All 78 questions
What is the difference between a data lake and a data warehouse?
Asked in 5 of 274 interviews · last asked Oct 9 · Concept · Junior
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A data lake stores data in many formats, often before it is cleaned or modeled. A data warehouse stores organized data built for reporting and analysis. Lakes offer flexibility for exploration and machine learning, while warehouses make business reporting easier; modern systems can support both roles.
- Lakes can hold raw files, logs, images, and structured tables.
- Warehouses usually hold cleaned, modeled data with consistent business definitions.
- Lakes often apply structure when reading; warehouses usually define structure before loading.
- Both need data quality checks, access controls, and clear ownership.
What the interviewer checks: The interviewer is checking whether you can match storage and modeling choices to how data will be used.
Other ways it was asked
- “What is the basic difference between a data lake and a data warehouse?”
- “What is the difference between a data warehouse and a data lake?”
- “What is the difference between a database and a data warehouse?”
What is the difference between OLTP and OLAP systems?
Asked in 4 of 274 interviews · last asked Sep 18 · Concept · Junior
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OLTP systems handle daily transactions, such as orders and payments. They support many short reads and writes, often using normalized tables. OLAP systems support reports and analysis with large scans and summaries, often using star schemas. OLTP focuses on fast, reliable transactions; OLAP focuses on efficient analysis.
- OLTP means online transaction processing; OLAP means online analytical processing.
- OLTP usually works with current operational data; OLAP often combines historical data from several sources.
- OLTP queries usually touch few rows; OLAP queries often aggregate many rows.
- Normalized tables and star schemas are common choices, not strict requirements.
What the interviewer checks: The interviewer checks whether you can link each workload to its query patterns and data model.
Other ways it was asked
- “What is the difference between OLAP and OLTP?”
- “What are OLAP and OLTP systems, and how do they differ?”
- “What's the difference between OLAP and OLTP?”
What is medallion architecture, and what are the bronze, silver, and gold layers?
Asked in 4 of 274 interviews · last asked Oct 24 · Concept · Mid-level
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Medallion architecture organizes data into layers with increasing quality and readiness for use. Bronze stores raw data as received from sources. Silver cleans, validates, and combines data into reliable records. Gold shapes data for business needs, such as reports, dashboards, and analysis.
- Bronze keeps source data so it can be traced and processed again.
- Silver handles duplicates, data types, missing values, and other quality issues.
- Gold often contains business metrics, summary tables, or dimensional models.
- The layers describe data quality and purpose, not a required database technology.
What the interviewer checks: The interviewer is checking whether you understand how raw data becomes trusted, business-ready data.
Other ways it was asked
- “What is medallion architecture, and how does it work?”
- “What is a medallion architecture, and how do its layers organize data?”
- “What is the medallion architecture for data processing?”
What is a data warehouse?
Asked in 3 of 274 interviews · last asked Oct 19 · Concept · Junior
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A data warehouse is a system that stores data for reporting and analysis. It brings together cleaned data from different sources and keeps historical records. It is designed for analytical queries rather than day-to-day tasks such as placing orders.
- Combines data from multiple sources using consistent definitions and formats.
- Keeps historical data to support trend analysis.
- Supports reporting and complex queries, rather than routine transaction processing.
What the interviewer checks: The interviewer is checking whether you understand a data warehouse’s purpose and how it differs from a transaction database.
How do a record’s schema and content change through the bronze, silver, and gold layers?
Asked in 2 of 274 interviews · last asked Sep 17 · Concept · Mid-level
Other ways it was asked
- “What changes to a record as it moves through the three layers of the medallion architecture?”
- “What are the concrete differences in schema and content between the silver and gold layers of a table in a medallion architecture?”
- “What preprocessing steps are typically performed in the silver layer of a medallion architecture?”
What is your product vision for a data platform, specifically around data management?
Asked once · last asked Sep 7 · Senior
Other ways it was asked
- “What would be your product vision for a data platform, including data management and datasets?”
What is your approach to providing an end-to-end data warehouse solution for a client?
Asked once · last asked Sep 19 · Design · Mid-level
Other ways it was asked
- “What would be your approach to implementing a data warehouse from scratch and delivering an end-to-end solution?”
How would you create a healthcare data warehouse?
Asked once · last asked Sep 19 · Design · Mid-level
Other ways it was asked
- “How would you create a healthcare data warehouse for a client?”
- “How do you create a data warehouse?”
What is a data mart, and why can it make queries faster?
Asked once · last asked Sep 19 · Concept · Junior
Other ways it was asked
- “What is a data mart, and why is it faster?”
- “Why are data marts faster?”
What criteria would you use to choose Snowflake over other data warehouse solutions?
Asked once · last asked Sep 20 · Scenario · Mid-level
What source types and data models, such as fact, dimension, and event tables, are commonly used in data pipelines?
Asked once · last asked Mar 3 · Concept · Mid-level
What data-loading patterns do you know for loading raw data into a warehouse?
Asked once · last asked Mar 20 · Concept · Mid-level
What is columnar storage, and why is it commonly used in data warehouses?
Asked once · last asked Apr 14 · Concept · Mid-level
What is the Data Vault modeling approach, and when would you use it?
Asked once · last asked Apr 17 · Concept · Senior
How would you design a CDC pipeline using medallion architecture for nightly data from different transactional databases, including processing and best practices at the bronze, silver, and gold layers?
Asked once · last asked Apr 24 · Design · Senior
Other ways it was asked
- “How would you design a CDC data pipeline using medallion architecture for nightly data from different transactional databases, and what would you do at each layer—from the raw bronze layer through silver to gold? What best practices would you follow?”
What types of operations are performed in online analytical mining (OLAM)?
Asked once · last asked May 2 · Concept · Mid-level
What is the medallion architecture, and why is it preferred over a traditional flat data lake?
Asked once · last asked May 9 · Concept · Mid-level
Could you describe the typical stages of a simple batch ETL pipeline that loads data from a relational database into a data warehouse table? What happens in the extract, transform, and load phases?
Asked once · last asked May 18 · Concept · Junior
How would you design a data platform architecture, define its goals, and evaluate whether it meets them?
Asked once · last asked Jun 3 · Design · Senior
Other ways it was asked
- “Describe a data platform architecture you designed, including its goals and how you evaluated whether it met them.”
How is a lakehouse different from a data warehouse?
Asked once · last asked Jun 9 · Concept · Mid-level
What design artifacts would you produce for a data platform architecture project, and which stakeholders would you present them to?
Asked once · last asked Jun 16 · Senior
Other ways it was asked
- “What design artifacts did you produce for a data platform architecture project, and which stakeholders did you present them to?”
When would you virtualize on-premises Oracle data with a tool such as Denodo, and when would you physically ingest it into a lakehouse?
Asked once · last asked Jun 16 · Design · Senior
How would you use Azure, AWS, or GCP to manage data infrastructure, and which data services or storage options would you choose?
Asked once · last asked Jun 24 · Tooling · Mid-level
Other ways it was asked
- “How have you used Azure, AWS, or GCP to manage data infrastructure, and which data services or storage options did you use?”
How would you work with end users to design data models within a medallion architecture using dbt?
Asked once · last asked Jul 16 · Scenario · Senior
How would you build a data mesh across data platforms?
Asked once · last asked Jul 16 · Design · Senior
How would you design a CDC pipeline that ingests data from a streaming source such as Kafka or Flink and lands it in Delta Lake or Apache Iceberg?
Asked once · last asked Jul 16 · Design · Senior
When would you recommend Data Vault modeling, and how would you implement it within a medallion architecture?
Asked once · last asked Jul 16 · Design · Senior
Other ways it was asked
- “When would you suggest using data vault, and how would you implement that within medallion?”
How do you decide whether an enterprise-wide architecture or a business-area-specific architecture is appropriate?
Asked once · last asked Jul 16 · Design · Senior
Tell me about a time you translated a data strategy into an aligned architecture and design.
Asked once · last asked Jul 16 · Behavioral · Senior
How do you determine the data storage architecture for a dataset?
Asked once · last asked Jul 16 · Design · Senior
How would you use dbt to implement silver-to-gold transformations in a Databricks-orchestrated data platform?
Asked once · last asked Jul 28 · Scenario · Senior
How do you compare Databricks and Snowflake as data platforms, and where does Delta Lake fit?
Asked once · last asked Jul 29 · Design · Senior
When would you store data in a row-based relational database versus a columnar database?
Asked once · last asked Jul 29 · Concept · Mid-level
Other ways it was asked
- “When would you store data in a rule-based RDBMS style versus a columnar database?”
How would you design a solution to load and query petabytes of data stored in Azure Data Lake using Azure Synapse Analytics, including data structure, query performance, and schema evolution?
Asked once · last asked Aug 11 · Design · Senior
How would you characterize data stored in Snowflake: operational OLTP data, analytical OLAP data, or another form?
Asked once · last asked Aug 14 · Concept · Mid-level
How would you approach migrating a data warehouse from Teradata to Snowflake?
Asked once · last asked Aug 20 · Scenario · Senior
What would you do differently if you led a data warehouse migration again?
Asked once · last asked Aug 20 · Behavioral
How do you implement incremental load from bronze to silver layer?
Asked once · last asked Aug 25 · Scenario · Mid-level
What operations and transformations are typically performed when moving data from the Bronze layer to Silver and then to Gold?
Asked once · last asked Aug 25 · Concept · Mid-level
How would you separate analytical, machine learning, and reporting data in a data architecture, and create a semantic layer for each?
Asked once · last asked Aug 26 · Design · Senior
How would you design an SAP data architecture when firm business requirements have not yet been defined?
Asked once · last asked Aug 28 · Design · Senior
How would you architect a cloud data platform, organize its data lake, and support different types of data consumers?
Asked once · last asked Aug 31 · Design · Senior
Other ways it was asked
- “Can you tell me about a cloud data platform you personally architected or helped build? How did you organize the data lake and support different types of data consumers?”
How do you migrate from a JSON blob per user to a relational model for analytics?
Asked once · last asked Sep 3 · Scenario · Senior
How would you roll out a Snowflake migration from single-tenant databases to multi-tenant tables across all clients?
Asked once · last asked Sep 9 · Design · Senior
What are the trade-offs between using Spark and running queries directly in a database engine such as Snowflake, BigQuery, or Redshift?
Asked once · last asked Sep 10 · Scenario · Senior
What are the drawbacks of storing all data in a single layer rather than separating it into Silver and Gold layers?
Asked once · last asked Sep 16 · Concept · Mid-level
What are the benefits of a layered data architecture compared with a single-layer approach?
Asked once · last asked Sep 16 · Concept · Mid-level
How would you design a solution to migrate nonstandardized Snowflake data on AWS to Azure using CDC Replicate and a medallion architecture?
Asked once · last asked Sep 16 · Design · Senior
How do the intermediate and mart layers work in dbt?
Asked once · last asked Sep 17 · Concept · Mid-level
What would be your approach to creating a data mart from an existing data warehouse?
Asked once · last asked Sep 19 · Design · Mid-level
How would you plan data migration and database architecture during a technology-stack migration?
Asked once · last asked Sep 21 · Scenario · Senior
Tell me about a data engineering project you delivered, from the original business problem through the pipeline, data model, and validation. What parts were you personally responsible for?
Asked once · last asked Sep 21 · Behavioral · Mid-level
Walk me through a data engineering project from the business problem through ingestion, transformation, data modeling, and validation.
Asked once · last asked Sep 22 · Behavioral · Mid-level
How would you organize the architecture and different data layers in Snowflake?
Asked once · last asked Sep 22 · Design · Mid-level
How do you design the ingestion, refined, and exchange layers in BigQuery, and how do you handle partitioning, clustering, and query performance?
Asked once · last asked Sep 23 · Design · Senior
How would you qualify, unify, load, and secure high-volume data for dashboards and reporting?
Asked once · last asked Sep 30 · Design · Senior
How would you structure a dbt project into layers?
Asked once · last asked Oct 2 · Design · Mid-level
Other ways it was asked
- “Can you take me through the sample architecture of a dbt project? How is a dbt project layered?”
In a layered data lake, what belongs in each layer, which layer should BI consume from, and should a new business rule be implemented in the pipeline or in DAX?
Asked once · last asked Oct 2 · Design · Senior
How would you implement incremental loading for a huge table that cannot be reloaded every day?
Asked once · last asked Oct 7 · Scenario · Mid-level
What are the bronze, silver, and gold layers in medallion architecture?
Asked once · last asked Oct 24 · Concept · Mid-level
How do you fetch data from the bronze layer to the silver layer?
Asked once · last asked Aug 25 · Scenario · Mid-level
Other ways it was asked
- “How do you load the latest or updated data from the bronze layer to the silver layer?”
Is MongoDB a data lake, a data warehouse, or a different kind of database?
Asked once · last asked Mar 9 · Concept · Junior
What kinds of analysis can be performed using a data warehouse?
Asked once · last asked May 2 · Concept · Junior
What is another major type of database besides a transactional database?
Asked once · last asked May 2 · Concept · Junior
What artifacts should be included in a data architecture review package?
Asked once · last asked Jun 16 · Concept · Senior
What are some of the core principles that underpin a data mesh?
Asked once · last asked Jul 16 · Concept · Mid-level
In a data mesh, can a consumer of one data product be another data product or domain?
Asked once · last asked Jul 16 · Concept · Mid-level
When implementing dbt gold-layer transformations, how do you work with models that are already in place?
Asked once · last asked Jul 28 · Scenario · Mid-level
Who typically consumes data in the Gold layer of a medallion architecture?
Asked once · last asked Aug 25 · Concept · Junior
What are the key characteristics of big data, particularly the big Vs?
Asked once · last asked Aug 27 · Concept · Junior
What is the difference between big data and traditional data analysis?
Asked once · last asked Aug 27 · Concept · Junior
Why do we use a data mart?
Asked once · last asked Sep 18 · Concept · Junior
Can you tell me generally what Kimball principles and dbt are?
Asked once · last asked Sep 29 · Concept · Junior
Is dbt a tool that uses Kimball principles and turns them into SQL?
Asked once · last asked Sep 29 · Concept · Junior
What is big data?
Asked once · last asked Oct 12 · Concept · Junior
In a layered data architecture, what purpose do the layers serve, and how would you implement them?
Asked once · last asked Oct 18 · Concept · Mid-level
How would you load cleaned data into a data warehouse?
Asked once · last asked Oct 18 · Scenario · Mid-level
Which layer of medallion architecture would you prioritize for testing, and why?
Asked once · last asked Oct 24 · Scenario · Mid-level
More Data Modeling interview questions
- All Data Modeling interview questions
- Data Modeling Basics Interview Questions
- Database Schema Design Interview Questions
- Lakehouse, Apache Iceberg, and Delta Lake Interview Questions
- Semantic Modeling and Power BI Interview Questions
- Data Quality and Governance Interview Questions
How this list is made
Every question here was asked by a real interviewer in a real job interview that a candidate ran MeetAssist in. After the call, the interviewer's questions are pulled from the transcript. Practice sessions, tests, exams and anything that was not a job interview are dropped.
Questions are rewritten so they make sense on their own: names of people, employers and clients are removed, and speech-to-text mistakes are fixed. Small talk, logistics and questions about one candidate's own résumé are left out. Rephrasings of the same question are merged, and the count is the number of different interviews it came up in.
The interviews come from candidates who use MeetAssist, so they lean towards software, data and AI roles: the shares describe these interviews, not every Data Modeling interview. Answers to the most asked questions are written and checked by an editor; a "common mistake" is shown only when reviews of real answers in these interviews show it, with the count.
274 interviews, 168 candidates, Dec 2025 to Oct 2026. Updated every month with new interviews.
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