topic Is it possible to have multiple data models in single QVW application? in QlikView

Is it possible to have multiple data models in single QVW application?

nagarajupinnibo — Wed, 20 May 2015 06:51:39 GMT

Hi ,

Is it possible to have multiple data models in single QVW application? If Yes, What scenarios we will use this.

Is it right thing to create multiple data models in single QVW.

Can you please explain this??

Thanks,

Nagaraju

Re: Is it possible to have multiple data models in single QVW application?

tresB — Wed, 20 May 2015 06:55:37 GMT

Couple of years ago the restriction(that too with Doc CALs only) was there, now you can have multiple data models in a single qvw.

Re: Is it possible to have multiple data models in single QVW application?

nagarajupinnibo — Wed, 20 May 2015 06:58:16 GMT

Hi tresesco,

Is it good practice to create multiple data models in Qlikview. What scenarios we will create these type of models.

Thanks,

Nagaraju

Re: Is it possible to have multiple data models in single QVW application?

danieloberbilli — Wed, 20 May 2015 06:58:17 GMT

As far as I know, there are limitations regarding the use of Document licenses. If your model moves too far away from the classic star schema (regarding a central fact table and dimension tables with significant smaller amount of distinct values) then it might be, that Document licenses do not work...but I never experienced something like that

Re: Is it possible to have multiple data models in single QVW application?

Wed, 20 May 2015 06:59:30 GMT

YES POSSIBLE!

ON SCRIPT EDITOR!

USE SEPARATE TABS FOR EACH DATA MODEL

Re: Is it possible to have multiple data models in single QVW application?

tresB — Wed, 20 May 2015 07:05:44 GMT

In general, it should be avoided, because that could create confusion on front-end behavior (because of un-associated data model) and would be expensive in terms of script maintenance. However, you could face a situation where there would a small set of data that really is not part of main analysis data, in that case you might want to keep that part as a separate model.

Re: Is it possible to have multiple data models in single QVW application?

petter — Wed, 20 May 2015 07:07:32 GMT

It is tecnical possible but seldom advisable since you can achieve the same effect with document chaining withou the disadvantages. Speed and size will be a challenge for a comprehensive multiple (non-associated) business data models.

Having data islands - one or a few minor tables is not uncommon. Mostly for UI covenience. The bulk data model is the business data model and should be one associated whole. If you have a problem getting the associations/links correctly it might be a sign that you either should split your app into two separate apps or spend even more time on your data modelling.

When it comes to the license terms a customer is specifically not allowed to have two or more business data models (larger) side-by-side with the Small Busines Edition of the server.

Re: Is it possible to have multiple data models in single QVW application?

petter — Wed, 20 May 2015 07:09:41 GMT

Tabs will never separate your data model - tabs are purely a UI covenience

Re: Is it possible to have multiple data models in single QVW application?

jonathandienst — Wed, 20 May 2015 07:14:29 GMT

Well is is possible ... but may not be desirable. You will have to design the model carefully to properly handle multiple fact tables with varying granularity and avoid undesirable circular loops and synthetic keys. You may land up with having duplicate copies of the dimension tables, which will be confusing for the users and it is more complex to encode expressions.

One of the great features of QV is its modular nature, and you lose many benefits of that if you try do to much in a single qvw file.

Re: Is it possible to have multiple data models in single QVW application?

datanibbler — Wed, 20 May 2015 07:16:05 GMT

Hi,

excuse me if this is a stupid question - but what exactly is the factor toggling whether to speak of one or of several data_models in a QlikView_app?

I know that several tables, which are usually linked in some way or other, form a data_model, of course. But:

Is every table that is not linked to any other a separate data_model? Then I have up to 6 or so in some apps.

If it may be that at some point, a Document_license stops working, then I guess it is relevant - I never had any issues with that up to now.

Or maybe everything starting from 2 linked tables?

Thanks a lot!

Best regards,

DataNibbler

Re: Is it possible to have multiple data models in single QVW application?

danieloberbilli — Wed, 20 May 2015 07:21:23 GMT

Regarding Document license...I got this from the server manual:

quote start

The Document CAL can only be used with documents that have a single contiguous data model and do not contain any chasm traps between tables. Most common data models used in QlikView documents can be used for Document CALs. For instance, proper star schemas and snowflake schemas typically have the field with the highest cardinality in the fact table and the keys in dimensional tables have a lower cardinality. For snowflake schemas, the cardinality decreases further when moving away from the fact table. Documents containing such models typically fulfill the above demands and are well-suited for Document CALs. Documents with multiple logical islands are normally not allowed. Multiple logical islands are only allowed, if the additional tables are unconnected and contain only few records or a single column.

In addition, the document may not contain any loosely coupled tables.

Finally, the cardinality (that is, the number of distinct values) of the key fields must decrease when moving away from the fact table.

quote end

Re: Is it possible to have multiple data models in single QVW application?

datanibbler — Wed, 20 May 2015 07:27:18 GMT

Hi Daniel,

that sounds a bit complicated 😉 Honestly, I doubt that Qlik have really implemented in their licenses a check for that about the cardinality of the key_fields ... usually, that is the case, but it's not something you really ought to care for, is it?

Well, logical islands are seemingly not a problem - I have those just about everywhere and I guess others have them, too. Multiple ones, too. Maybe if those were connected, they would establish a second data_model which might be a problem.

Does anyone know this for sure? Has anyone ever actually reached a point where a Document_license does not work anymore?

Re: Is it possible to have multiple data models in single QVW application?

danieloberbilli — Wed, 20 May 2015 07:31:59 GMT

I agree...I tested already some pretty 'messy' models and never had a problem

Re: Is it possible to have multiple data models in single QVW application?

Wed, 20 May 2015 07:34:00 GMT

Really useful question, and some great answers, thanks all.