Data Engineer 路 Intern to senior
Data engineering interviews lean heavily on SQL and Python. Expect to write queries by hand, explain how indexes and transactions work, and discuss how data is modelled and partitioned at scale.
64 questions
Both integrate changes from one branch into another: merge keeps both histories and joins them with a merge commit, while rebase rewrites your commits so they appear on top of the target branch, giving a linear history.
Open the conflicted files, decide what the final code should be between the conflict markers, remove the markers, run the tests, then stage the files and continue the merge or rebase.
Choose a real project with a technical or organisational challenge, explain your specific role and decisions with the STAR method, and finish with the result and what you learned.
Walk through how you noticed the issue, limited the impact, found the root cause, fixed it, and what you changed afterwards so the same class of bug could not happen again.
Choose a real mistake, take ownership, explain the impact, what you did to recover, and what you changed so it would not happen again.
Describe feedback that was uncomfortable but useful, explain how you responded, and show the measurable or observable improvement that followed.
Choose a genuine failure, explain why it failed, what you owned, how you recovered, and what you changed in future projects.
Show how you prioritized the essential outcome, communicated trade-offs, reduced risk and delivered without pretending everything could be done.
Show that you can defend a technical decision with evidence while remaining open to a better argument.
Keep the answer professional and future-focused: explain what you are looking for next without attacking your current or former employer.
ACID stands for Atomicity, Consistency, Isolation and Durability: a transaction either fully succeeds or fully fails, keeps the data valid, does not interfere with other transactions, and survives crashes once committed.
An index is a separate sorted data structure (usually a B-tree) that lets the database find rows without scanning the whole table, at the cost of extra storage and slower writes.
A clustered index defines the physical order in which the table's rows are stored, so there can be only one per table, while a non-clustered index is a separate structure that points back to the rows.
A decorator is a function that takes another function and returns a modified version of it, letting you add behaviour such as logging, caching or access control without changing the original code.
A generator is a function that uses yield to produce values one at a time and remembers its state between calls, so it can process large or infinite sequences without holding everything in memory.
CPython frees objects mainly through reference counting, deleting an object as soon as nothing refers to it, and uses a cyclic garbage collector to clean up groups of objects that reference each other.
Choose SQL when your data is relational and you need transactions, joins and strong consistency; choose NoSQL when you need flexible schemas, very high write throughput or horizontal scaling for a specific access pattern.
git revert creates a new commit that undoes an earlier one and is safe on shared branches; git reset moves the branch pointer back to an earlier commit, effectively removing later commits from that branch鈥檚 history.
Describe a real technical or process disagreement, show that you listened and argued with evidence rather than opinion, explain how a decision was reached, and how you supported it afterwards even if it was not your idea.
Describe a problem you noticed, why you decided to act, how you coordinated with others, and the impact of taking ownership.