wrapped up the HF DE loop three weeks ago. didn't get the offer but the process was thorough and i learned a lot from it, so here's the full breakdown.
applied through linkedin, got a recruiter reach out about 10 days later. the role was on the dataset infrastructure team, specifically around the Datasets library and large-scale ingestion pipelines for training data.
phone screen (45 min, engineer-led) not the recruiter screen i expected. it was directly with a senior engineer. we talked about my background for about 10 minutes, then dove into a short technical problem: design a deduplication pipeline for a large text corpus where you can't load the whole thing into memory. they wanted to hear about hashing approaches, bloom filters, streaming. nothing super exotic, but you need to actually know this stuff.
SQL round (60 min) two problems. one was pretty basic aggregation stuff (how many datasets have been downloaded more than X times in the last 30 days, grouped by language). the second was more involved: find model checkpoints where the fine-tune dataset had an overlap of > 5% with the eval set, given two tables, one for training data lineage and one for eval splits. the join logic was the tricky part. they use postgres.
system design (60 min) design a pipeline to continuously ingest and version new community-contributed datasets. they care about: idempotency, handling schema drift, tracking data provenance, and scalability. i spent time on the versioning layer and they seemed to appreciate that. they asked specifically about how you'd handle a contributor uploading malformed data without taking the whole pipeline down.
behavioral (45 min) with an EM. mostly about how you handle ambiguity and cross-team work. one question that tripped me up: "tell me about a time your pipeline broke in a way that affected a downstream team." have a specific story ready.
timeline: applied day 0, first call day 11, loop days 23-29 (spread across a week), heard back 9 days later. the speed was decent. comp range they mentioned was $160-195k base for a senior role, remote US.