When does OBIEE forcibly use Subquery Factoring ?

Question

In a 10.2 "datawarehouse" schema I see OBIEE queries of the form :
WITH  SAWITH0 AS (select distinct T12345.COLUMN_1 as c1 from       DIMENSION_TABLE T12345
                  where  ( T12345.COLUMN_1 like 'HEMANT%')
) select distinct SAWITH0.c1 as c1 from       SAWITH0I cannot understand why OBIEE wouldn't run a simpler
select distinct T12345.COLUMN_1 as c1 from       DIMENSION_TABLE T12345
where  ( T12345.COLUMN_1 like 'HEMANT%')What OBIEE setup would cause even simple queries to be generated as using Subquery Factoring ?
Hemant K Chitale
http://hemantoracledba.blogspot.com

Answer 1

Hi Hemant,
use of WITH can be disabled in the OBIEE RPD Connection pool. Its enabled by default to allow the performance benefit you would see when using aggregated result sets. I personally think the OBIEE server is simply not advanced enough to determine when it doesn't need to use it (ie when selecting distinct dimension member values in dashboard prompts).
Just my 2c. Hopefully some of the experianced users on here can expand a little more for you. Id be interested to know as well.