Hmm, good!

Then try these two:

select <skipped many fields>,
(select t2a.SPC from TBL_2 t2a where t2a.TBL1ID=TBL_1.ID
and not exists(select * from TBL_2 t2b where t2b.TBL1ID=t2a.TBL1ID
and t2b.KOD+0 < t2a.KOD)) FIRST_SPECDATA,
(select count(TBL_2.ID) from TBL_2 where TBL_2.TBL1ID=TBL_1.ID)
SPECDATA_COUNT
from TBL_1
where TBL_1.ID>0
and TBL_1.SMALL_FLD1>0
or 2=0
order by TBL_1.STRING_FLD2

and

select <skipped many fields>,
(select first 1 TBL_2.SPC from TBL_2 where TBL_2.TBL1ID=TBL_1.ID
order by TBL_2.KOD+0) FIRST_SPECDATA,
(select count(TBL_2.ID) from TBL_2 where TBL_2.TBL1ID=TBL_1.ID)
SPECDATA_COUNT
from TBL_1
where TBL_1.ID>0
and TBL_1.SMALL_FLD1>0
or 2=0
order by TBL_1.STRING_FLD2

Even though I expect KOD to be unique in TBL_2, I think it may slow down your
queries (at least I suspect it to be guilty of slowing down the one I wrote,
that's why I said 'good' above).

But what's the output of this query? Does the select count return a high number?

Report back again,
Set

--- In firebird-support@yahoogroups.com, "Sandor Szollosi" wrote:
> Thank you Set,
>
>
> It takes 44 sec.
>
> Plan
> PLAN SORT ((TBL_1 NATURAL))
> PLAN (T2A INDEX (FK_TBL2_TBL1ID))
> PLAN (T2B INDEX (FK_TBL2_TBL1ID,UN_TBL2_ID))
> PLAN (TBL_2 INDEX (FK_TBL2_TBL1ID))