Problem with fan Trap.

[Former Member]

Hi all,

I am having a problem resolving fan trap.

I am having a universe build over a MY SQL database.

The universe totaly consists of 4 tables and are related in the following way.

"A one to many B one to many C many to one D"

There are many 1-may joins between A and B and also between B and C.

There are measures and dimensions in A, B. And in C there are only measureas and 1 dimension.

When I pull the objects from all the three tables (A,B and C) there is a fan trap occuring and the values are getting inflated.

So I created an alias for B and defined a context for A, B and B alias and A,B and C. I have also checked the option of "Multiple SQL statements for different contexts."

But then I am trying to build a report in WebI and pulling the objects from both the unvierses there are 2 queries being generated and in the report, I am not able to pull the objects from different contexts into the same table.

If I select an object that is in context-1 the objects that are defined in context-2 are being dissabled and vise-versa.

[Former Member · Accepted solution]

Have you ticked "Allow selection of mutliple contexts"?

Also, please note that dimensions from C will have no relevance to measures from A or B and dimensions from B will have no relevance to measures from A. As such, you won't be able to put them in the same block without using calculation contexts. Have a read through the help documentation on In, ForEach and ForAll to help you with that.

Regards,

Mark

[former_member142702]

You can set this behaviour in the universe parameters under SQL->Multiple paths->Allow seleciton of mutliple contexts .

Still since you are solving a fan trap you should keep this option clear.

A solution is to fetch the data from 2 different contents using 2 different webi queries and then use the Merge dimensions functionality in the report itself to join the results.

Regards,

STratos