Genentech · Primly Community

Genentech data engineer interview, pipelines and SQL (went through the loop for a senior DE role)

de_derek · 6 replies

Did the Genentech DE loop a few months back. Most of what I read beforehand was generic or SWE-focused, so I'm writing the data engineer version.

Role: Senior Data Engineer, Research Informatics. South San Francisco, hybrid.

Process: Recruiter call -> HM call -> Technical screen (1 hour) -> Full loop (4 hours onsite or video for remote candidates)

Technical screen: This was the most immediately practical round. One SQL problem and one pipeline design discussion. The SQL was not trivial: multi-table join, window functions, handling missing values in a clinical dataset. They specifically asked about NULL handling in the context of patient data, which is a slightly different concern than regular analytics NULLs. Be thoughtful about what it means when a clinical measurement is missing vs. not measured vs. unknown.

Full loop: SQL and data modeling (60 min): Two problems. One schema design, one query optimization. They gave me a messy schema and asked how I'd redesign it for downstream BI use. Pipeline / architecture (45 min): They asked me to design an ELT pipeline for genomic sequencing data. Volume is large (think terabytes per batch), the transformation logic is complex, and the data is regulated. I talked about Airflow for orchestration, dbt for transformation, Snowflake or BigQuery for the warehouse, and spent a lot of time on data quality checks and logging. That last part felt important to them. Behavioral (45 min): Standard STAR questions but with a few domain twists, like "tell me about a time your pipeline produced incorrect results and how you caught and fixed it."

Tools they seemed to care about: Python, SQL, Airflow, dbt, at least familiarity with cloud storage (S3/GCS). They didn't seem to have a strong preference between Snowflake and BigQuery but asked me to compare them.

Comp (my offer, declined because of location): Base around 155k, 15% bonus target, RSUs around 45k/4yr. Reasonable but behind pure tech companies at the same level.

6 replies

analyst_ana

The NULL handling nuance for clinical data is a really good point I wouldn't have thought about. In standard analytics NULL usually just means missing/unknown but in clinical context the distinction between not collected, not applicable, and truly unknown has actual meaning.

ds_dmitri

How deep did they go on the dbt side? Like did they ask about models, tests, sources, or was it more surface-level?

de_derek

Medium depth. They asked about how I'd structure models (staging vs marts) and whether I use dbt tests and what kinds. I mentioned schema tests and custom generic tests for clinical data checks. They seemed satisfied. Didn't go into macros or advanced Jinja stuff.

finance_faye

The comp you shared is pretty close to what a friend got in a similar role last year. The RSU package is thinner than pure tech but Roche is a solid parent company from a stability standpoint. Different calculus.

infra_ines

Airflow is such a love-hate relationship at scale. Did they ask anything about failure handling and retries in Airflow specifically, or more general orchestration concepts?

de_derek

General concepts mostly: idempotency, backfill strategies, alerting on failures. I mentioned SLAs and DAG timeouts and that landed well. They're not running cutting-edge infrastructure so I don't think they're looking for deep Airflow internals.