🚀 go-pugleaf

I have created an application to test asynchronous operations in ADO to 
improve performance of one of my products.  Mostly I'm doing this so that 
the user is able to cancel long-running or runaway queries without having to 
use task manager.

The problem I have is that the cancel operation doesn't appear to be 
cancelling the query at all.  The amount of time that the query I am using 
takes is around 14 seconds.  This same amount of time passes even if I 
attempt to cancel the query.  As tests I have used a longer running query 
and reduced the CommandTimeout of both the command and the connection 
without a change in results.  I also tried all combinations of the 
eoAsyncXXX options in TADOCommand::ExecuteOptions (aside from the starting 
point which I mention below).

Configuration
------------
I added a TADOConnection to the form and set ConnectOptions to 
[coAsyncConnect].  I am using an Oracle 10G connection at my office (using 
an Oracle OLEDB driver on my computer).  I added a TADOCommand to the form 
and set ExecuteOptions to [eoAsyncExecute].  I added a TEdit to specify a 
SQL statement and a TMemo which receives status information.  I added a 
TButton which executes the command or, if a command is executing, cancels a 
command:

  if (ADOCommand1->States.Contains(stExecuting))
  {
    Memo1->Lines->Add("Cancelling ...");
    Memo1->Refresh();
    ADOCommand1->Cancel();
    Memo1->Lines->Add("Cancelled");
    return;
  }

  ADOCommand1->CommandText = Edit1->Text;
  ADOCommand1->Execute();

  Memo1->Lines->Add("Executing ...");

So here is what I need to know.  Have I configured my test correctly to use 
asynchronous ADO?  Is Cancel() always a blocking operation?  Is Cancel() 
optionally supported by the database?  If the query is a runaway query 
should Cancel() eventually come back?

I have performed some general archive searches on this subject.  I found a 
few cases where the authors mentioned that Cancel() has a long delay but 
none of them mentioned that it was the same amount of time as the normal 
running query.  Most other posts I found were simply questions regarding how 
to cancel long running queries.  The answer in those cases was to use 
asynchronous ADO.

Thank you for any insight,

- Clayton