists in the AdventureWorks Production.Products table.
' If you have made changes to the data in this table, change
' the SQL statement in the code to add a ProductID that
' does exist in your version of the Production.Products
' table. Choose any ProductID in the middle of the table
' (not first or last row) to best illustrate the result.
Dim commandInsert As New SqlCommand
commandInsert.Connection = sourceConnection
commandInsert.CommandText = _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" & _
"INSERT INTO dbo.BulkCopyDemoMatchingColumns " & _
"([ProductID], [Name] ,[ProductNumber]) " & _
"VALUES(446, 'Lock Nut 23','LN-3416');" & _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
commandInsert.ExecuteNonQuery()
' Perform an initial count on the destination table.
Dim commandRowCount As New SqlCommand( _
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;", _
sourceConnection)
Dim countStart As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Starting row count = {0}", countStart)
' Get data from the source table as a SqlDataReader.
Dim commandSourceData As SqlCommand = New SqlCommand( _
"SELECT ProductID, Name, ProductNumber " & _
"FROM Production.Product;", sourceConnection)
Dim reader As SqlDataReader = _
commandSourceData.ExecuteReader()
' Set up the bulk copy object using the KeepIdentity option.
Using bulkCopy As SqlBulkCopy = New SqlBulkCopy(connectionString, _
SqlBulkCopyOptions.KeepIdentity)
bulkCopy.BatchSize = 10
bulkCopy.DestinationTableName = "dbo.BulkCopyDemoMatchingColumns"
' Write from the source to the destination.
' This should fail with a duplicate key error
' after some of the batches have already been copied.
Try
bulkCopy.WriteToServer(reader)
Catch ex As Exception
Console.WriteLine(ex.Message)
Finally
reader.Close()
End Try
End Using
' Perform a final count on the destination table
' to see how many rows were added.
Dim countEnd As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Ending row count = {0}", countEnd)
Console.WriteLine("{0} rows were added.", countEnd - countStart)
Console.WriteLine("Press Enter to finish.")
Console.ReadLine()
End Using
End Sub
Private Function GetConnectionString() As String
Throw New NotImplementedException()
End Function
End Module
Performing a Dedicated Bulk Copy Operation in a Transaction
By default, a bulk copy operation is its own transaction. When you want to perform a dedicated bulk copy operation, create a new instance of SqlBulkCopy with a connection string, or use an existing SqlConnection object without an active transaction. In each scenario, the bulk copy operation creates, and then commits or rolls back the transaction.
You can explicitly specify the UseInternalTransaction option in the SqlBulkCopy class constructor to explicitly cause a bulk copy operation to execute in its own transaction, causing each batch of the bulk copy operation to execute within a separate transaction.
Note
Since different batches are executed in different transactions, if an error occurs during the bulk copy operation, all the rows in the current batch will be rolled back, but rows from previous batches will remain in the database.
The following console application is similar to the previous example, with one exception: In this example, the bulk copy operation manages its own transactions. All batches copied up to the point of the error are committed; the batch containing the duplicate key is rolled back, and the bulk copy operation is halted before processing any other batches.
Important
This sample will not run unless you have created the work tables as described in Bulk Copy Example Setup. This code is provided to demonstrate the syntax for using SqlBulkCopy only. If the source and destination tables are located in the same SQL Server instance, it is easier and faster to use a Transact-SQLINSERT … SELECT statement to copy the data.
var connectionString = GetConnectionString();
// Open a sourceConnection to the AdventureWorks database.
using (SqlConnection sourceConnection =
new(connectionString))
{
sourceConnection.Open();
// Delete all from the destination table.
SqlCommand commandDelete = new()
{
Connection = sourceConnection,
CommandText =
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
};
commandDelete.ExecuteNonQuery();
// Add a single row that will result in duplicate key
// when all rows from source are bulk copied.
// Note that this technique will only be successful in
// illustrating the point if a row with ProductID = 446
// exists in the AdventureWorks Production.Products table.
// If you have made changes to the data in this table, change
// the SQL statement in the code to add a ProductID that
// does exist in your version of the Production.Products
// table. Choose any ProductID in the middle of the table
// (not first or last row) to best illustrate the result.
SqlCommand commandInsert = new()
{
Connection = sourceConnection,
CommandText =
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" +
"INSERT INTO " + "dbo.BulkCopyDemoMatchingColumns " +
"([ProductID], [Name] ,[ProductNumber]) " +
"VALUES(446, 'Lock Nut 23','LN-3416');" +
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
};
commandInsert.ExecuteNonQuery();
// Perform an initial count on the destination table.
SqlCommand commandRowCount = new(
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;",
sourceConnection);
long countStart = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Starting row count = {0}", countStart);
// Get data from the source table as a SqlDataReader.
SqlCommand commandSourceData = new(
"SELECT ProductID, Name, ProductNumber " +
"FROM Production.Product;", sourceConnection);
SqlDataReader reader = commandSourceData.ExecuteReader();
// Set up the bulk copy object.
// Note that when specifying the UseInternalTransaction
// option, you cannot also specify an external transaction.
// Therefore, you must use the SqlBulkCopy construct that
// requires a string for the connection, rather than an
// existing SqlConnection object.
using (SqlBulkCopy bulkCopy = new(
connectionString, SqlBulkCopyOptions.KeepIdentity |
SqlBulkCopyOptions.UseInternalTransaction))
{
bulkCopy.BatchSize = 10;
bulkCopy.DestinationTableName =
"dbo.BulkCopyDemoMatchingColumns";
// Write from the source to the destination.
// This should fail with a duplicate key error
// after some of the batches have been copied.
try
{
bulkCopy.WriteToServer(reader);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
reader.Close();
}
}
// Perform a final count on the destination
// table to see how many rows were added.
long countEnd = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Ending row count = {0}", countEnd);
Console.WriteLine("{0} rows were added.", countEnd - countStart);
Console.WriteLine("Press Enter to finish.");
Console.ReadLine();
}
Imports System.Data.SqlClient
Module Module1
Sub Main()
Dim connectionString As String = GetConnectionString()
' Open a sourceConnection to the AdventureWorks database.
Using sourceConnection As SqlConnection = _
New SqlConnection(connectionString)
sourceConnection.Open()
' Delete all from the destination table.
Dim commandDelete As New SqlCommand
commandDelete.Connection = sourceConnection
commandDelete.CommandText = _
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
commandDelete.ExecuteNonQuery()
' Add a single row that will result in duplicate key
' when all rows from source are bulk copied.
' Note that this technique will only be successful in
' illustrating the point if a row with ProductID = 446
' exists in the AdventureWorks Production.Products table.
' If you have made changes to the data in this table, change
' the SQL statement in the code to add a ProductID that
' does exist in your version of the Production.Products
' table. Choose any ProductID in the middle of the table
' (not first or last row) to best illustrate the result.
Dim commandInsert As New SqlCommand
commandInsert.Connection = sourceConnection
commandInsert.CommandText = _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" & _
"INSERT INTO dbo.BulkCopyDemoMatchingColumns " & _
"([ProductID], [Name] ,[ProductNumber]) " & _
"VALUES(446, 'Lock Nut 23','LN-3416');" & _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
commandInsert.ExecuteNonQuery()
' Perform an initial count on the destination table.
Dim commandRowCount As New SqlCommand( _
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;", _
sourceConnection)
Dim countStart As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Starting row count = {0}", countStart)
' Get data from the source table as a SqlDataReader.
Dim commandSourceData As SqlCommand = New SqlCommand( _
"SELECT ProductID, Name, ProductNumber " & _
"FROM Production.Product;", sourceConnection)
Dim reader As SqlDataReader = _
commandSourceData.ExecuteReader()
' Set up the bulk copy object.
' Note that when specifying the UseInternalTransaction option,
' you cannot also specify an external transaction. Therefore,
' you must use the SqlBulkCopy construct that requires a string
' for the connection, rather than an existing SqlConnection object.
Using bulkCopy As SqlBulkCopy = New SqlBulkCopy(connectionString, _
SqlBulkCopyOptions.UseInternalTransaction Or _
SqlBulkCopyOptions.KeepIdentity)
bulkCopy.BatchSize = 10
bulkCopy.DestinationTableName = "dbo.BulkCopyDemoMatchingColumns"
' Write from the source to the destination.
' This should fail with a duplicate key error
' after some of the batches have already been copied.
Try
bulkCopy.WriteToServer(reader)
Catch ex As Exception
Console.WriteLine(ex.Message)
Finally
reader.Close()
End Try
End Using
' Perform a final count on the destination table
' to see how many rows were added.
Dim countEnd As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Ending row count = {0}", countEnd)
Console.WriteLine("{0} rows were added.", countEnd - countStart)
Console.WriteLine("Press Enter to finish.")
Console.ReadLine()
End Using
End Sub
Private Function GetConnectionString() As String
Throw New NotImplementedException()
End Function
End Module
Using Existing Transactions
You can specify an existing SqlTransaction object as a parameter in a SqlBulkCopy constructor. In this situation, the bulk copy operation is performed in an existing transaction, and no change is made to the transaction state (that is, it is neither committed nor aborted). This allows an application to include the bulk copy operation in a transaction with other database operations. However, if you do not specify a SqlTransaction object and pass a null reference, and the connection has an active transaction, an exception is thrown.
If you need to roll back the entire bulk copy operation because an error occurs, or if the bulk copy should execute as part of a larger process that can be rolled back, you can provide a SqlTransaction object to the SqlBulkCopy constructor.
The following console application is similar to the first (non-transacted) example, with one exception: in this example, the bulk copy operation is included in a larger, external transaction. When the primary key violation error occurs, the entire transaction is rolled back and no rows are added to the destination table.
Important
This sample will not run unless you have created the work tables as described in Bulk Copy Example Setup. This code is provided to demonstrate the syntax for using SqlBulkCopy only. If the source and destination tables are located in the same SQL Server instance, it is easier and faster to use a Transact-SQLINSERT … SELECT statement to copy the data.
var connectionString = GetConnectionString();
// Open a sourceConnection to the AdventureWorks database.
using (SqlConnection sourceConnection =
new(connectionString))
{
sourceConnection.Open();
// Delete all from the destination table.
SqlCommand commandDelete = new()
{
Connection = sourceConnection,
CommandText =
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
};
commandDelete.ExecuteNonQuery();
// Add a single row that will result in duplicate key
// when all rows from source are bulk copied.
// Note that this technique will only be successful in
// illustrating the point if a row with ProductID = 446
// exists in the AdventureWorks Production.Products table.
// If you have made changes to the data in this table, change
// the SQL statement in the code to add a ProductID that
// does exist in your version of the Production.Products
// table. Choose any ProductID in the middle of the table
// (not first or last row) to best illustrate the result.
SqlCommand commandInsert = new()
{
Connection = sourceConnection,
CommandText =
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" +
"INSERT INTO " + "dbo.BulkCopyDemoMatchingColumns " +
"([ProductID], [Name] ,[ProductNumber]) " +
"VALUES(446, 'Lock Nut 23','LN-3416');" +
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
};
commandInsert.ExecuteNonQuery();
// Perform an initial count on the destination table.
SqlCommand commandRowCount = new(
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;",
sourceConnection);
long countStart = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Starting row count = {0}", countStart);
// Get data from the source table as a SqlDataReader.
SqlCommand commandSourceData = new(
"SELECT ProductID, Name, ProductNumber " +
"FROM Production.Product;", sourceConnection);
SqlDataReader reader = commandSourceData.ExecuteReader();
//Set up the bulk copy object inside the transaction.
using (SqlConnection destinationConnection =
new(connectionString))
{
destinationConnection.Open();
using (SqlTransaction transaction =
destinationConnection.BeginTransaction())
{
using (SqlBulkCopy bulkCopy = new(
destinationConnection, SqlBulkCopyOptions.KeepIdentity,
transaction))
{
bulkCopy.BatchSize = 10;
bulkCopy.DestinationTableName =
"dbo.BulkCopyDemoMatchingColumns";
// Write from the source to the destination.
// This should fail with a duplicate key error.
try
{
bulkCopy.WriteToServer(reader);
transaction.Commit();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
transaction.Rollback();
}
finally
{
reader.Close();
}
}
}
}
// Perform a final count on the destination
// table to see how many rows were added.
long countEnd = Convert.ToInt32(
commandRowCount.ExecuteScalar());
Console.WriteLine("Ending row count = {0}", countEnd);
Console.WriteLine("{0} rows were added.", countEnd - countStart);
Console.WriteLine("Press Enter to finish.");
Console.ReadLine();
}
Imports System.Data.SqlClient
Module Module1
Sub Main()
Dim connectionString As String = GetConnectionString()
' Open a sourceConnection to the AdventureWorks database.
Using sourceConnection As SqlConnection = _
New SqlConnection(connectionString)
sourceConnection.Open()
' Delete all from the destination table.
Dim commandDelete As New SqlCommand
commandDelete.Connection = sourceConnection
commandDelete.CommandText = _
"DELETE FROM dbo.BulkCopyDemoMatchingColumns"
commandDelete.ExecuteNonQuery()
' Add a single row that will result in duplicate key
' when all rows from source are bulk copied.
' Note that this technique will only be successful in
' illustrating the point if a row with ProductID = 446
' exists in the AdventureWorks Production.Products table.
' If you have made changes to the data in this table, change
' the SQL statement in the code to add a ProductID that
' does exist in your version of the Production.Products
' table. Choose any ProductID in the middle of the table
' (not first or last row) to best illustrate the result.
Dim commandInsert As New SqlCommand
commandInsert.Connection = sourceConnection
commandInsert.CommandText = _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns ON;" & _
"INSERT INTO dbo.BulkCopyDemoMatchingColumns " & _
"([ProductID], [Name] ,[ProductNumber]) " & _
"VALUES(446, 'Lock Nut 23','LN-3416');" & _
"SET IDENTITY_INSERT dbo.BulkCopyDemoMatchingColumns OFF"
commandInsert.ExecuteNonQuery()
' Perform an initial count on the destination table.
Dim commandRowCount As New SqlCommand( _
"SELECT COUNT(*) FROM dbo.BulkCopyDemoMatchingColumns;", _
sourceConnection)
Dim countStart As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Starting row count = {0}", countStart)
' Get data from the source table as a SqlDataReader.
Dim commandSourceData As SqlCommand = New SqlCommand( _
"SELECT ProductID, Name, ProductNumber " & _
"FROM Production.Product;", sourceConnection)
Dim reader As SqlDataReader = _
commandSourceData.ExecuteReader()
' Set up the bulk copy object inside the transaction.
Using destinationConnection As SqlConnection = _
New SqlConnection(connectionString)
destinationConnection.Open()
Using transaction As SqlTransaction = _
destinationConnection.BeginTransaction()
Using bulkCopy As SqlBulkCopy = New _
SqlBulkCopy(destinationConnection, _
SqlBulkCopyOptions.KeepIdentity, transaction)
bulkCopy.BatchSize = 10
bulkCopy.DestinationTableName = _
"dbo.BulkCopyDemoMatchingColumns"
' Write from the source to the destination.
' This should fail with a duplicate key error.
Try
bulkCopy.WriteToServer(reader)
transaction.Commit()
Catch ex As Exception
Console.WriteLine(ex.Message)
transaction.Rollback()
Finally
reader.Close()
End Try
End Using
End Using
End Using
' Perform a final count on the destination table
' to see how many rows were added.
Dim countEnd As Long = _
System.Convert.ToInt32(commandRowCount.ExecuteScalar())
Console.WriteLine("Ending row count = {0}", countEnd)
Console.WriteLine("{0} rows were added.", countEnd - countStart)
Console.WriteLine("Press Enter to finish.")
Console.ReadLine()
End Using
End Sub
Private Function GetConnectionString() As String
Throw New NotImplementedException()
End Function
End Module