Hello,

this is my query :

Select
MAINTABLE.ID
from
MAINTABLE
Join SECONDTABLE on SECONDTABLE.ID_obj=MAINTABLE.ID_obj
Join THIRDTABLE on THIRDTABLE.ID_obj=MAINTABLE.ID_obj
where
(MAINTABLE.name = 'jean' or
SECONDTABLE.name = 'jean' or
THIRDTABLE.name = 'jean')

I have an index on

MAINTABLE.name
SECONDTABLE.name
THIRDTABLE.name

the probleme is that firebird use

PLAN JOIN (THIRDTABLE NATURAL, SECONDTABLE INDEX (RDB$PRIMARY436), MAINTABLE INDEX (RDB$PRIMARY26))

and it not use the index of the field
MAINTABLE.name
SECONDTABLE.name
THIRDTABLE.name

:(