Subject From where Firebird get field values in ORDER BY if DISTINCT is applied
Author liviuslivius
Post date 2015-08-13T08:16:54Z
Hi,
 
query like this
 
SELECT DISTINCT T.FIELD_1 FROM TEST T ORDER By T.FIELD_2, T.FIELD_1
 
from where Firebird get info about T.FIELD_2 in order by if it applied first DISTINCT (unique sort)?
 
i run this also on FB3 to get more info from explained plan
 
Select Expression
    -> Sort (record length: 32, key length: 16)
        -> Unique Sort (record length: 32, key length: 8)
            -> Table "TEST " as "T" Full Scan
 
Is this a bug? Because first FB sort unique results and got only unique values of FIELD_1 and it can not know what value is in FIELD_2 after unique sort.
 
 
regards,
Karol Bieniaszewski