--- In firebird-support@yahoogroups.com, "sirhelly74"
<helmut.hartl@f...> wrote:

> A big hello to all experienced users !

Helmut, should unexperienced users modestly go to another room? :)
BTW, when anwsering is something bug in some version or not and what
about future version, it is very convenient to know version which you
use :)
I have'nt at hand just now FB1.5 release build, only experimental
ones LI-V1.5.0.4075 Firebird 1.5 RC7 (already outdated) and
LI-V1.5.1.4354 (in field test stage). On both using your metadata

select a.f1,a.f2,b.f1,b.f2,c.f1,c.f2 from t1 a, t2 b, t3 c
where a.id=b.t1id and b.id =c.t2id
and a.f1 is null and a.f2 is not null

on empty tables reports plan

PLAN JOIN (A INDEX (T1_IDX1),B INDEX (FK_T2),C INDEX (FK_T3))

Perhaps you use ancient engine or long ago did'nt refreshed indices
statistics.

> Or does anyone now how to get the PLAN for a given Select ?

Using isc_dsql_sql_info API call on prepared statement. If you use
Delphi for application development, you can find example of getting
plan in IBSQL unit source.

Best regards,
Alexander.