Open ODS Views – virtual to persistent switch
See more in our hbite Open ODS Views
It is a useful property of the Open ODS View that it is designed to cover not only virtual access to data but also allows to transform and transfer data from a given (possibly remote) table with data to a BW adso with data and access it in query.
This is the reason why, in the Open ODS View, we distinguish between the different multidimensional semantics (fact, master data and text) each of which corresponds to separate tables in star schema:
- Facts will be stored separately from master data dimensions;
- Similarly, text tables require a separate storage from master data, since they have an additional key field specifying the language code.
Thus, creating a query via Open ODS ensures that the whole model consists of structures that can –if the need arises –be converted into BW managed stored data.
There is, of course, a variety of reasons for such a switch:
- it might be difficult to keep required Agreements with remote access,
- it may be easier to work with a stable daily snapshot of data, or
- the transformations to combine external data with other BW data could be complex to be executed real time.
It is important in such a switch scenario is that all the modelling objects(e.g. queries, work books) built for the virtual access can be used after the switch as well.
Open ODS ensures that by allowing to exchange the source object under an Open ODS View: after creating the BW adso (or having it generated by the system) you can replace, e.g. the original database table with the newly created BW adso and continue working with your previously built queries.
With BW 7.40 SP05 it is possible to generate an adso based on fields (only available with note 1922533) from an Open ODS View.
It is possible to exchange the original source object of the Open ODS View with the newly generated DSO.
Picture: Data flow of an Open ODS View after switch to persistence
Step by Step Procedure:
Perquisites: You are on updated version of BW4HANA, an OpenODSView on HANA table is already created. Queries also exist on this openODSView.
Goal: You want to store data in an adso in BW for the openODSView dataflow without changing any of the structures in data flow (queries, OpenODSView)
Step 1: Open your OpenODSView, in the general tab, click on ‘Generate dataflow”
This creates a datasource in your source system which you are using (here HANA source system)
Step 2: Create an adso with above datasource as template. Choose standard dso type and specify key fields.
Note: Only Datastore objects for which all reporting takes place on the active table are supported.
Step 3: Create transformation and dtp for your adso with datasource created above as source (datasource is same as data flow here)
Load and activate the request.
Step 4: Go to your OpenODSView again and choose ‘Edit” in general tab
Step 5: Change your source from DB table to DataStore Object (advanced)
Save and activate your OpenODSView
Check the data in the query which was based on this OpenODSView.
Now you have OpenODSView and query with data stored in adso. This was achieved without changing existing query or openODSView.