SAP CAR Interview Cheatsheet (Quick Revision Guide)

SAP Customer Activity Repository (CAR) is SAP’s real-time retail platform used for transaction processing, analytics, forecasting, inventory visibility, and omnichannel execution.

1. What is SAP CAR?

SAP CAR is a centralized, real-time data platform for retail and consumer businesses, sitting between SAP ERP/S/4 & POS systems.

Key Purposes

  • Real-time sales transactions processing
  • Omnichannel inventory visibility
  • Demand forecasting
  • Merchandise analytics
  • Unified customer & product activity database
  • Integration with POS, e-commerce, mobile, ERP, BW, SAP Retail

2. SAP CAR Architecture

  • Built on SAP HANA
  • Fiori UX
  • Consists of multiple CAR components (POSDTA, OAA, UDF, DDF, AMR, etc.)
  • Integration via SLT, IDocs, SAP PI/PO/CPI

3. Major Components of SAP CAR

✅ 1. POSDTA – POS Data Transfer & Audit

  • Inbound POS data (TLOG/TLOGIM)
  • Cleansing, validation, enrichment
  • Error handling & audit trail
  • Interfaces with POS systems, ERP, e-commerce

✅ 2. OAA – Omni-Channel Article Availability & Sourcing

Used for:

  • Real-time ATP
  • Web & store inventory visibility
  • Order sourcing & distribution
  • BOPIS, Ship-from-Store, Endless Aisle

✅ 3. UDF – Unified Demand Forecast

  • Short-term & long-term forecasting
  • Store/product-level forecast
  • ML-based algorithms
  • Promotion uplift forecasting

✅ 4. DDF – Demand Data Foundation

  • Harmonized customer transactions
  • Base for analytics & forecasting
  • Single source of truth for retail activity

✅ 5. AMR – Assortment & Merchandise Recommendations

  • Personalized recommendations
  • ML-driven product affinity
  • Customer basket analysis

Additional Components:

  • Inventory Visibility (IV)
  • Order Repository
  • SAP CAR OPP (Omnichannel Promotion Pricing)

4. Key Processes in SAP CAR

1. POS Data Processing

Flow: POS → POS Inbound → Validation → TLOG → ERP/BI → Inventory update

2. Real-time ATP in CAR (OAA)

  • Checks store + DC stock
  • Checks future receipts
  • Provides sourcing based on:
    • availability
    • transportation cost
    • proximity
    • fulfillment priority

3. Demand Forecasting (UDF)

  • ML algorithms
  • Handles seasonality, trends, events & promotion effects

4. Omnichannel Execution

Supports:

  • BOPIS
  • Curbside pickup
  • Ship from store
  • Click & Collect
  • Reserve Online

5. Important SAP CAR Tables

POSDTA Tables

  • /POSDW/TLOGUS – Raw transactions
  • /POSDW/TLOGF – Final transactions
  • /POSDW/TLOGC – Error & corrections
  • /POSDW/RETAILLOG – Detailed log entries

Inventory Visibility

  • /MRSS/I_TABLES (varies per release)

OAA

  • /OAA/ tables for ATP & sourcing*

DDF/UDF

  • /DMF/ tables* for forecasting and cleansed datasets

6. Integration Points

SAP CAR integrates with:

  • SAP S/4HANA Retail
  • SAP ECC Retail
  • POS Systems (SAP & non-SAP)
  • SAP BW/4HANA
  • SAP Commerce Cloud (Hybris)
  • Middleware: SAP PI/PO, CPI
  • SLT real-time replication

Outbound Integration

  • Sales audit to ERP
  • Inventory adjustments
  • Forecast output to planning systems

7. Performance Considerations

  • HANA pushdown
  • Partition large tables
  • Avoid heavy joins in POS processing
  • Schedule POS inbound during off-peak
  • Use delta loads for faster processing

8. Key Technical Tools

  • SAP Fiori apps for CAR
  • SAP HANA Studio
  • POSDTA Monitor
  • CAR Administration UI
  • DP Engine (for forecasting)
  • Idoc/SLT monitors

9. Mandatory Interview Questions

  1. What is SAP CAR and why is it used?
  2. Explain POSDTA in CAR.
  3. What is OAA and how does ATP sourcing work?
  4. What is UDF vs DDF?
  5. How does CAR support omnichannel retail processes?
  6. Explain the role of TLOG.
  7. What is the difference between SAP CAR and SAP BW?
  8. How does CAR integrate with POS systems?
  9. Explain Click & Collect flow using CAR OAA.
  10. What is Promotion Pricing (OPP) in CAR?
  11. What is CAR’s role in real-time inventory visibility?
  12. How forecasting works in UDF?
  13. What is discrepancy handling in POSDTA?
  14. How do you monitor TLOG data?
  15. Explain SAP CAR architecture components.

10. Real-Time Scenarios

Scenario 1: POS data not reaching ERP

  • Validate POSDTA inbound stage
  • Check mapping rules
  • Look for TLOGC error logs

Scenario 2: Wrong stock shown on e-commerce

  • Check OAA ATP cache
  • Check Inventory Visibility service
  • Validate replication from ERP

Scenario 3: Forecast values look incorrect

  • Check UDF configuration
  • Seasonality factors
  • Promotion uplift model

Scenario 4: BOPIS order sourcing failure

  • ATP result missing → Inventory mismatch
  • OAA rules conflict → Sourcing blocked

Scenario 5: Missing transactions in BI

  • TLOGF not consumed
  • Extraction from CAR to BW failed

11. SAP CAR in S/4HANA Retail

Enhancements

  • Real-time inventory visibility
  • Better Fiori apps
  • Integration with SAP Commerce Cloud
  • Embedded ML-driven forecasting
  • Unified Omnichannel Promotions (OPP)

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