What could be the reasons for not allowing Cartesian Product in a Universe Design?
Thanks,
Vinay.
Listserv Archives (BOB member since 2002-06-25)
If you allow a Cartesian product, a user could inadvertently create a query (with an out of date universe, for example) that could process for hours and retrieve hundreds of thousands of rows. This is a situation you want to avoid and therefore argues for not allowing a Cartesian product in the universe.
George Baranowski
QuadraMed
Listserv Archives (BOB member since 2002-06-25)
Let’s say you have two tables, one with 127,000 rows, the other with 22,000. If you join these together and a cartesian product exists you get the product of the tables selected. In this example you would return 2,794,000,000 rows of data!
Greg
2B||!2B
From: Rao, Vinay (GEP, Contractor) [SMTP:Vinay.Rao@GEPEX.GE.COM] Sent: Friday, March 03, 2000 2:15 PM
What could be the reasons for not allowing Cartesian Product in a Universe Design?
Listserv Archives (BOB member since 2002-06-25)
Vinay,
The Cartesian Product definition for a RDBMS is different from the BO Definition of Cartesian product.
I have set my universe in designer where I just ’ WARN’ about the cartesian product . I have few objects in universe where I use more than one table in select as shown below :
sum(float(((table1.BL_CCY_ACT_7_CM) * (table2.CT_DY_CDAR_PM_YTD +7)) - ((table1.BL_CCY_ACT_0_CM) * table2.CT_DY_CDAR_PM_YTD)) /7)
When I try to run the query I get a warning message from BO about cartesian product,but the result is
always correct.
So, if you have similar situation, don’t bother about the cartesian product.
Hope it helps!!
-Durgesh
What could be the reasons for not allowing Cartesian Product in a Universe Design?
Thanks,
Vinay.
Listserv Archives (BOB member since 2002-06-25)
I disagree with durgesh.
If you look at the SQL you will realize that cartesian product is after all the same cartesian product as in RDBMS.
Durgesh must be having a table which has just 1 row in it. So even if its a cartesian product he gets the correct result .
The point is…
Check the SQL being generated and look at the joins.
Ashish
Listserv Archives (BOB member since 2002-06-25)
Ashish,
You are correct that I included a where condition in such a way that I select only one row from the second table and
BusinessObjects has no way of knowing it.
Regards,
Durgesh
I disagree with durgesh.
If you look at the SQL you will realize that cartesian product is after all the same cartesian
product as in RDBMS.
Durgesh must be having a table which has just 1 row in it. So even if its a cartesian product he gets
the correct result
Listserv Archives (BOB member since 2002-06-25)