Calling Stored Procedures
You can invoke a stored procedure using HDFSCommand in the same way as any other SQL stored procedure. To instantiate a HDFSCommand object, provide the name of the stored procedure and a HDFSConnection instance as arguments to the constructor. Set the value of the CommandType property to "StoredProcedure" and add the parameters as key-value pairs to the Parameters collection of the HDFSCommand instance.
C#
string connectionString = "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;"; using (HDFSConnection connection = new HDFSConnection(connectionString)) { HDFSCommand cmd = new HDFSCommand("Open", connection); cmd.CommandType = CommandType.StoredProcedure; cmd.Parameters.Add(new HDFSParameter("@Path", "/user/root/test/new.txt")); // Add other parameters as needed ... HDFSDataReader rdr = cmd.ExecuteReader(); while (rdr.Read()) { for (int i = 0; i < rdr.FieldCount; i++) { Console.WriteLine(rdr.GetName(i) + " --> " + rdr[i]); } Console.WriteLine(); } }
VB.NET
Dim connectionString As String = "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;" Using connection As New HDFSConnection(connectionString) Dim cmd As New HDFSCommand("Open", connection) cmd.CommandType = CommandType.StoredProcedure cmd.Parameters.Add(New HDFSParameter("@Path", "/user/root/test/new.txt")) ' Add other parameters as needed ... Dim rdr As HDFSDataReader = cmd.ExecuteReader() While rdr.Read() For i As Integer = 0 To rdr.FieldCount - 1 Console.WriteLine(rdr.GetName(i) + " --> " + rdr(i)) Next Console.WriteLine() End While End Using
Alternatively, you can set the parameters of a stored procedure in the text of the command. The support for stored procedure statements follows the standard form shown below:
"EXECUTE my_proc @first = 1, @second = 2, @third = 3;" "EXEC my_proc @first = 1, @second = 2, @third = 3;"
To execute a parameterized query, add parameters as key-value pairs to the Parameters collection of the HDFSCommand instance.
C#
string connectionString = "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;"; using (HDFSConnection connection = new HDFSConnection(connectionString)) { HDFSCommand cmd = new HDFSCommand("EXECUTE Open Path = @Path;", connection); cmd.Parameters.Add(new HDFSParameter("@Path", "/user/root/test/new.txt")); // Add other parameters as needed ... HDFSDataReader rdr = cmd.ExecuteReader(); while (rdr.Read()) { for (int i = 0; i < rdr.FieldCount; i++) { Console.WriteLine(rdr.GetName(i) + " --> " + rdr[i]); } Console.WriteLine(); } }
VB.NET
Dim connectionString As String = "Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;" Using connection As New HDFSConnection(connectionString) Dim cmd As New HDFSCommand("EXECUTE Open Path = @Path;", connection) cmd.Parameters.Add(New HDFSParameter("@Path", "/user/root/test/new.txt")) ' Add other parameters as needed ... Dim rdr As HDFSDataReader = cmd.ExecuteReader() While rdr.Read() For i As Integer = 0 To rdr.FieldCount - 1 Console.WriteLine(rdr.GetName(i) + " --> " + rdr(i)) Next Console.WriteLine() End While End Using