The CData ADO.NET Provider for Azure Data Lake Storage implements two ADO.NET interfaces you can use to retrieve data from Azure Data Lake Storage: ADLSDataAdapter and ADLSDataReader objects. Whereas ADLSDataAdapter objects retrieve a single result set of all the data that matches a query, ADLSDataReader objects fetch data in subset increments as needed.

Using the ADLSDataReader

The ADLSDataReader retrieves data faster than the ADLSDataAdapter because it can retrieve data in pages. As you read data from the ADLSDataReader, it periodically requests the next page of results from the data source, if required. This causes results to be returned at a faster rate. The following example selects all the columns from the Resources table:

C#

string connectionString = "Account=MyStorageAccount;FileSystem=MyBlobContainer;AccessKey=myAccessKey;";

using (ADLSConnection connection = new ADLSConnection(connectionString)) {
  ADLSCommand cmd = new ADLSCommand("SELECT * FROM Resources", connection);
  
  ADLSDataReader rdr = cmd.ExecuteReader();

  while (rdr.Read()) {
    Console.WriteLine(String.Format("\t{0} --> \t\t{1}", rdr["FullPath"], rdr["Permission"]));
  }
}

VB.NET

Dim connectionString As String = "Account=MyStorageAccount;FileSystem=MyBlobContainer;AccessKey=myAccessKey;"

Using connection As New ADLSConnection(connectionString)
  Dim cmd As New ADLSCommand("SELECT * FROM Resources", connection)

  Dim rdr As ADLSDataReader = cmd.ExecuteReader()

  While rdr.Read()
    Console.WriteLine([String].Format(vbTab & "{0} --> " & vbTab & vbTab & "{1}", rdr("FullPath"), rdr("Permission")))
  End While
End Using