Delta Lake Interview Questions

10 real Delta Lake questions asked in live technical interviews — each with a model answer. Updated weekly.

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These Delta Lake interview questions were captured from real interviews by candidates using Assisting AI. Each links to a full model answer. For real-time help during your own interview, get Assisting AI from ₹500/day.

What is the difference between Delta Lake and a lakehouse?🟡 Medium · Conceptual · Asked 1×What is the difference between a data warehouse, Delta Lake, a data lake, and a data lakehouse?🟡 Medium · Conceptual · Asked 1×These are technology stack questions. I'm asking: When storing data, which format do you choose? In Snowflake, you can store data in native Snowflake format or Iceberg. In Databricks, you can store data in Delta Lake or Iceberg. Which format would you pick and why?🟡 Medium · Conceptual · Asked 1×What is the difference between a normal Delta table and a Delta Live Table?🟡 Medium · Conceptual · Asked 1×We have a Delta table `retail_prod.analytics.sales_silver` that is about 600 GB. It is partitioned by `event_date` (daily) and contains many small files (5–20 MB) with no Z‑Order. Dashboards filter on the last 30 days of `event_date` and `merchant_id`, and the p95 query time is above 12 seconds. We cannot change the upstream schema. How can we bring the p95 query time under 12 seconds for the 30‑day window?🟡 Medium · Conceptual · Asked 1×A Delta‑backed star schema joins one large fact table with several small dimension tables on equality keys. What SQL tactic usually gives the best first‑step speedup?🟡 Medium · Conceptual · Asked 1×Downstream consumers require incremental changes from a Delta table that includes deletes and updates. You must deliver ordered change data capture (CDC) from version checkpoints. Which Delta feature should you use?🟡 Medium · Conceptual · Asked 1×You are planning schema evolution where columns may be added and reordered. You want reliable column mapping for long‑term merges. Which setting is appropriate?🟡 Medium · Conceptual · Asked 1×Analysts filter a 2‑TB Delta table by event_date and customer_id. You see high data‑skipping misses due to out‑of‑order loads. What is the most targeted improvement?🟡 Medium · Conceptual · Asked 1×Can you tell me what vacuum is in Databricks?🟡 Medium · Conceptual · Asked 1×

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