Content.
this is a try to answer the question - Filter down to HANA View through filter and not prompt. But the answer was a bit too long to make a direct reply.
Intro.
The initial question is coming from HANA, but relevant also for SAP BW and Universes. Keep in mind that Design Studio main focus was SAP BW and this is the most advanced system in terms of work with prompts (BEx Variables). HANA is having a slightly different concept and also functionality is different.
Basics
Let us start with BW, this is the system where the difference is the biggest.
The difference in short answer...
the difference between filter and prompts is very important in case you work on SAP BW system. Prompts are more powerfull (customer exit, permission check, merging, etc).
In terms of SAP HANA prompts are based on the parameters - once pre-filled, you cannot filter to something which is not included in the filter selection. you need again to change the prompt. but you can filer down in the space of the pre-selection done by prompts.
Prompts vs FIlters
- The prompts
- can be merged or unmerged (valid mainly for BW). in case of merged prompts, all data sources in the same session have always the same values. You cannot merge filters, those are always applied to one data source
- can be mandatory - if not set with default value, user will always see the prompt dialog. You cannot make filters mandatory.
- can be pre-filled via customer exits in BEx Variable processing, this is not the case for filters.
- can pre-select your navigation space before you can start filtering. This is depending on your BEx Query definition. In such case, you cannot even use filtering to change the space - you need to again to change prompts
- can be dependent on each other (like hierarchy and hierarchy node) and you can propose default values based on the dependency in prompt dialog (also via customer exits)
- The filters
- are depending on the data source and do not influence other data sources, changes in prompts are forcing (in merged case) other data sources to reload.
- are probably cheaper to execute in navigation, as the processing does not have too much machinery behind. This is of course scenario based.
As of today, I have not much more, but perhaps I will actualize later on.
How this behaves in HANA?
It is a good question actually when talking about HANA, as there the input parameters are not yet so powerful as in BW. But, also here some of the differences are matching. Especially important is the difference that you can force the input parameters to be pre-filled and by this you can force the user to pre-select some reporting space to reduce the amount of data pushed to the server.
In which aspect are the filters and prompts equal?
Important aspect is independent if filter or prompts, both are influencing the data source and invalidating the result set, therefore after change ALWAYS a call will be made to the source system (HANA, or BW). And here also, in BW there are more consequences on prompts then filters, eg. when you have merged prompts - other data sources will be forced to reload the data. Filter is working only on one data source. Of course in HANA the behavior is different.
Summary.
There is a difference, use it wisely 😉
