CDS View vs Atribute view

[Former Member]

Hello All,

I need to know is CDS view and Attribute view are co related and what is the difference between CDS view and Attribute view.

Please suggest.

LR Reddy.

[christianlechne]

Hi Reddy,

an attribute view is one of the view types available in the HANA modelling environment. The attribute view (also known as Join View) is intended to join tables together. One scenario might be to use an attribute view as a single dimension in an analytical view.

YOu find more information on that in chapter 6.2 the SAP HANA Modelling Guide (http://help.sap.com/hana/SAP_HANA_Modeling_Guide_for_SAP_HANA_Studio_en.pdf)

CDS (Core Data Services) is a layer above the "pure" database in order to define semantically-enriched data models. In contrast to the attribute view a CDS document can define tables (called entities), views, table types, associations and annotations. So as you can see CDS is much more powerful than a plain attribute view. You can find an introduction to CDS views in the HANA developer guide chapter 3.1 (http://help.sap.com/hana/SAP_HANA_Developer_Guide_for_SAP_HANA_Web_Workbench_en.pdf)and an extensive description on them in the reference guide (http://help.sap.com/hana/SAP_HANA_Core_Data_Services_CDS_Reference_en.pdf)

There are also so called CDS views that come from the ABAP world. These are ABAP managed artefacts where you can also do data modelling. The capabilities are much bigger than the ones of classical views in ABAP and allow also some semantical annotations (more to come with NW 750 as far as rumors say). Nevertheless currently (NW 740) the DDL files of a CDS view allow only the modelling of one single entity (in contrast to a CDS document in the HANA repository where you can define several artefacts in one CDS file). More information can be found in ABAP Keyword Documentation of CDS. What is also worth to mention: nearly all of the features of a CDS view are available on any DB so no HANA needed to use CDS.

So summarizing attribute views are one simple type of views intended to join tables (and in case apply some filtering). The attribute views are HANA managed, so in order to adress them in ABAP you would need an external view. Transportation is also an issue as the lifecylce of the attribute view is managed by HANA whereas the external view is managed by ABAP (i. e. CTS)

CDS is a complete layer within HANA in order to do sematically-rich data modeling. So both deal with data modeling but there is no close connection between them.

ABAP CDS views allow advanced and also semntically rich data modelling in ABAP and (as a big advantage) are ABAP managed, so you just need classical transport management via CTS.

If you are on ABAP I would therefore go for CDS views instead of attribute views.

Hope that helps (and does not add confusion :-))

BR

Christian

P.S. If you go for modelling I would only use calculation views and avoid attribute and analytical views (although not officially deprecated, you can see where the journey goes when taking a look at HANA Live content). Anyway that depends onyour concrete scenario

[Former Member]

Hi Christian,

Thanks a lot for detailed information..,