Hardware / privacy
Apple interview themes
What people report studying for — not a take-home dump. Last editorial update 2026-08-08.
Rounds you should expect
Design
Two engines, one Iceberg table. What you refuse to dual-write. How identifiers stay out of a vendor LLM.
SQL
Grain and uniqueness under a privacy constraint — no “just dump the fact to a notebook.”
Recently added questions
2026-08-26 · Shared lake, one writer
Two engines must share one lake table. What do you refuse to do?
Dual-write CSV or two independent Delta copies. Pick Iceberg (or UniForm) with a single writer. Two writers is how the copies lie.
2026-09-02 · Federated OLTP scans
A 09:00 dashboard federates Iceberg facts to prod Postgres dims. What do you refuse?
Scanning the primary for BI. Replicate dims to the lake. Federation is a small lookup, not the exec pack.
From the question bank
easy · Warehouse · Databricks
When do you pick Delta on Databricks versus Iceberg on a shared lake?
Practice →easy · Warehouse · Databricks
UniForm vs dual-write Delta and Iceberg.
Practice →medium · Warehouse · Databricks
You VACUUMed with a 7-day retention and a reader is on an 8-day-old notebook. What happens?
Practice →medium · Coding · Spark
Driver vs executor. Where does your Python UDF actually run?
Practice →easy · Coding · Spark
foreach on the driver vs foreachPartition.
Practice →hard · Coding · Spark
AQE is on. You still got a 2 TB shuffle. What did AQE not fix?
Practice →medium · Coding · Spark
repartition(200) before a write. When is that the wrong knob?
Practice →hard · Data modeling · Python & modeling
You hashed emails as a join key. Legal says stop. What was the modeling mistake?
Practice →hard · System design · System design
Two engines must share one lake table. What do you refuse to do?
Practice →hard · System design · System design
Multi-region: EU data cannot leave EU, US analysts want a global dashboard. Draw the legal design.
Practice →medium · System design · System design
PII in bronze, marketing wants a campaign table with emails. Controls you actually draw.
Practice →medium · Streaming · Apache Flink
Checkpoint vs savepoint.
Practice →