Raiffeisenbank Machine Learning Engineer Interview Experience — 22 Questions from TF-IDF to RAG

Raiffeisenbank·Machine Learning Engineer·Apr 2026
Technical Screenhard
  • Briefly tell us about yourself and one of your most interesting projects.
  • Implement a class or function that, given a corpus of strings, computes TF-IDF.
  • How would you store and optimize TF-IDF with 10 thousand documents and a vocabulary of several million words? What sparse matrix formats exist?
  • What are the time and space complexity of fit and transform in TF-IDF?
  • What is the GIL, and is there parallelism in Python?
  • There are two dense NumPy matrices of 2 GB each; they need to be multiplied on a machine with 8 GB of RAM. Will the computation fit in memory, and how will it be executed?
  • What is the difference between asynchrony and multithreading, and when is each better to use?
  • What is a decorator in Python?
  • Write a try/retry decorator that will repeatedly execute any function until it completes successfully.
  • How does Word2Vec work, how is it trained, and what is fed as input? What architecture does it have?
  • In Word2Vec, will the word "castle" have the same vector in the sentences "I opened the castle" and "I went into the castle"?
  • How can the problem of homonymy in static embeddings before attention and BERT be solved?
  • What is GloVe and what is its essence?
  • How does self-attention work, and what is its asymptotic complexity in time and memory?
  • What is FlashAttention, how is it better than ordinary attention, and does it improve time, memory, or both parameters?
  • What is PagedAttention, and how does it optimize memory usage?
  • How does a transformer take word order into account, and how is RoPE applied in code?
  • What is the difference between a bi-encoder and a cross-encoder, and when should each be used?
  • What is LoRA and why is it needed?
  • Calculate the number of parameters of a LoRA adapter for a 500x1000 matrix with rank=8.
  • How would you estimate the size of a LoRA adapter for a model with approximately 1 billion parameters at rank=8?
  • What types of search are used in RAG, and what are the advantages and disadvantages of each?

Published

Curated and edited by PracHub

Practice the questions from this interview

Discussion

Sign in to join the discussion. The author is notified of every comment.

Loading comments…

Interview at a glance

Company
Raiffeisenbank
Role
Machine Learning Engineer
Rounds
Technical Screen
Difficulty
hard
Interview date
Apr 2026
Questions from this interview
8 questions

Related interview experiences

Explore more interview rounds, questions, and outcomes.

Browse interview experiences