Guide recrutement data
Test technique Snowflake : ce qu'on evalue en entretien
Snowflake a revolutionne le data warehousing. Sans maitrise du modele economique, les couts peuvent exploser.
Data Builder·Juin 2025·7 min de lecture·Data Engineer · Analytics Engineer
Snowflake a revolutionne le data warehousing avec la separation stockage/calcul. Mais sans maitrise du modele economique, les couts peuvent exploser.
1Architecture stockage/calcul
Question discriminante
Expliquez l'architecture Snowflake. Pourquoi la separation stockage/calcul est-elle un avantage ?
- Virtual Warehouses — suspendus quand inactifs, cout nul
- Multi-cluster warehouses — scale horizontal pour la concurrence
- Auto-suspend et resume — optimisation des couts
2SQL Snowflake : specificites
- QUALIFY — filtrer sur window functions
- VARIANT et FLATTEN — stocker et aplatir du JSON
- Zero-copy cloning — dupliquer instantanement sans copier les donnees
- DATA SHARING — partager en lecture seule avec d'autres comptes
3Time Travel et Fail-safe
Question discriminante
Qu'est-ce que le Time Travel ? Dans quel scenario l'avez-vous utilise ?
- AT/BEFORE — requeter a un timestamp ou avant un statement
- UNDROP — restaurer une table supprimee
- Fail-safe — 7 jours supplementaires, support uniquement
4Streams et Tasks
Question discriminante Senior
A quoi servent les Streams et Tasks ? Cas d'usage concret.
Les Streams capturent les changements (CDC). Les Tasks executent du SQL sur un schedule. Ensemble, ils permettent des pipelines incrementaux dans Snowflake.
- Dynamic Tables — materialized views incrementales (2024)
5Performance et couts
Question discriminante
Comment optimisez-vous les couts Snowflake en production ?
- Auto-suspend timeout adapte — ne pas laisser tourner inutilement
- Warehouse sizing — XS a 6XL selon le besoin
- Resource monitors — alertes et limites de credits
6Grille par niveau
| Niveau | Maitrise attendue | Signal GO | NO-GO |
|---|
| Junior | SQL Snowflake, connexion, tables de base | Comprend les virtual warehouses | Ne sait pas ce qu'est un virtual warehouse |
| Confirme | Time Travel, cloning, VARIANT, sizing | A utilise Time Travel en prod, gere auto-suspend | Ne connait pas Time Travel |
| Senior | Streams, Tasks, clustering keys, resource monitors | A construit un pipeline CDC avec Streams | N'a jamais configure de resource monitor |
| Lead | Architecture, Data Sharing, gouvernance | A mis en place du Data Sharing inter-comptes | Ne connait pas les Dynamic Tables |
Data hiring guide
Snowflake technical interview: what we really assess
Snowflake revolutionized data warehousing. Without mastering the economic model, costs can explode.
Data Builder·June 2025·7 min read·Data Engineer · Analytics Engineer
Snowflake revolutionized data warehousing with storage/compute separation. But without mastering the economic model, costs can explode.
1Storage/compute architecture
Key question
Explain the Snowflake architecture. Why is storage/compute separation an advantage?
- Virtual Warehouses — suspended when idle, zero cost
- Multi-cluster warehouses — horizontal scaling for concurrency
- Auto-suspend and resume — cost optimization
2Snowflake SQL: specific features
- QUALIFY — filter on window functions
- VARIANT and FLATTEN — store and flatten JSON
- Zero-copy cloning — instantly duplicate without copying data
- DATA SHARING — share read-only access with other accounts
3Time Travel and Fail-safe
Key question
What is Time Travel? In what scenario have you used it?
- AT/BEFORE — query at a timestamp or before a statement
- UNDROP — restore a dropped table
- Fail-safe — 7 additional days, support access only
4Streams and Tasks
Senior key question
What are Streams and Tasks used for? Give a concrete use case.
Streams capture changes (CDC). Tasks execute SQL on a schedule. Together, they enable incremental pipelines within Snowflake.
- Dynamic Tables — incremental materialized views (2024)
5Performance and costs
Key question
How do you optimize Snowflake costs in production?
- Adapted auto-suspend timeout — avoid leaving warehouses running unnecessarily
- Warehouse sizing — XS to 6XL based on need
- Resource monitors — credit alerts and limits
6Scoring grid by level
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