topic Re: Which Approach is better in QlikView

Which Approach is better

sarfaraz_sheikh — Tue, 26 Dec 2017 15:18:39 GMT

Hello Folks,

I have created the data model in three different ways, Can anyone tell me which one is better approach to follow.

1) Approach

2> Approach :

I wanted to know which one is better from all respect like performance, reload and etc.

Guidence would be much appreciated.

Thanks

Sarfaraz

Re: Which Approach is better

sunny_talwar — Tue, 26 Dec 2017 15:32:37 GMT

I am seeing only two approaches, is there a third one you wanted to show?

With regards to the performance, I don't see too much difference between the two... it's just a matter of preference as to how you would want you data model to look like? A single fact table or two fact table model?

Re: Which Approach is better

pipuindia99 — Tue, 26 Dec 2017 16:13:12 GMT

Hi,

Where is the 3rd Data model?

Re: Which Approach is better

sarfaraz_sheikh — Tue, 26 Dec 2017 16:15:30 GMT

Third approach is the join between two fact tables .

Sarfaraz

Re: Which Approach is better

Anil_Babu_Samineni — Wed, 27 Dec 2017 02:29:03 GMT

I would go first one

Re: Which Approach is better

pradosh_thakur — Wed, 27 Dec 2017 02:54:53 GMT

if you have an one to one mapping you should always go for apply map.

https://community.qlik.com/blogs/qlikviewdesignblog/2012/09/18/one-favorite-function-applymap

https://community.qlik.com/blogs/qlikviewdesignblog/2012/09/12/to-join-or-not-to-join

regards

Pradosh

Re: Which Approach is better

Anonymous — Wed, 27 Dec 2017 04:08:58 GMT

I prefer approach one

Re: Which Approach is better

sunny_talwar — Wed, 27 Dec 2017 12:28:26 GMT

Between approach 1 and 2, you prefer 1? What is the basis for this preference? I understand the preference of 1 between ApplyMap and a join... but not sure I understand how you can choose between 1 and 2?

Re: Which Approach is better

pradosh_thakur — Wed, 27 Dec 2017 13:09:41 GMT

I didn't mention i prefer 1st sunny. I provided the link for the OP to go through when apply map and when join . I guess you commented on the wrong comment.

Re: Which Approach is better

sunny_talwar — Wed, 27 Dec 2017 13:11:35 GMT

You did mention that if it is a one to one mapping then you would go with ApplyMap. That means that you are indirectly suggesting to pick one. I wonder why. My comment was not to portray that you are wrong, I just want to know if I am missing anything

Re: Which Approach is better

pradosh_thakur — Wed, 27 Dec 2017 13:27:24 GMT

Haha. You never miss anything sunny!!

he was using apply map in both the approach so in edition to your answer i posted those link.

one quick query here. If we have lets say few million of records and we do it according to first approach than we will have one fact table to associate with other tables. will it not take less time when compared to having two tables which are associated on run time with each other as well as other tables.

I read in the community that

1: Qlikview association is comparable to Outer join but at run time and not during script execution.

2: when we compare two tables joined into one table and those two tables not joined and in form of two tables (like join and keep) than the slicing and filtering of joined table will be faster.

please correct me sunny if i understood anything wrong here.

regards

Pradosh

Re: Which Approach is better

sunny_talwar — Wed, 27 Dec 2017 13:49:38 GMT

Yes, we have seen advantages (slightly faster running expressions) of combining a table into a single fact table with massive amount of data. But I am not sure how advisable it is to actually do this all the time.... the reason i say this is because why not just have a single table model all the time? Because things are not always simple, and at times it is easier to maintain and understand a multiple table model. So, I think it comes down to preference of what your data model requirement need is.

But coming back to the question, between the first two options, I don't see any difference in reload times. On the front end, we might see some differences with massive amount of data, but would be negligible for few million rows.

Re: Which Approach is better

sunny_talwar — Wed, 27 Dec 2017 13:54:05 GMT

Let me just clarify that the above is based on what we have seen in the past. I have not done any testing and is my opinion. I suggest performing some sort of tests before making final decisions.

Re: Which Approach is better

pradosh_thakur — Wed, 27 Dec 2017 13:54:51 GMT

thank you sunny.

Re: Which Approach is better

qliksus — Thu, 28 Dec 2017 04:43:03 GMT

Approch 2 doesn't have any subfield so that might reduce the load time a bit and with just 2 fact tables and you letting Qlikview create its own join instead of a explicit one using the join keyword i feel approach 2 would be better