All the SAP Users who are using know that this shift from ECC to S/4HANA is not just a version upgrade, it is a fundamental architectural transformation. It is very important not to see this as a technical update because there are various risks involved like performance issues, broken integrations, data inconsistencies, and compliance risks post-go-live.
In this blog we will break down the core technical differences between SAP ECC and SAP S/4 HANA, with a focus on the integration architecture, complexity in migration, and system behaviour, along with this we will also explain how SEPFUST enables a risk-free, integration-ready migration.
1. SAP ECC vs SAP S/4HANA: Core Architecture Shift
SAP ECC (Legacy Architecture)
- Database-agnostic (Oracle, DB2, SQL Server) - SAP ECC supports multiple databases like Oracle, IBM DB2, and Microsoft SQL Server. This flexible solution allowed enterprises to choose preferred database platforms but it also imposed technical limitations, because they now have to rely on only single solutions for any challenges occurring in their system that too depend upon the service provider.
- Disk-based storage - In SAP ECC, data is primarily stored on disk-based relational databases. Disk I/O operations are significantly slower compared to in-memory processing. To mitigate this limitation, SAP introduced complex buffering strategies and pre-calculated data structures.
- Heavy reliance on:
- Aggregate tables - To improve reporting performance, SAP ECC uses aggregate tables that store pre-summarized transactional data.
For example, instead of calculating totals dynamically, ECC reads values from aggregate tables that are periodically updated.
- Index tables - SAP ECC relies heavily on secondary index tables to speed up database searches. Since databases could not efficiently scan large datasets on disk, indexes were created to optimize frequent query paths.
- Redundant data structures - Because of aggregates and indexes, SAP ECC landscapes often contain multiple tables storing the same business data in different formats.
For example, financial data could exist across several tables for line items, totals, and reporting views.
- Application logic executed mostly at the ABAP layer - In SAP ECC, most business logic is executed in the ABAP application layer, not in the database.
- Custom programs often use:
- Nested SELECT statements
- Loop-based data processing
- Multiple database round trips
This design was necessary due to database neutrality but caused performance bottlenecks as data volumes grew. Complex calculations that could have been executed in the database
were instead processed row-by-row in ABAP.
- Batch-driven reporting - Real-time analytics in SAP ECC is limited. To compensate, ECC relies on:
- Background jobs
- Periodic batch processing
- Pre-calculated totals
Reports are often based on data that is hours or days old, especially in finance and logistics.
This batch-driven approach affects:
- Decision-making speed
- Operational visibility
- Integration with real-time external systems
SAP S/4HANA (Next-Gen Architecture)
SAP S/4HANA was built from the ground up to address the structural limitations of SAP ECC. At its core, S/4HANA is designed to deliver real-time processing, simplified data models, and integration-ready architecture, enabled entirely by the SAP HANA in-memory database.
- HANA-only in-memory database - Unlike SAP ECC, which supports multiple database platforms, SAP S/4HANA runs exclusively on SAP HANA. This database dependency is intentional and foundational to S/4HANA’s capabilities.
SAP HANA stores data directly in memory (RAM) rather than reading it from disk. This eliminates I/O bottlenecks
- Columnar storage with real-time processing - SAP HANA uses columnar storage instead of traditional row-based storage.
- In columnar storage:
- Data is stored column-by-column rather than row-by-row
- Only required columns are read during queries
- Compression ratios are significantly higher
- Elimination of Aggregates - In SAP S/4HANA, traditional aggregate tables are no longer required.
Because HANA can calculate totals and summaries on-the-fly at high speed, SAP removed many pre-calculated data structures that were mandatory in ECC.
- Elimination of Redundant indices - S/4HANA significantly reduces or completely eliminates secondary index tables.
HANA’s in-memory columnar engine performs fast searches without relying on traditional indexing strategies.
- Push-down of logic to database layer - One of the most critical architectural changes in S/4HANA is the push-down of application logic to the database layer.
- Virtual data models via CDS Views - SAP S/4HANA introduces Core Data Services (CDS Views) as the foundation for its Virtual Data Model (VDM).
Impact:
Custom code, reports, and integrations designed for ECC cannot be directly reused without remediation.
