How to use SqlFileStream for transactional access to SQL Server 2012 FileTable? - sql

Question

I'm trying to use the SqlFileStream object in a WCF service to get a handle to a specific file that is in a SQL Server 2012 FileTable. I'm able to get the path and transaction context like you would expect with no issues using this piece of code:
using (SqlConnection con2 = new SqlConnection(ConfigurationManager.ConnectionStrings["FileStorage"].ConnectionString))
{
con2.Open();
string getFileHandleQuery = String.Format(
#"SELECT FileTableRootPath(), file_stream.GetFileNamespacePath(), GET_FILESTREAM_TRANSACTION_CONTEXT()
FROM {0}
WHERE stream_id = #streamId", "FSStore");
byte[] serverTransactionContext;
string serverPath;
using (SqlCommand sqlCommand = new SqlCommand(getFileHandleQuery, con2))
{
sqlCommand.Parameters.Add("#streamId", SqlDbType.UniqueIdentifier).Value = new Guid(finalFileHandleStreamId);
using (SqlDataReader sqlDataReader = sqlCommand.ExecuteReader())
{
sqlDataReader.Read();
serverPath = String.Concat(sqlDataReader.GetSqlString(0).Value, sqlDataReader.GetSqlString(1).Value);
serverTransactionContext = sqlDataReader.GetSqlBinary(2).Value;
sqlDataReader.Close();
}
}
con2.Close();
}
However, once I try and actually use the path and transaction context to create a new SqlFileStream:
using (SqlFileStream dest =
new SqlFileStream(serverPath, serverTxn, FileAccess.Write))
{
...
}
The above blows ups with the following exception: The mounted file system does not support extended attributes.
Can someone please explain to me what I'm doing wrong here?
Thanks!

Answer 1

If you are trying to use FileTable and receive an error when new a SqlFileStream object, please check the filePath value.
SqlFileStream sfs = new SqlFileStream(filePath, objContext, System.IO.FileAccess.Read); <-- Error "The mounted file system does not support extended attributes"
Correct way to obtain the filePath value is
SELECT [file_stream].PathName() FROM dbo.fTable WHERE name = 'test.xlsx'
filePath value should look like:
\\HOSTNAME\MSSQLSERVER\v02-A60EC2F8-2B24-11DF-9CC3-AF2E56D89593\test\dbo\fTable\file_stream\A654465D-1D9F-E311-B680-00155D98CA00\VolumeHint-HarddiskVolume1
not like:
\\HOSTNAME\MSSQLSERVER\Store\fDirectory\test.xlsx
That is required by design. Please refer to
https://connect.microsoft.com/SQLServer/feedback/details/729273/sql-server-denali-filetable-access-using-sqlfilestream-returns-error-the-mounted-file-system-does-not-support-extended-attributes
and
Access FILESTREAM Data with OpenSqlFilestream
http://technet.microsoft.com/en-us/library/bb933972.aspx