Google

Leading technology company specializing in search, cloud, and AI.

4 Rounds ~21 Days Very Hard

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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

All Roles AI Engineer 47 Cloud Engineer 65 Data Analyst 43 Data Engineer 76 Data Scientist 53 Machine Learning Engineer 15 ML Engineer 52 Product Manager 15 Software Engineer 33

All Topics SQL 10 Data Pipeline 5 Data Governance 3 Data Warehousing 3 Algorithms 3 Data Lake 3 BigQuery 3 System Design 3

Data Engineer • Behavioral • medium

Tell me about a time you simplified a complex data platform decision across multiple teams.

#Communication #Stakeholders

Practice

Data Engineer • Behavioral • medium

Describe a situation where a data pipeline you owned went down in production. How did you handle it?

#On-Call #Problem Solving

Practice

Data Engineer • Behavioral • medium

How do you handle disagreements with data analysts or scientists who want features that compromise pipeline reliability?

#Conflict Resolution

Practice

Data Engineer • Behavioral • medium

Tell me about a time you significantly improved the performance of a data system.

#Performance #Optimization

Practice

Data Engineer • Behavioral • hard

Describe how you've balanced technical debt vs. new feature development in a data platform.

#Prioritization

Practice

Data Engineer • Behavioral • medium

Tell me about a time you onboarded a new data source that had significant quality issues.

#Problem Solving

Practice

Data Engineer • Behavioral • easy

Describe your experience mentoring junior data engineers.

#Mentoring #Collaboration

Practice

Data Engineer • Behavioral • easy

How do you stay current with rapidly evolving data engineering tools and practices?

#Growth Mindset

Practice

Data Engineer • Behavioral • medium

Tell me about a time you had to design a data pipeline with highly ambiguous requirements. How did you figure out what to build?

#Ambiguity #Googleyness #Communication

Practice

Data Engineer • Behavioral • medium

Describe a situation where you disagreed with a senior engineer or product manager on a technical design choice. How did you resolve it?

#Conflict Resolution #Collaboration #Googleyness

Practice

Data Engineer • Behavioral • medium

Tell me about a time a data pipeline you owned failed in production. What was the business impact, and what steps did you take to fix it and prevent it from happening again?

#Incident Management #Ownership #Post-mortem

Practice

Data Engineer • Coding • medium

Write a SQL query to find the second highest salary per department.

#Window Functions #SQL

Practice

Data Engineer • Coding • medium

Write a SQL query to compute a 7-day rolling average of daily sales.

#Window Functions #Analytics

Practice

Data Engineer • Coding • hard

Implement a rate limiter in Python for an API using a sliding window approach. The rate limiter should allow a maximum of N requests per minute per user.

#Queues #Sliding Window #Concurrency

Practice

Data Engineer • Coding • medium

Given a list of user session time intervals on YouTube represented as [start_time, end_time], write a Python function to merge all overlapping sessions and return the consolidated active viewing periods.

#Arrays #Sorting #Intervals

Practice

Data Engineer • Coding • hard

Write a SQL query to find the longest streak of consecutive days a user has logged into Google Workspace. The input table has user_id and login_date.

#Window Functions #Gaps and Islands #CTEs

Practice

Data Engineer • Coding • medium

Write a SQL query to calculate the rolling 7-day average of daily video views per category on YouTube, ensuring days with zero views are still accounted for in the average.

#Window Functions #Aggregation #Rolling Averages

Practice

Data Engineer • Coding • medium

Write a Python function to parse a massive (100GB+) log file of Google Search queries and return the top K most frequent IP addresses. You have limited RAM.

#Heaps #Hash Maps #Log Parsing #Big O

Practice

Data Engineer • Coding • medium

Write a SQL query to find the top 3 highest-grossing apps in each region, but only include regions that have at least 100 active apps.

#CTEs #Window Functions #Filtering

Practice

Data Engineer • System Design • hard

Design a data model for an e-commerce platform tracking orders, users, and products.

#ER Modeling #Dimensional Modeling

Practice

Data Engineer • System Design • hard

How would you design a data warehouse for a ride-sharing company from scratch?

#Architecture #Design

Practice

Data Engineer • System Design • hard

Design an ETL pipeline that ingests 10TB of raw clickstream data daily.

#ETL #Batch Processing

Practice

Data Engineer • System Design • hard

How would you design a data pipeline that needs exactly-once delivery guarantees?

#Exactly-Once #Kafka

Practice

Data Engineer • System Design • hard

How would you design a real-time anomaly detection pipeline for 100K events/sec?

#Real-Time #Anomaly Detection

Practice

Data Engineer • System Design • hard

Design a data pipeline for Google Search query logs at 100K QPS.

#Scale #Google

Practice

Data Engineer • System Design • hard

Design a real-time streaming data pipeline to detect click fraud in Google Ads. How would you ingest, process, and store the data to flag fraudulent clicks within seconds?

#Streaming #Pub/Sub #Dataflow #Fraud Detection

Practice

Data Engineer • System Design • hard

Design the data warehouse architecture for Google Play Store analytics. Stakeholders need daily reports on app downloads, revenue, and crash rates by region and device type.

#Data Warehousing #BigQuery #Schema Design #ETL

Practice

Data Engineer • System Design • hard

Design a batch processing pipeline to update Google Maps ETA prediction models based on daily historical traffic data. The data volume is petabytes per day.

#Batch Processing #MapReduce #DAGs #Orchestration

Practice

Data Engineer • Technical • hard

What is Data Vault methodology? How does it differ from Kimball?

#Data Vault #Kimball

Practice

Data Engineer • Technical • medium

Explain the concept of a data lakehouse. What are its advantages over a traditional data warehouse?

#Data Lakehouse #Data Warehouse

Practice

Data Engineer • Technical • hard

How do you handle schema evolution in a data pipeline without breaking downstream consumers?

#Schema Evolution #Backward Compatibility

Practice

Data Engineer • Technical • medium

What is a medallion architecture (Bronze/Silver/Gold)?

#Medallion #Data Lake

Practice

Data Engineer • Technical • medium

How do you implement data quality checks in a production pipeline?

#Great Expectations #Data Validation

Practice

Data Engineer • Technical • medium

What is data lineage and why is it important? How do you implement it?

#Lineage #Metadata

Practice

Data Engineer • Technical • hard

How would you detect and handle data drift in a production system?

#Data Drift #Monitoring

Practice

Data Engineer • Technical • medium

What is PII (Personally Identifiable Information) and how do you handle it in a data pipeline?

#PII #Privacy #Compliance

Practice

Data Engineer • Technical • medium

Explain the concept of a data catalog. What tools have you used?

#Data Catalog #Metadata

Practice

Data Engineer • Technical • hard

Compare AWS Redshift, Google BigQuery, and Snowflake for a petabyte-scale warehouse.

#Redshift #BigQuery #Snowflake

Practice

Data Engineer • Technical • hard

How does BigQuery handle large joins efficiently? What is its columnar storage approach?

#BigQuery #Columnar Storage

Practice

Data Engineer • Technical • medium

Explain the difference between S3, HDFS, and GCS for data storage.

#S3 #HDFS #GCS

Practice

Data Engineer • Technical • medium

How would you reduce costs in a cloud-based data platform?

#Cloud #Cost

Practice

Data Engineer • Technical • medium

What is infrastructure as code (IaC)? Have you used Terraform for data infrastructure?

#Terraform #IaC

Practice

Data Engineer • Technical • medium

Explain the difference between OLAP and OLTP systems. When would you use each?

#OLAP #OLTP #Databases

Practice

Data Engineer • Technical • hard

What is a slowly changing dimension (SCD)? Describe SCD Type 1, 2, and 3 with examples.

#SCD #Dimensional Modeling

Practice

Data Engineer • Technical • hard

How would you optimize a SQL query that is running slowly on a 1 billion row table?

#Query Optimization #Indexing

Practice

Data Engineer • Technical • medium

Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER().

#Window Functions #SQL

Practice

Data Engineer • Technical • medium

What is a materialized view? How does it differ from a regular view?

#Materialized Views #Performance

Practice

Data Engineer • Technical • hard

Describe partitioning strategies in a data warehouse. When would you use range vs hash partitioning?

#Partitioning #Performance

Practice

Data Engineer • Technical • medium

What are CTEs (Common Table Expressions) and how do they differ from subqueries?

#CTEs #SQL

Practice

Data Engineer • Technical • medium

Explain ACID properties. Which databases sacrifice ACID for performance and why?

#ACID #Distributed Systems

Practice

Data Engineer • Technical • hard

How do you handle late-arriving data in a streaming pipeline?

#Kafka #Watermarks

Practice

Data Engineer • Technical • medium

What is idempotency and why is it critical in data pipelines?

#Idempotency #Data Quality

Practice

Data Engineer • Technical • hard

Explain the Lambda architecture. What are its tradeoffs vs Kappa architecture?

#Lambda #Kappa #Streaming

Practice

Data Engineer • Technical • hard

What is backfilling? How do you handle a backfill of 2 years of historical data without impacting production?

#Backfill #Airflow

Practice

Data Engineer • Technical • medium

Describe how you'd implement circuit breakers in a data pipeline.

#Circuit Breakers #Fault Tolerance

Practice

Data Engineer • Technical • medium

How do you monitor data pipeline health in production? What metrics do you track?

#Monitoring #Alerting

Practice

Data Engineer • Technical • medium

What is Apache Airflow? How does it differ from Prefect or Dagster?

#Airflow #Prefect #Dagster

Practice

Data Engineer • Technical • easy

Explain the difference between push-based and pull-based data ingestion.

#Push #Pull #CDC

Practice

Data Engineer • Technical • hard

Explain how Apache Spark's execution model works. What is a DAG in Spark?

#Spark #DAG #Distributed Computing

Practice

Data Engineer • Technical • hard

What is data skew in Spark? How do you diagnose and fix it?

#Data Skew #Performance

Practice

Data Engineer • Technical • hard

Explain the difference between map-side and reduce-side joins in MapReduce/Spark.

#Joins #MapReduce

Practice

Data Engineer • Technical • medium

What is Apache Kafka? Explain topics, partitions, consumer groups, and offsets.

#Kafka #Streaming

Practice

Data Engineer • Technical • medium

How does Kafka handle message ordering guarantees?

#Ordering #Partitions

Practice

Data Engineer • Technical • medium

What is the CAP theorem? Give an example of a real-world system tradeoff.

#CAP #Consistency #Availability

Practice

Data Engineer • Technical • medium

Explain how Parquet and ORC file formats work and when you'd use each.

#Parquet #ORC #Columnar

Practice

Data Engineer • Technical • hard

What is Delta Lake? How does it provide ACID transactions on data lakes?

#Delta Lake #ACID #Time Travel

Practice

Data Engineer • Technical • medium

Explain compaction in Delta Lake / Iceberg. Why is it important?

#Compaction #Performance

Practice

Data Engineer • Technical • medium

What is the star schema vs snowflake schema? When would you use each?

#Star Schema #Snowflake Schema

Practice

Data Engineer • Technical • hard

How would you model and optimize a BigQuery dataset for petabyte-scale ad-click attribution?

#BigQuery #Attribution

Practice

Data Engineer • Technical • hard

Explain how Google Spanner achieves global consistency with TrueTime.

#Spanner #TrueTime

Practice

Data Engineer • Technical • hard

How would you use Dataflow (Apache Beam) for a streaming aggregation job?

#Dataflow #Beam

Practice

Data Engineer • Technical • hard

What is Bigtable? When would you choose it over BigQuery?

#Bigtable #GCP

Practice

Data Engineer • Technical • medium

How do you optimize BigQuery costs for ad-hoc analytical queries?

#Cost #Optimization

Practice

Data Engineer • Technical • medium

In Apache Beam or Google Cloud Dataflow, how do you handle late-arriving data in a windowed streaming pipeline?

#Streaming #Watermarks #Late Data #Apache Beam

Practice

Data Engineer • Technical • medium

Explain the difference between partitioning and clustering in BigQuery. When would you use one over the other, and when would you use both?

#BigQuery #Partitioning #Clustering #Optimization

Practice

Data Engineer • Technical • hard

You have a PySpark job running on Dataproc that joins a massive user table with a smaller transaction table. The job is taking hours and failing with OOM errors due to data skew. How do you optimize it?

#Spark #Data Skew #Salting #Performance Tuning

Practice

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