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

Using the ElasticsearchDataAdapter

Use the adapter's Fill method to retrieve data from the data source. An empty DataTable instance is passed as an argument to the Fill method. When the method returns, the DataTable instance is populated with the queried data. Note that the ElasticsearchDataAdapter is slower than the ElasticsearchDataReader because the Fill method needs to retrieve all data from the data source before returning.

The following example selects the Id and Name columns of the Employee table:

C#

string connectionString = "Server=127.0.0.1;Port=9200;";

using (ElasticsearchConnection connection = new ElasticsearchConnection(connectionString)) {
  ElasticsearchDataAdapter dataAdapter = new ElasticsearchDataAdapter(
  "SELECT Id, Name FROM [CData].[Elasticsearch].Employee", connection);

  DataTable table = new DataTable();
  dataAdapter.Fill(table);

  Console.WriteLine("Contents of Employee.");

  foreach (DataRow row in table.Rows) {
    Console.WriteLine("{0}: {1}", row["Id"], row["Name"]);
  }
}

VB.NET

Dim connectionString As String = "Server=127.0.0.1;Port=9200;"

Using connection As New ElasticsearchConnection(connectionString)
  Dim dataAdapter As New ElasticsearchDataAdapter("SELECT Id, Name FROM [CData].[Elasticsearch].Employee", connection)

  Dim table As New DataTable()
  dataAdapter.Fill(table)

  Console.WriteLine("Contents of Employee.")

  For Each row As DataRow In table.Rows
    Console.WriteLine("{0}: {1}", row("Id"), row("Name"))
  Next
End Using