With_clause_supported

Hello,
We are using 10.1.3.1.1 and oracle 10g.
Please let us know the advantages of checking the WITH_clause_supported in the features section of the database in the physical layer.
Is it better to use this clause or not.
Thanks,
Vinutha

Hi,
The when we use the WITH clause it actually returns the output of the query in the with clause and stores it in temporary memory location. So when you fire the same query again it doesn't hit the physical data source rather it fetch the data from the tempoarary memory. Which enhances the performance. This is quite similar to the concept of caching. So depending upon your requirement you can use the with clause.

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Report with multiplying columns and WITH clause

Hello
I saw sth strange in my report. I assume that it could happens very often.
I have report with few columns which two of them ar most complicated (many joins subqueries aggreagations on joined values etc.) These two columns (i.e C3,C4) should be multiplied (C3*C4).
When i do pure report without multiplying only columns C1,C2,C3,C4 everything is ok - duration about 15 sec. but... when I put next column on report which multiply these columns (in Answers C5=C3*C4)
I wait 3-4 minutes and my database hungs :(. After investigation I saw that in first case to databese goes pure "SELECT" statement it means:
"Select ... as C1, ... as C2, max(...) as C3, sum(xxx)... C4 from yyy,sss,ttt WHERE aaa"
but in second case BI uses WITH clause it means:
WITH SAWITH0 AS
( Select ... as C1, ... as C2, max(...) as C3, sum(xxx)... C4 from yyy,sss,ttt WHERE aaa )
SELECT SAWITH0.C1 as C1,
SAWITH0.C2 as C2,
     SAWITH0.C3 as C3,
     SAWITH0.C4 as C4,
     SAWITH0.C3*SAWITH0.C4 as C5 FROM SSS
and this statement is long runninq query and kills my database :(.
I checked that SQL like this:
Select ... as C1, ... as C2, max(...) as C3, sum(xxx)... C4, max(...)*sum(xxx)... As C5 from yyy,sss,ttt WHERE aaa" -
runs few times faster than that above
I know that I can do this multiply in business model layer but sometimes users can multiply(or other operations) on columns in reports without my knowledge and it kills my db :(. Where is bug? Why SQLs with WITH clause takes so much db time?
Thank you for each kind of help

WITH clause or Subquery Factoring allows the set of data to be reused multiple times within the SQL. Oracle will usually materialize the data into a temporary table (you will see it if you take an explain plan of the SQL).
I would be surprised if it was the actual WITH clause that was causing the performance issue, however you can test this by turning the WITH clause feature off. Go to the Physical model, right mouse click on your Database > Properties > Features Tab, scroll down to WITH_CLAUSE_SUPPORTED and switch it off.
I'd be interested to know if you do see actual improvement.
Good Luck.

OBIEE 11g "WITH SAWITH0 AS" subquery factoring clause in the generated sql

I've observed that the OBIEE 11g generates in the query log physical query using the WITH (sub-query factoring) clause to make the generated sql elegantly readable. This is great! Thanks for the developers. However I have some questions about this.
__Background__
Oracle Database' default behaviour is that if you have only one sub-query in the WITH section, it executes it as an in-line view and does not materialize it before the main sql is executed. If you have more than one, by default the database engine materializes all of them in the order of the definition. In some cases this can completely blow up the SGA and make the query never ending. To divert this behaviour you can apply two hints that work both in inline views and in sub-queries as well: /*+ MATERIALIZE */ and /*+ INLINE*/, however Analytics 11g does not seem to have hint capabilities at the logical table level, only at physical table level.
If we go with the current defaults, developers not aware of this feature can bump into serious performance issues for the sake of some syntax candy at the generated sql level, I'm afraid.
__Questions__
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The WITH statement is not added to make the query more elegant, it's added for performance reasons. If your queries take long to run then you may have a design issue. In a typical DWH DB SGA needs to be seriously increased since the queries ran are much larger and complex than on an OLTP DB. In any case you can disable the WITH statement in the Admin Tool by double clicking on your database object on the physical layer and going to the Features tab. The feature is called WITH_CLAUSE_SUPPORTED.

Issue with ROW_NUMBER() OVER (PARTITION)

Hi,
Please read the Thread completely, I have created a Report to see Yearly Turnover%, The report works fine but when I take Quarter and Months in it, it restricts the result to only 1 line(i.e., my first year's Turnover) and when I opened the Physical query, I saw the BI Server is using
ROW_NUMBER() OVER (PARTITION BY)
which is not at all necessary.
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thanks in Advance,
Anand

You said 'it restricts the result to only 1 line' means the value is nor drill down to next level?
In that case Yearly Turnover% is set to Year level?

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Message was edited by:
Tony Miller

WITH clause or Subquery Factoring allows the set of data to be reused multiple times within the SQL. Oracle will usually materialize the data into a temporary table (you will see it if you take an explain plan of the SQL).
I would be surprised if it was the actual WITH clause that was causing the performance issue, however you can test this by turning the WITH clause feature off. Go to the Physical model, right mouse click on your Database > Properties > Features Tab, scroll down to WITH_CLAUSE_SUPPORTED and switch it off.
I'd be interested to know if you do see actual improvement.
Good Luck.

With_clause_supported

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