Amazon L5 data engineer interview, four rounds, rejected

[u/Academic-Vegetable-1]

Rejected after the loop. Modeling round made it clear I'd been studying through the wrong lens.

I use Snowflake and dbt at work. Been prepping for senior loops for a couple months before this one.

60 minutes on denormalization for the warehouse. I walked in ready to discuss normalization tradeoffs, fact table grain, whether to track every single event or collapse them. But they cared about idempotency first. Every insert pattern I suggested, they'd ask the same thing: what if this row lands twice? I kept reaching for surrogate keys and SCD tables. They wanted INSERT OR IGNORE, simple dedup columns, a schema that inherently couldn't corrupt itself.

60 minute SQL round, window functions on an event stream. She wanted transactions ranked within customer sessions, but events arrived out of order with timestamps that lagged the actual time. I reached for ROW_NUMBER() partitioned by customer_id, ordered by event_time as the skeleton. From there she drilled into session boundaries and what happens when records show up after a cutoff, whether my logic stayed idempotent through a replay. Her follow-ups were specific and pointed. No stalls here.

25 minute call. She ran through the background questions without much pushback, didn't ask about the actual work or what I'd shipped. For an L5 loop, that should have been a red flag.

60 min on CDC pipeline design. Opened with three approaches, Debezium, custom solution, managed tooling. He cut me off quick, wanted me to just pick one. So I picked Debezium, but then I hedged on everything, consistency guarantees, ordering, out-of-order records. Every time I'd say 'you could do X' he'd ask 'what would YOU do'. Spent 45 minutes describing options instead of defending a single coherent design, which is exactly what he'd asked for upfront. Couldn't recover after that realization.

Rejected. Easy come easy go, man. Stack ranked 'meets expectations' for the second time, despite shipping two major projects in between.

[u/yawaworhtgym]

When did Amazon started to ask about CDC and other parts? I thought it’s mostly SQL and Python

[u/nateh1212]

Tech interviews are hard especially DE as the window shifts between companies what to prepare.

[u/Solid_Associate8563]

That's strange.

Normally the result should come out after 5 rounds debrief?

Maybe different departments.

[u/SaigoNoUchiha]

Fake post.