Real Interview Questions

How do you think about schema design?

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Database Design Schema Design

🟡 Medium Conceptual Mid Asked 43× Jul 2026

Imagine an AWS pipeline that now has to serve an analytics team needing low-latency SQL access on curated data, while the source tables keep changing schema over time. How would you design the ingestion and transformation layer to handle schema evolution safely while keeping the SQL layer stable?

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Schema Evolution Aws Data Pipeline

🔴 Hard System Design Senior Asked 1× Jul 2026

An increasing cluster cost: how would you decide between changing partitioning, adjusting join strategy, and scaling the EMR cluster? What evidence would you use to choose the right fix? Additionally, imagine the same pipeline now has to ingest a new source for changing power. With occasional schema drift and the business still wants the load to keep running without manual intervention, how would you design the solution?

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Emr Cost Optimization Schema Evolution

🔴 Hard System Design Senior Asked 1× Jul 2026

A new column was added without informing the data team, causing the pipeline to fail. How would you prevent such situations?

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Data Engineering Data Pipelines Schema Management

🟡 Medium Conceptual Junior Asked 1× Jul 2026

What is the difference between a schema‑on‑write and a schema‑on‑read approach in data warehousing, and can you give an example of when you would use each?

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Data Warehousing Schema Design Data Lakes

🟢 Easy Conceptual Fresher Asked 1× Jul 2026

What is the difference between a star schema and a snowflake schema? Do you use them?

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Star Schema Snowflake Schema Data Warehousing

🟡 Medium Conceptual Mid Asked 1× Jul 2026

Suppose you have built a data model in the gold layer, and over time the solution has expanded into multiple tables, relationships, and complex logic. An enhancement requires changes to the gold layer. How would you approach this?

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Gold Layer Data Modeling Schema Evolution Data Lake Etl

🟡 Medium Conceptual Mid Asked 1× Jul 2026

Define a schema. Can you use a struct type to define a schema?

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Schema Definition Data Modeling Structs

🟢 Easy Conceptual Fresher Asked 1× Jul 2026

Can you tell how you would handle a schema violation?

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Database Schema Error Handling

🟡 Medium Conceptual Mid Asked 1× Jun 2026

Are you comfortable with data modeling? Do you understand data modeling techniques and star schemas? Have you had experience with them?

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Data Modeling Star Schema Database Design

🟡 Medium Conceptual Junior Asked 1× Jun 2026

How would you maintain backward compatibility when the unit of a sensor data column changes from millimeters to centimeters? How do you handle schema version control?

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Schema Evolution Data Versioning Backward Compatibility

🔴 Hard Conceptual Mid Asked 1× Jun 2026

How do you manage schema changes in time-series data? For example, if a pipeline suddenly receives five new columns, how would you handle that?

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Schema Management Time-series Data Data Pipelines

🟡 Medium Conceptual Junior Asked 1× Jun 2026

Why should you choose a star schema instead of a snowflake schema?

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Star Schema Snowflake Schema Data Warehousing

🟡 Medium Conceptual Junior Asked 1× Jun 2026

Does the employee table have columns employee id and employee name?

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Database Sql Schema Design

🟢 Easy Conceptual Junior Asked 1× Jun 2026

In Kafka, how can you evaluate schema changes from upstream so that adding or removing fields does not cause problems? Explain how backward and forward compatibility work and how to manage schema evolution without breaking downstream consumers.

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Kafka Schema Evolution Data Pipelines

🟡 Medium Conceptual Mid Asked 1× Jun 2026

I understand that CSV files are coming into an S3 bucket. What changes are needed to handle this situation?

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Aws S3 Data Ingestion Schema Evolution

🟡 Medium Conceptual Junior Asked 1× Jun 2026

Suppose multiple CSV files are coming daily into an S3 bucket, and sometimes the schema changes: new columns are added or data types change. How would you handle this situation in PySpark? Explain the steps and logic behind your approach.

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Pyspark Data Engineering Schema Evolution S3

🟡 Medium Conceptual Mid Asked 1× Jun 2026

What types of reference data have you used, and how did you incorporate them into a star schema? How did you handle deduplication and curating customer data?

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Reference Data Star Schema Data Deduplication Data Curating

🟡 Medium Conceptual Mid Asked 1× May 2026

What is the difference between Star Schemes and Snowflake Schemes?

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Data Modeling Star Schema Snowflake Schema

🟡 Medium Conceptual Junior Asked 1× May 2026

How would you modify columns such as modify date, creator date, quantity, order number, and SKU, and optionally drop a column named 'chat'?

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Database Ddl Schema Design

🟡 Medium Conceptual Junior Asked 1× May 2026