One thing that I always see when FB optimizer comes into the talk is
that nobody *exactly* know how the optimizer works. I would sugest to
FF pay someone to study and write a very good documentation about it,
or even rewrite it entirely to make it smarter.

As Dmitry said, this is one area where FB looses almost to any other
SGBD out there. Fortunatelly, even with all the mess, Arno did very
good improvements on it since FB 1.5

Carlos
http://www.warmboot.com.br
FireBase - http://www.FireBase.com.br



ABS> The 3 above queries are very similar, the last two uses left joins, the
ABS> first one inner joins, the first plan is perfect, the last 2 bad ones.

ABS> Hope this finding can help.

ABS> thank you very much !

ABS> --

ABS> Alexandre Benson Smith