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

Using the AvroDataReader

The AvroDataReader retrieves data faster than the AvroDataAdapter because it can retrieve data in pages. As you read data from the AvroDataReader, 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 SampleTable_1 table:

C#

string connectionString = "URI=C:\folder\table.avro;";

using (AvroConnection connection = new AvroConnection(connectionString)) {
  AvroCommand cmd = new AvroCommand("SELECT * FROM SampleTable_1", connection);
  
  AvroDataReader rdr = cmd.ExecuteReader();

  while (rdr.Read()) {
    Console.WriteLine(String.Format("\t{0} --> \t\t{1}", rdr["Id"], rdr["Column1"]));
  }
}

VB.NET

Dim connectionString As String = "URI=C:\folder\table.avro;"

Using connection As New AvroConnection(connectionString)
  Dim cmd As New AvroCommand("SELECT * FROM SampleTable_1", connection)

  Dim rdr As AvroDataReader = cmd.ExecuteReader()

  While rdr.Read()
    Console.WriteLine([String].Format(vbTab & "{0} --> " & vbTab & vbTab & "{1}", rdr("Id"), rdr("Column1")))
  End While
End Using