PKO Bank Polski interview questions

After CV stage I had an interview. The questions included difference between Data Scientist and Data Engineer, lambda functions in Python, primary key in relational data bases. I also got question about projects with data bases.

Stage 1: HR Screening (30 min) Intro to the company and the team Questions about previous experience and projects Availability, salary expectations, relocation/remote preferences Stage 2: Technical Interview #1 — System Design (60 min) Design a simplified banking transaction system (accounts, balances, transfers) Focus on scalability, data consistency, error handling Discuss choices: DB, caching, microservices vs monolith Stage 3: Technical Interview #2 — Coding (60 min) Live coding: REST API for basic account management (CRUD) Use preferred language (Java, Go, Python, etc.) Emphasis on clean code, error handling, tests