Question

I am trying to change the timeout for a SqlCommand query, in a method that tests my connection for a given connection string. The code is similar to this:

using (SqlConnection connection = new SqlConnection(connectionString))
    {
      SqlCommand cmd = new SqlCommand("SELECT ...", connection);
      cmd.CommandTimeout = 10;
      connection.Open();
      SqlDataReader reader = cmd.ExecuteReader();
      ...
      connection.Close();
    }

I would like to have a short timeout here, since I just want to test if this connection string is okay.
But, no matter what number I set on CommandTimeout (I tried 0, 1, 2, 4, 10, 30, 60, 120), my real time obtained for a dummy connection string is always about the same (total running time of about 15 seconds).

So, seems to me that the value I set on CommandTimeout is being ignored for some reason.

Any ideas why?

Answer 1

I think you’re confusing what exactly SqlCommand.CommandTimeout is for. As per this MSDN reference:

Gets or sets the wait time before terminating the attempt to execute a command and generating an error.

In your case, you are executing a DataReader and stepping through your query (whatever it may be). It is taking minimal time for each Read() which is why you wouldn’t be hitting your timeout.

Edit:

If you are using a wrong connection string, your Timeout will not be the Command timeout, but it’ll be the Connection time. This defaults to 15 seconds. That is the timeout that is effective in your situation.

You’re going to timeout on the method call SqlConnection.Open(), not SqlCommand.ExecuteReader(). Therefore the ConnectionTimeout property is going to be the effective timeout value.

SqlConnection.ConnectionTimeout Property MSDN Reference