Re: Detecting when outer joins are needed

[Andrus Adamchik <an...@objectstyle.org>]

-1.

My argument still stands - unless a user tells us what (s)he wants to  
do, there is no good way to guess it. Ok, we've even identified a few  
specific cases. But we still can't guess it in a general case.  
Changing the algorithm without understanding it is asking for trouble.

> Also, how do I know that I've got the complete list of gotchas?

How do you know that we have it handled correctly in Cayenne ? ;-)  
That's my point exactly - this requires analysis - Cayenne can't do  
it automagically.

Andrus


On Aug 28, 2006, at 9:54 AM, Øyvind Harboe wrote:

> On 8/25/06, Andrus Adamchik <an...@objectstyle.org> wrote:
>>
>> On Aug 23, 2006, at 11:35 PM, Mike Kienenberger wrote:
>>
>> > Here's where I'm finding that I need outer joins:
>> >
>> > 1) If two qualifiers for a non-mandatory relationship path are or'd
>> > together.   This is also what Øyvind Harboe reported.   It may  
>> be that
>> > the non-mandatory part is irrelevent.
>> >
>> > 2) If using noMatchExp on a non-null value for a non-mandatory
>> > relationship path.
>>
>> Thanks Mike - that makes sense. I think "non mandatory" part is
>> relevant. Not sure that we need to catch it though. IMO this should
>> be left as an exercise to the user.
>
> I could really do with having this exercise clearly formulated in  
> doc/wiki...
>
> I have a hard time explaining my peers what precisely it is that they
> should be looking for.
>
> Also, how do I know that I've got the complete list of gotchas?
>
> Is it in theory possible to detect this during runtime?
>
> It would be nice to be able to add some runtime checks that generated
> expressions aren't running into this problem.
>
> -- 
> Øyvind Harboe
> http://www.zylin.com
>

Re: Detecting when outer joins are needed

[Øyvind Harboe <oy...@zylin.com>]

> > Also, how do I know that I've got the complete list of gotchas?
>
> How do you know that we have it handled correctly in Cayenne ? ;-)
> That's my point exactly - this requires analysis - Cayenne can't do
> it automagically.

I see. Documentation here (even more so than usually) will be greatly
appreciated.


-- 
Øyvind Harboe
http://www.zylin.com