> Why is there any DISTINCT at all in this statement? When using UNION, it
> is implicitly distinct, if you don't want things to be distinct, you have
> to use UNION ALL.
>
> If you remove all three DISTINCTs, the result should be the same, the only
> exception being that it also works on Firebird 1.5.
>
> Though that was from my SQL perspective, I've no clue about the IBO
> perspective (so you might still get an overflow).

I didn't realize earlier versions of Firebird would break as a result of
that SQL statement. I have fixed this immediately and it will be in the next
release.

I cannot say why there was a stack overflow when it was modified as the
results of the query should indeed be the same as Set points out.

I already made the change and I get no stack overflow condition.

Regards,
Jason LeRoy Wharton
www.ibobjects.com