CDS Explained: Building Effective Data Models in SAP S/4HANA

Published by : BELMACHIA Alaaeddine

Publication date : 15 December 2024

In this article :

Grasping the Practical Role of ABAP CDS

Fundamental Components Shaping CDS Views

Structuring Layers to Maximize Reuse

Annotations That Control CDS Behavior

Working Effectively with Associations and Paths

Optimizing CDS for Performance on HANA

Connecting CDS to SAP Fiori and Embedded Analytics

Patterns Observed in Consulting Implementations

ABAP Core Data Services, known as ABAP CDS or simply CDS in the ABAP context, provides the essential foundation for data modeling in SAP S/4HANA systems and related environments. It enables the creation of semantically rich views directly at the database level, executing joins, calculations, aggregations, and business logic on SAP HANA instead of in the ABAP application layer. In everyday consulting work, CDS views often take the place of older Data Dictionary views and custom ABAP data retrieval code, which speeds up the development of reports, SAP Fiori applications, and analytical content while improving maintainability. When clients require real-time overviews or streamlined OData services for user interfaces, CDS becomes the starting point because it centralizes complex data handling in one reusable definition. This follows the code-pushdown approach, minimizing data movement between the database and application server, particularly evident when working with high-volume data such as sales documents or inventory transactions.Consultants entering SAP S/4HANA projects typically meet CDS first during extensions to standard applications or when building custom analytical queries. Rather than processing data through loops in ABAP programs, a CDS view serves as the direct data provider, allowing HANA to perform intensive operations efficiently. In a sales analysis scenario, for instance, the view aggregates revenue figures by region and time period, includes currency conversions, and executes everything on the database side. This fundamental change redirects performance efforts from ABAP-specific tuning to thoughtful CDS structure design.

Grasping the Practical Role of ABAP CDS

ABAP CDS builds on the broader Core Data Services concept but tailors it specifically to the ABAP platform, with primary optimization for SAP HANA while maintaining a degree of portability. It uses a SQL-based syntax extended by annotations that embed metadata for user interfaces, analytics processing, and OData service definitions. Compared to traditional database views, CDS incorporates business context through associations and annotations, resulting in models that describe themselves clearly. During project handovers, this reduces the need for detailed explanations, as Fiori developers or analytics specialists can interpret the annotations directly to understand field purposes and relationships.Development occurs through Data Definition Language sources in ABAP Development Tools within Eclipse. Upon activation, the system creates runtime artifacts that SAP HANA utilizes for query processing. Standard implementations organize views in layers: basic interface views close to source tables, composite views incorporating joins and logic, and consumption views customized for end-use cases. This structure supports reuse effectively—a single basic view on the material master table, for example, feeds various composite views handling inventory checks, purchasing needs, and cost calculations.Recent releases include projected views that allow targeted adaptations for specific services without altering underlying models. This capability aligns well with clean-core strategies, as it enables extensions while preserving delivered SAP content. In migration projects from SAP ECC to S/4HANA, teams frequently redirect legacy custom reports toward standard or extended CDS views, which substantially reduces overall conversion work.

Diagram of ABAP CDS entity associations and components

Fundamental Components Shaping CDS Views

CDS views begin with entity definitions that select and project fields from database tables or other views. Even basic views typically include explicit key definitions alongside descriptive fields and initial annotations for labels and semantic meaning. Defining keys properly ensures reliable identification, which proves essential for establishing associations and enabling accurate consumption in applications.Associations establish logical links between entities without enforcing physical joins during definition. They rely on path expressions for navigation, such as retrieving customer information from a sales order view through an association labeled _Customer. In delivery tracking implementations, this technique constructed monitoring views that traversed from delivery headers through items to related sales orders seamlessly, with HANA handling path resolution efficiently at runtime.Annotations supply metadata that various frameworks process. User interface annotations such as @UI.lineItem determine columns displayed in SAP Fiori list reports, whereas analytics annotations like @Analytics.dataCategory create OLAP-capable structures. During financial implementations, annotations for currency codes and amount semantics automated conversions in queries, eliminating the requirement for manual ABAP adjustments.Parameters introduce flexibility by allowing dynamic input at execution time. Views parameterized by date ranges or organizational units support reuse across multiple reports through different value assignments. Expressions and built-in functions enable database-level computations, including conditional logic for categorizing overdue items, string manipulations for standardized formatting, and arithmetic for deriving discounted values. In procurement monitoring, date-based functions calculated delivery variances inline, supplying key performance indicators directly without additional ABAP processing.

Illustration of a possible lifecycle of a CDS view:

Structuring Layers to Maximize Reuse

SAP recommends a Virtual Data Model approach that organizes CDS views into distinct layers to combine broad reusability with targeted specialization. Basic interface views operate nearest to the physical tables, delivering clean field projections, associations, and limited logic while carrying the @VDM.viewType: #BASIC annotation. These views function as dependable foundations for subsequent layers.Composite interface views integrate multiple basic views, incorporating business rules, aggregations, and extended associations. Identified by #COMPOSITE, they consolidate information for wider application scenarios. In production environments, such views combined material master data with bill-of-material structures and routing information to enable comprehensive planning analysis.Consumption views focus on particular use cases, frequently incorporating user interface annotations for SAP Fiori elements or @Analytics.query: true for analytical access. They refine the field set, introduce calculated measures, and conceal underlying complexities. For sales oversight applications, consumption views presented essential indicators such as outstanding orders and achievement rates while drawing on shared lower-layer definitions.Layering eliminates unnecessary duplication—across enterprise implementations, individual basic views on customer data supported numerous consumption views spanning sales, credit management, and customer service functions. Modifications at foundational levels flow through consistently, which minimizes regression testing requirements.

Flowchart of associations and path expressions in ABAP CDS

Annotations That Control CDS Behavior

Annotations determine the runtime interpretation of CDS views across different consumption scenarios. User interface annotations such as @UI.selectionField designate fields available for filtering in SAP Fiori applications, while @UI.identification organizes fields within detail displays. These annotations, applied primarily in consumption views, facilitate automatic generation of interface elements based on metadata.Analytics annotations support integrated reporting capabilities. Setting @Analytics.dataCategory: #CUBE transforms a view into a multidimensional cube structure complete with defined measures and dimensions. In overhead cost analysis, annotating actual costs and planned values as measures permitted slicing by time periods or cost center owners within analytical queries.OData-related annotations like @OData.publish: true enable direct service exposure. This approach streamlines integration scenarios by providing ready OData endpoints. In material availability checks, publishing a stock overview view delivered immediate data access for connected warehouse applications.ObjectModel annotations guide aspects of the ABAP RESTful Application Programming Model, such as @ObjectModel.semanticKey for establishing business identifiers. Extensibility annotations facilitate controlled modifications while protecting core definitions. Regular consultation of current annotation references remains necessary, as updates in releases introduce enhanced support for specialized processing.

Working Effectively with Associations and Paths

Associations extend traditional foreign key relationships by accommodating cardinality specifications, join conditions, and optional parameters. One-to-many links from document headers to details rely on precise on-conditions for correct matching. Path expressions within select lists enable direct navigation, such as filtering high-quantity items through SalesOrder._Item[Quantity > 100].Material.In analytical sales processing, this method extracted relevant subsets efficiently without separate subqueries. Parameterized target associations add further dynamism, proving valuable for hierarchical structures like organizational units. Exposed associations benefit from descriptive @EndUserText.label annotations that improve readability in development tools. Consistent naming conventions and clear documentation enhance the usability of views for team members building on them.Enhancing Flexibility Through Parameters and VariablesParameters equip views with runtime configurability. Defining a view with a fiscal year parameter restricts results accordingly, allowing varied executions from ABAP programs or analytical tools by supplying appropriate values. Session variables such as $session.system_language manage context-dependent elements automatically. In global operations, this ensures language-specific texts appear correctly without supplementary logic.Parameters frequently support threshold-based calculations, such as classifying deviations exceeding a specified limit. This mechanism maintains view generality while accommodating diverse reporting requirements across organizational units.

Optimizing CDS for Performance on HANA

Effective CDS modeling capitalizes on SAP HANA capabilities by executing intensive operations at the database layer. Aggregations and filters should reside as low as possible in the view stack to minimize processed data volumes. Intermediate views benefit from excluding non-essential fields, which reduces memory consumption during execution.Join selections matter—inner joins suit mandatory relationships, while left outer joins handle optional ones appropriately. For high-volume financial tables, key-based access patterns enhance retrieval speed. Annotations including @ObjectModel.usageType.sizeCategory assist the query optimizer in selecting efficient plans. In demanding reporting scenarios, execution plan analysis through database tools identifies optimization opportunities early. Buffering remains applicable for static, low-volume views, although HANA characteristics diminish its overall impact.

Flow diagram of ABAP CDS integration with Fiori and analytics

Connecting CDS to SAP Fiori and Embedded Analytics

CDS serves as the primary data source for SAP Fiori applications via OData service exposure. Consumption views equipped with user interface annotations produce list reports, object pages, and overview pages automatically. In equipment maintenance scenarios, annotated notification views enabled rapid filtering and graphical representations within applications.Embedded analytics leverages CDS cubes to deliver multidimensional exploration directly in the SAP Fiori Launchpad. Users perform drill-downs and slicing operations seamlessly within the transactional system. Standard Virtual Data Model views delivered by SAP cover extensive business domains, with custom extensions addressing organization-specific requirements.Applying CDS Within the ABAP RESTful Application Programming ModelThe ABAP RESTful Application Programming Model relies on CDS as its foundational data layer for building transactional applications. Interface views establish the core structure, behavior definitions introduce actions and validations, and service definitions control exposure.Development typically begins with root entities and projections, followed by behavior specifications that support draft handling and persistence management. This combination generates OData V4-compliant services with limited additional coding. In cloud-oriented projects, RAP combined with CDS semantics delivers managed, upgrade-stable developments suitable for modern extensions.

Integrated diagram of CDS in RESTful Application Programming

Patterns Observed in Consulting Implementations

Financial implementations frequently employ CDS views to consolidate general ledger data, incorporating currency handling and fiscal period logic for reporting purposes. Views joining universal journal entries with supplementary details, annotated appropriately, support analytical consumption effectively.Supply chain scenarios construct inventory overviews that integrate stock levels, reservations, and procurement documents through associations enabling end-to-end traceability. Resulting consumption views deliver accurate available-to-promise computations in real time.Sales processes benefit from fulfillment views that navigate from order headers and items to subsequent deliveries and invoices, deriving performance metrics such as delivery timeliness. During system upgrades, shifting legacy ABAP-based reporting to CDS-driven analytical queries often yields substantial performance gains.CDS development maintains steady advancement, incorporating refinements that address increasingly sophisticated requirements while reinforcing clean-core adherence.