topic Re: Galaxy model (two fact tables, multiple dimensions) in QlikView

Galaxy model (two fact tables, multiple dimensions)

Zaga_69 — Sat, 16 Nov 2024 19:12:49 GMT

Hi all,

I am trying to understand why this model does not work. I have two fact tables plus multiple dimensions (see image below).

Why i have this circular references when having unique keys?

Of course I could avoid that by concatenating these tables, but I need to understand why in Qlik having tow fact tables linked to the same dimension cause troubles.

Thank you in advance,

Re: Galaxy model (two fact tables, multiple dimensions)

Claudiu_Anghelescu — Fri, 31 Jan 2020 13:30:07 GMT

Try to rename some keys in Fact tables in order to eliminate the Loop.

Re: Galaxy model (two fact tables, multiple dimensions)

marcus_sommer — Fri, 31 Jan 2020 16:49:25 GMT

I think this is the best explanation why it couldn't work: Circular-References

- Marcus

Re: Galaxy model (two fact tables, multiple dimensions)

BeeHive — Fri, 31 Jan 2020 18:00:01 GMT

There is not common fields between the two fact tables 🙂

If you have a closer look, you will see that each field in the fact tables has as a prefix the table name. I did that in order to avoid synthetic keys (qualify() function).

Thanks!

Re: Galaxy model (two fact tables, multiple dimensions)

marcus_sommer — Mon, 03 Feb 2020 08:09:37 GMT

There are sensible usecases for qualifying - but linking fields respectively the reverse of avoiding them belong not them - this task should be always done explicitly.

Personally I would just concatenate the tables and if you need to know which values come from which source then add a source-field.

- Marcus

Re: Galaxy model (two fact tables, multiple dimensions)

Brett_Bleess — Mon, 24 Feb 2020 17:48:24 GMT

The issue is related to the circular reference post Marcus gave you, in your outlying tables you are calling from both fact tables, that is what is causing the reference, so you will have to kill that. Pretty certain things are working as expected given the data model in this case. Be sure to read over the Design Blog link Marcus posted earlier, that should help make sense of things, you have qualified things, but given those other tables are calling from both tables, that is what is creating the circular reference... One of the engineers would have to explain things further, but if you fix that part of things in those other tables, that should stop things.

Regards,
Brett