Derby and handling of exceptions / errors

[Daniel Noll <da...@nuix.com>]

Hi all.

I've noticed that Derby appears to be catching Throwable somewhere 
internally, and thus is absorbing exceptions which should normally not 
be caught.  This means that ultimately the user isn't seeing the correct 
exception as it is claiming a problem with the database where they 
really should be seeing the error dialog about the system being out of 
memory.

I can do this:

   try {
     connection.prepareStatement(...).executeQuery()...
   } catch (SQLException e) {
     if (e.getCause() instanceof Error) {
       throw (Error) e.getCause();
     } else if ...
   }

This appears to catch situations I'm seeing in the logs, but is it okay 
to assume that the OOMEs and such will only be one level deep inside the 
exception hierarchy?

Daniel


-- 
Daniel Noll                            Forensic and eDiscovery Software
Senior Developer                              The world's most advanced
Nuix                                                email data analysis
http://nuix.com/                                and eDiscovery software

Re: Derby and handling of exceptions / errors

[Rick Hillegas <Ri...@Sun.COM>]

Hi Daniel,

I don't think that this part of the Derby api is specified. I don't 
think we have any regression tests in place to guarantee that the 
position of the original error in the exception graph won't change 
across releases. Bear in mind that SQLExceptions have their own chaining 
mechanism. So when you unravel the exception ball, you have to follow 
both SQLException.getNextException() and Throwable.getCause(). I would 
expect the original error to be at the end of some trajectory through 
the exception graph. You may need to write an acceptance test for your 
application to alert you if Derby's behavior changes across releases.

Hope this helps,
-Rick

Daniel Noll wrote:
> Hi all.
>
> I've noticed that Derby appears to be catching Throwable somewhere 
> internally, and thus is absorbing exceptions which should normally not 
> be caught.  This means that ultimately the user isn't seeing the 
> correct exception as it is claiming a problem with the database where 
> they really should be seeing the error dialog about the system being 
> out of memory.
>
> I can do this:
>
>   try {
>     connection.prepareStatement(...).executeQuery()...
>   } catch (SQLException e) {
>     if (e.getCause() instanceof Error) {
>       throw (Error) e.getCause();
>     } else if ...
>   }
>
> This appears to catch situations I'm seeing in the logs, but is it 
> okay to assume that the OOMEs and such will only be one level deep 
> inside the exception hierarchy?
>
> Daniel
>
>