CDS (Core Data Services)CDS
What it is
SAP's data-modelling language for defining semantically rich views, associations and annotations on top of the database — evaluated by HANA close to the data. ABAP CDS is the in-stack flavour used for S/4HANA data models and RAP.
Why it matters for Clean Core
CDS is where modern SAP data logic lives (code pushdown to HANA) and the layer RAP and Fiori build on. Released CDS views are the supported, upgrade-stable way to read SAP business data.
Common pitfall
Treating CDS as 'just a fancy view' and pulling everything into ABAP to process. The point is to push set logic down into CDS (and HANA) and keep ABAP for orchestration — the opposite of classic loop-and-SELECT habits.