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Google·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
Apr 2026

Summary

Google data engineer interview focused on system design, specifically building an ETL pipeline for a machine learning platform on AWS. Pretty technical and open-ended, which I wasn't fully prepared for.

Questions Asked (1)

Q1

Design an ETL pipeline for a machine learning platform running on AWS.

System DesignTechnical Trade-offsData Modeling
Author's notes

This is a big open-ended question and I spent the first few minutes just trying to scope it properly.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements: data sources, volume, velocity, variety, and ML use cases (training vs. inference). Then propose a high-level architecture using AWS services (e.g., Kinesis, Glue, S3, Redshift, SageMaker) and dive into trade-offs around batch vs. streaming, storage formats, and orchestration.

Pro tip: Emphasize data quality and lineage from the start—ML models are only as good as their data. Mention how you'd handle schema evolution and backfills without disrupting training pipelines.

1. Clarify Requirements

Ask about data sources, volume, latency needs, and ML use cases (e.g., real-time inference vs. batch training). This scopes the design and shows you avoid assumptions.

2. Design Data Ingestion

Choose AWS services for ingestion: Kinesis for streaming, AWS Glue or DMS for batch, and S3 as the landing zone. Discuss handling different data formats and frequencies.

3. Plan Data Processing & Storage

Outline transformation steps using Glue/EMR/Lambda, and storage layers (S3 for raw/processed, Redshift/S3 for analytics). Highlight partitioning, columnar formats (Parquet), and cataloging with Glue Catalog.

4. Orchestrate & Automate

Use AWS Step Functions or MWAA (Managed Workflows for Apache Airflow) to schedule and monitor pipelines. Include error handling, retries, and alerting.

5. Integrate with ML Platform

Explain how processed data feeds into SageMaker for training and inference, including feature stores, versioning, and monitoring for data drift.

Key Points to Mention

  • Batch vs. streaming trade-offs: cost, latency, complexity
  • Data lake vs. data warehouse: when to use S3 vs. Redshift
  • Schema evolution and data quality checks (e.g., AWS Deequ)
  • Orchestration and monitoring: Step Functions, CloudWatch, lineage
  • Security: IAM roles, encryption at rest/in transit, VPC endpoints
  • Cost optimization: S3 lifecycle policies, spot instances for EMR, right-sizing

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.