It looks like two emails got intermixed when flowing through internet ... ???

The copy I got starts with:

> I'm facing serious speed issues with FB2.0, where the optimizer
> follows a different path than the one used by FB1.5.

but later it states that:

> Both the 1.5 and the 2.0 optimizers select a NATURAL scan of the table.

So, are the plans the same or different ?

Then there is written:

> As soon as I heard about 2.0.1 (and in particular about
> http://tracker.firebirdsql.org/browse/CORE-1029), I retried my
> attempts on that version as well, but nothing changed.

which points to bug "Bad plan in outer joins with IS NULL clauses",
but in the attached script there are no outer joins, in fact
there are no joins at all.

> FOR SELECT what
> FROM testbes tb
> WHERE tb.id = :p_id
> AND tb.dat = :p_dat
> INTO what DO
> SUSPEND;

Ivan