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

Using the ApachePhoenixDataReader

The ApachePhoenixDataReader retrieves data faster than the ApachePhoenixDataAdapter because it can retrieve data in pages. As you read data from the ApachePhoenixDataReader, 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 [SampleCatalog_1].[SampleSchema_1].SampleTable_1 table:

C#

string connectionString = "URL=http://localhost:8765;";

using (ApachePhoenixConnection connection = new ApachePhoenixConnection(connectionString)) {
  ApachePhoenixCommand cmd = new ApachePhoenixCommand("SELECT * FROM [SampleCatalog_1].[SampleSchema_1].SampleTable_1", connection);
  
  ApachePhoenixDataReader rdr = cmd.ExecuteReader();

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

VB.NET

Dim connectionString As String = "URL=http://localhost:8765;"

Using connection As New ApachePhoenixConnection(connectionString)
  Dim cmd As New ApachePhoenixCommand("SELECT * FROM [SampleCatalog_1].[SampleSchema_1].SampleTable_1", connection)

  Dim rdr As ApachePhoenixDataReader = cmd.ExecuteReader()

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