Real Interview Questions

If we store transaction details in Kafka and consume them later, even with partitioning, is that enough? How many resources will this consume?

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Kafka Messaging Scalability

🟡 Medium Conceptual Mid Asked 1× May 2026

The question remains: we don't have a time‑based key. Person T1 receives a transaction; Person T2 should immediately know about T1's transaction.

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Event-driven Real-time Data Consistency

🟡 Medium Conceptual Mid Asked 1× May 2026

Will a partition be based on region, occupation, and amount?

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Partitioning Databases

🟡 Medium Conceptual Junior Asked 1× May 2026

Design a data pipeline.

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Data Engineering Etl Pipeline

🟡 Medium System Design Mid Asked 1× May 2026

Suppose a user sends a money transfer transaction today. By the next second there will be 600,000 entries in the queue. After all those entries are processed, the system will listen to the transaction, but it doesn’t happen. How would you design the system to ensure immediate notification of transaction status to the sender and receiver?

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Kafka Real-time Notification Distributed Systems

🔴 Hard System Design Senior Asked 1× May 2026

Will Postgres be able to handle traffic?

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Postgres Database Scaling

🟡 Medium Conceptual Junior Asked 1× May 2026

Are we going to have one Postgres database with one table for transactions? We will keep writing to the transaction table, about 5 to 7 million transactions per second. Will Postgres handle this?

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Postgres Database Performance High Throughput

🔴 Hard Conceptual Senior Asked 1× May 2026

You are collecting metrics and want to trigger email alerts when thresholds are reached. What tools do you use for this?

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Monitoring Alerting Metrics

🟡 Medium Conceptual Junior Asked 1× May 2026

What are the benefits of AI‑assisted coding tools?

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Ai Coding Tools Productivity

🟢 Easy Conceptual Fresher Asked 1× May 2026

What is middleware in Node.js?

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Nodejs Middleware

🟢 Easy Conceptual Junior Asked 1× May 2026

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?

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Delta Lake Data Skipping Databricks

🟡 Medium Conceptual Mid Asked 1× May 2026

Your payments producer is hitting a hot shard on Kinesis Data Streams during peak hours, causing iterator age spikes and throttling. Within a 15‑minute mitigation window, what steps would you take to stabilize throughput (e.g., split shards, use temporary randomized sub‑keys) and what is your long‑term keying strategy to prevent recurrence while keeping ordering guarantees where needed?

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Kinesis Data Streams Sharding Throughput

🟡 Medium Debugging Mid Asked 1× May 2026

You need to pull 200 million rows from a source JDBC system into Databricks. The current PySpark job uses a single partition and exhausts the driver. How would you redesign the read for parallelism (choose a partitionColumn, set lowerBound/upperBound/numPartitions, handle nulls/outliers, tune fetch size) and ensure the ingest is idempotent before writing to Bronze?

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Pyspark Jdbc Databricks

🟡 Medium Coding Mid Asked 1× May 2026

Your Databricks jobs were migrated to Unity Catalog last week. A nightly Silver write is failing because the storage credential has rotated, and you cannot change IAM roles tonight. How do you restore the write within the same window, considering Unity Catalog grants on the storage credential, external location, object ownership on `catalog.schema.table`, and job cluster access mode, while keeping auditability intact?

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Unity Catalog Databricks Iam

🔴 Hard Debugging Senior Asked 1× May 2026

You are orchestrating a 5‑task lakehouse workflow where Task A discovers a partition path (e.g., s3://raw/yyyyymmdd=20231015) that downstream tasks must use. Finance wants ephemeral, policy‑restricted compute and parallel fan‑out where possible. Which Databricks pattern best fits?

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Databricks Lakehouse Workflow Job Clusters

🟡 Medium Conceptual Junior Asked 1× May 2026

A Bronze to Silver pipeline needs data quality rules that drop invalid rows yet record metrics for monitoring. Stakeholders want declarative checks and managed lineage without hand‑coding UDF logic. What should you choose?

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Delta Live Tables Data Quality Data Pipeline

🟡 Medium Conceptual Junior Asked 1× May 2026

You must implement near‑real‑time ingestion from S3 with schema drift (occasional new columns) while avoiding full listings of the bucket. Badly formed records should land in a quarantine column for triage.

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Auto Loader S3 Schema Evolution Data Ingestion

🟡 Medium Conceptual Junior Asked 1× May 2026

Your team wants repeatable library code for transformations across jobs and clusters. What packaging and deployment approach is most maintainable on Databricks?

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Databricks Python Packaging Libraries Devops

🟡 Medium Conceptual Mid Asked 1× May 2026

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?

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Delta Lake Star Schema Broadcast Join

🟡 Medium Conceptual Senior Asked 1× May 2026

You need the latest record per (id) from a change‑log table with multiple updates per day and occasional ties on timestamp. Which SQL pattern is most reliable?

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Window Functions Row Number Change Log

🟡 Medium Conceptual Senior Asked 1× May 2026