Questions on SQL executed by Answers about Row_number

Question

While debugging from the log file of sql executed by OBIEE Answers, I found the following sql statements:
-------------------- Sending query to database named DW_TESTING (id: <<10886>>):
select D1.c2 as c1,
D1.c3 as c2,
D1.c1 as c3
from
(select D1.c1 as c1,
D1.c2 as c2,
D1.c3 as c3
from
(select sum(T1113.PRODUCT_SALES) as c1,
T1141.YEAR as c2,
T1141.QUARTER as c3,
ROW_NUMBER() OVER (PARTITION BY T1141.QUARTER ORDER BY T1141.QUARTER ASC) as c4
from
DWADMIN.DATE_MASTER T1141,
DWADMIN.DAILY_SALES T1113
where ( T1113.SALES_DATE = T1141.CALENDAR_DATE )
group by T1141.YEAR, T1141.QUARTER
) D1
where ( D1.c4 = 1 )
) D1
order by c2
+++Administrator:2e0000:2e0005:----2009/06/10 15:37:11
-------------------- Sending query to database named DW_TESTING (id: <<10931>>):
select D2.c2 as c1,
D2.c3 as c2,
D2.c1 as c3
from
(select D1.c1 as c1,
D1.c2 as c2,
D1.c3 as c3
from
(select sum(T620.PRODUCT_SALES) as c1,
T1141.YEAR as c2,
T1141.QUARTER as c3,
ROW_NUMBER() OVER (PARTITION BY T1141.QUARTER ORDER BY T1141.QUARTER ASC) as c4
from
DWADMIN.DATE_MASTER T1141,
BEADMIN.BE_DAILY_SALES T620
where ( T620.SALES_DATE = T1141.CALENDAR_DATE )
group by T1141.YEAR, T1141.QUARTER
) D1
where ( D1.c4 = 1 )
) D2
order by c2
Does anyone know why the Answers will filter the ROW_NUMBER = 1? I wonder how come the Answers run 2 different SQL statement instead of one.
My environment:
2 Fact tables
3 common dimensions + 1 dimension which can only join with one of the fact table
2 fact tables does not directly join together.
This problem is found whenever I choose any columns from both 2 fact tables. If columns are only from either one fact table, the results are correct.
Thx all ~

Answer 1

Wildmight,
May I ask what should I check for 'content tab' you mentioned?
Also for the time dimension, I did not check "time dimension" box in the timeDimension hierarchy property. Infact is that we MUST set the time dimension as "Time Dimension" in the property? What is the difference? I remembered I have tried to set it and assign the "Year" as the chronical key, but the problem remains.
Finally, I do not set any filters. That's why I wonder when I saw the Answers Engine has filtered the Row_number by c1 = 1.
Thanks a lot ~