S3 Interview Questions

25 real S3 questions asked in live technical interviews — each with a model answer. Updated weekly.

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Are you using a specific S3 blob storage cloud provider? Do you store information in the pipeline?🟡 Medium · Conceptual · Asked 1×Let's say we are doing data backup on S3 storage and it's taking a lot of time. How would you mitigate this issue? What approaches would you have?🟡 Medium · Conceptual · Asked 1×We have a raw folder in an S3 bucket and want to perform data cleansing. How would you identify duplicates in a particular file?🟡 Medium · Conceptual · Asked 1×Suppose you have a lot of files in a folder in an S3 bucket and want to move all files into a B folder. How would you do that?🟡 Medium · Coding · Asked 1×Based on your resume, can you explain a project where you performed data ingestion using Glue, S3, Step Functions, and API Gateway?🟡 Medium · Behavioral · Asked 1×In a scenario where a file is written into S3, how would you trigger an AWS Glue job that takes the file as an input argument? What steps would you follow?🟡 Medium · Conceptual · Asked 1×Let me give a scenario: we have a market file in S3 and want to load the data into our cluster. How would you load it?🟡 Medium · Coding · Asked 1×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.🟡 Medium · Conceptual · Asked 1×Have you worked on any cloud architecture designs, particularly for basic S3 ETL purposes?🟡 Medium · System Design · Asked 1×A pipeline ingests data into an ISO table every hour. Over six months, query performance has dropped and S3 storage cost has spiked due to millions of tiny metadata files. What approach would reduce cost and improve pipeline performance?🔴 Hard · System Design · Asked 1×Given a scenario where files are coming into an S3 bucket and need to be loaded into Redshift, but the files sometimes change their schema, how would you establish dynamic schema enforcement?🟡 Medium · Conceptual · Asked 1×Explain the different techniques for moving data from S3 to Redshift.🟡 Medium · Conceptual · Asked 1×Currently data is present on S3; how would you move it into Redshift?🟡 Medium · Conceptual · Asked 1×We process a large amount of data daily, receiving files every second or minute. We currently move files to another folder or bucket. Is there an optimized solution for this file transfer?🟡 Medium · Conceptual · Asked 1×When a file is uploaded, an event triggers a second function. How can we design this event‑driven flow in AWS?🟢 Easy · Conceptual · Asked 1×What are the three layers of buckets in a data lake, and how does an S3 event trigger an AWS Glue job that cleans data and loads it into the silver layer?🟡 Medium · Conceptual · Asked 1×I understand the complete pipeline again. I'm asking the same question: Is there an optimized solution to avoid dropping a completion status file to an S3 folder, and instead trigger a second Glue function from the first one?🟡 Medium · Conceptual · Asked 1×How do you copy a file from one S3 location to another S3 location?🟢 Easy · Conceptual · Asked 1×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.🟡 Medium · Conceptual · Asked 1×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. Which design is most appropriate on Databricks?🟡 Medium · Conceptual · Asked 1×What is the maximum bucket size one can have on Amazon S3?🟢 Easy · Conceptual · Asked 1×Can you tell me about lifecycle policies in Amazon S3?🟢 Easy · Conceptual · Asked 1×Are you saying the S3 bucket is KMS encrypted? When performing any S3 bucket operations, do you need to pass the KMS key every time? How are you going to handle that?🟡 Medium · Conceptual · Asked 1×You mentioned that you used an S3 bucket to write state. Do you know what type of encryption has been used?🟢 Easy · Conceptual · Asked 1×Suppose you are creating ETL pipelines that perform incremental loads. You have access to an S3 bucket where files are placed at regular intervals. How would you design the pipeline so that it automatically triggers on the latest file without performing a full load?🟡 Medium · Conceptual · Asked 1×

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