Module 16: BW/4HANA & HANA Pushdown (BW/4HANA 2.0)
HANA pushdown is the single most important paradigm shift in BW/4HANA.
If you do not understand pushdown correctly, BW/4HANA becomes an expensive classic BW.
This module covers:
- Code pushdown principles
- Pushdown vs ABAP logic
- ELT vs ETL
- Performance comparison
- When NOT to push down
1. What is HANA Pushdown?
Definition
HANA pushdown means:
Executing data-intensive logic as close to the database as possible, instead of on the ABAP application server.
❌ Pull data to ABAP → process → push back
✅ Push logic to HANA → process in DB
Why Pushdown Exists
SAP HANA is:
- In-memory
- Massively parallel processing
- Columnar storage
- Optimized SQL execution
Move logic to data, not data to logic.
2. Code Pushdown Principles (Core Philosophy)
Principle 1: Data Volume Reduction Early
- Filter early
- Aggregate early
- Project only required fields
The less data you move, the faster everything becomes.
Principle 2: Parallelism over Loops
- SQL set-based processing
- Avoid row-by-row loops
❌ LOOP AT itab
✅ SELECT … GROUP BY
Declarative logic allows the database optimizer to work.
Principle 3: Declarative over Imperative Logic
- SQLScript
- CDS views
- AMDP
3. Pushdown vs ABAP Logic (Very Important)
Where Logic Runs
| Logic Type | ABAP Logic | Pushdown Logic |
|---|---|---|
| Execution | App Server | HANA DB |
| Processing | Row-based | Set-based |
| Parallelism | Limited | Massive |
| Performance | Moderate | Very High |
| Scalability | Lower | Higher |
Examples in BW/4HANA
| Scenario | Old Approach | BW/4HANA Approach |
|---|---|---|
| Lookups | ABAP routines | AMDP |
| Aggregation | End routine | HANA SQL |
| Joins | ABAP logic | CompositeProvider |
| Calculations | Query CKFs | Model / AMDP |
If logic runs in ABAP, you are not using BW/4HANA correctly.
4. ELT vs ETL (Fundamental Shift)
4.1 ETL (Classic BW)
Extract → Transform → Load
Characteristics:
- Transformations in ABAP
- Heavy staging
- Multiple persistence layers
4.2 ELT (BW/4HANA)
Extract → Load → Transform
Characteristics:
- Raw data loaded quickly
- Transformations executed in HANA
- Fewer layers
Why ELT is Better in BW/4HANA
| Aspect | ETL | ELT |
|---|---|---|
| Load speed | Slower | Faster |
| Complexity | High | Lower |
| Pushdown | Limited | Strong |
| Scalability | Moderate | Excellent |
BW/4HANA is ELT-first, not ETL-first.
5. Performance Comparison (Realistic View)
Example Scenario
Sales fact table with 100 million records
| Approach | Runtime |
|---|---|
| ABAP routines | Minutes |
| AMDP pushdown | Seconds |
| HANA SQL | Sub-seconds |
ABAP loops do not scale on large datasets.
6. Pushdown Techniques in BW/4HANA
Where Pushdown Happens
| Area | Pushdown Mechanism |
|---|---|
| Transformations | AMDP |
| Modeling | CompositeProvider |
| Reporting | HANA execution plans |
| Semantics | CDS / SQL |
Key BW Objects Supporting Pushdown
- aDSO (HANA tables)
- CompositeProviders
- Open ODS Views
- AMDP transformations
7. When NOT to Push Down (Very Important)
Pushdown is powerful — but not universal.
Valid Reasons NOT to Push Down
Very complex ABAP-only logic
External API calls
Text processing not suited for SQL
Very small data volumes
Wrong Reasons (Anti-Patterns)
"ABAP is easier"
"We always did it this way"
"SQLScript is scary"
8. Pushdown Design Best Practices
Push logic down by default
Measure performance before & after
Use AMDP for complex logic
Simplify queries
Don't mix ABAP + SQL unnecessarily
Don't over-persist data
Don't build logic-heavy queries
9. BW/4HANA 2.0 vs BW 7.5 (Pushdown)
| Area | BW 7.5 | BW/4HANA |
|---|---|---|
| Pushdown | Optional | Mandatory |
| ABAP routines | Common | Discouraged |
| Performance tuning | Aggregates | Modeling |
| Scaling | Vertical | Horizontal |
10. Interview-Grade Questions
Q1. What is HANA pushdown?
Answer: HANA pushdown is the strategy of executing data-intensive logic directly in the HANA database to leverage in-memory processing and parallel execution.
Q2. When should pushdown be avoided?
Answer: When logic cannot be expressed in SQL, requires ABAP-only capabilities, or involves very small datasets where pushdown provides no benefit.
11. Summary
- Pushdown is core to BW/4HANA
- ELT replaces ETL
- ABAP logic is minimized
- Performance gains are massive
- Pushdown must be applied wisely
12. What's Next?
➡️ Module 17: Advanced Performance Optimization
BW/4HANA performance issues are usually design mistakes, not hardware problems.