Adam wrote:

>
> ... If the query was written correctly,
> then there would have been no problems

If all queries were written correctly, there would be no need for an
optimizer. The goal of the optimizer is to make up for imperfect
queries ... which requires some imagination of what a less than perfect
query might look like. Firebird is reasonably good at handling inner
joins. For this query, we could turn outer joins that depend on a
non-null value in the outer table into inner joins... Then there's the
trick of inverting IN's...

Regards,


Ann