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

Using the PostgreSQLDataReader

The PostgreSQLDataReader retrieves data faster than the PostgreSQLDataAdapter because it can retrieve data in pages. As you read data from the PostgreSQLDataReader, 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 "postgres"."schema01".Orders table:

C#

string connectionString = "User=postgres;Password=admin;Database=postgres;Server=127.0.0.1;Port=5432";

using (PostgreSQLConnection connection = new PostgreSQLConnection(connectionString)) {
  PostgreSQLCommand cmd = new PostgreSQLCommand("SELECT * FROM \"postgres\".\"schema01\".Orders", connection);
  
  PostgreSQLDataReader rdr = cmd.ExecuteReader();

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

VB.NET

Dim connectionString As String = "User=postgres;Password=admin;Database=postgres;Server=127.0.0.1;Port=5432"

Using connection As New PostgreSQLConnection(connectionString)
  Dim cmd As New PostgreSQLCommand("SELECT * FROM \"postgres\".\"schema01\".Orders", connection)

  Dim rdr As PostgreSQLDataReader = cmd.ExecuteReader()

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