Python interview questions for data engineers
Collections, generators, OOP, concurrency, and memory basics. 35 questions with full answers, written for freshers. All topics
Collections & Basics (2)
Memory & Internals (1)
Python for Data Pipelines (12)
- Read a file bigger than memory
- Paginate through a REST API
- Handle API rate limits and retries
- Exception handling in ETL scripts
- Logging instead of print
- Connecting to a database safely
- Config and secrets management
- Unit testing a transformation function
- Dataclasses and Pydantic for records
- Working with dates and timezones
- Reading and writing JSON, CSV, Parquet
- Idempotent Python jobs
pandas & Polars (9)
Language Internals Interviewers Still Ask (11)
- Mutable default arguments
- __init__ vs __new__
- map, filter and reduce vs comprehensions
- Dictionary internals and lookup cost
- Remove duplicates while keeping order
- asyncio for I/O-bound ingestion
- concurrent.futures ThreadPool vs ProcessPool
- Pickling and its risks
- / vs // and % with negatives
- Packaging and dependency management
- Garbage collection and reference cycles