Code search indexing
Design the indexing subsystem for a code-search engine over 100M repositories (~2B files, 50TB of source). It must support exact substring/regex-ish matches plus symbol search, ingest pushes within minutes of a commit, and handle that 30% of files change weekly. Query p95 under 500ms across the corpus.
What a strong answer looks like
Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts (data model, bottlenecks, consistency, failure modes) and name the trade-offs you are making.
Clarify5:30 left
Estimate5:30 planned
Design16:30 planned
Deep dive13:30 planned
Failure9:00 planned
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.