The impact of a wrong cardinality

[backhandx]

 Hello everyone,

I have a question regarding the cardinality in Framework Manager.

What is the impact of inversing the cardinality between two Query subjects?

For example, if we have 2 query subjects A and B with a cardinality : 1:n - 1:1. What would be the problem if we inverse the cardinality like this 1:1 - 1:n.

Thanks in advance

[Lynn]

Hello everyone,

I have a question regarding the cardinality in Framework Manager.

What is the impact of inversing the cardinality between two Query subjects?

For example, if we have 2 query subjects A and B with a cardinality : 1:n - 1:1. What would be the problem if we inverse the cardinality like this 1:1 - 1:n.

Thanks in advance

There is a section in chapter 9 of the Framework Manager user guide that describes cardinality. You haven't provided much context in your question. Is A your fact table or is B your fact table? Are there other query subjects joining to either of these? Do you already have published packages from this model with the joins as they are now? Why do you feel it needs to be different? Is the SQL that gets generated incorrect in some way?

[backhandx]

I will ask the question differently.
What could be the problem if we don't assign the correct cardinality between two query subjects?
And how to do to know the correct cardinality to set between 2 query subjects?

Thanks

[MFGF]

I will ask the question differently.
What could be the problem if we don't assign the correct cardinality between two query subjects?
And how to do to know the correct cardinality to set between 2 query subjects?

Thanks

Hi,

What could be the problem if we don't assign the correct cardinality between two query subjects?

Best case, if you're lucky, no issue. Worst case, a dimension is treated as a fact or vice versa, and you end up with an incorrectly generated query (either an unwanted stitch query or not getting a stitch query where one is appropriate). Take a look at the documentation Lynn pointed you to - it describes how query subjects are identified as either dimensions or facts based on cardinalities.

And how to do to know the correct cardinality to set between 2 query subjects?

The simple answer is to know the data. If you are linking two tables, what relationship do the rows in one table have to the rows in the other? One to many? Many to one? One to one?

It also seems like you haven't yet got a full understanding of how the query engine generates queries. This understanding has a huge impact on how you build your model in FM, and how you should model your objects to resemble star schemas in order to get accurate, predictable results in your reports. The easiest and most productive way to gain this understanding is to take the FM training - it is one of the best investments you could make.

Good luck!

MF.