Interview prep

Screens by company

The shape of rounds people discuss in public — marketplaces, banks, vendors, AI labs. Not a leaked question bank, and we do not scrape LinkedIn. Themes are updated from editorial review and a weekly public-signal job.

Recently added themes

2026-08-28 · Coinbase · sql
A deposit webhook retried. How do you not mint two ledger rows?
Idempotency key (or natural key on payment_id + event_type) and an upsert. A running-balance column you overwrite is not a ledger.
Public fintech interview-theme discussion (editorial)
2026-08-26 · Apple · system-design
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.
Public lakehouse interview-theme discussion (editorial)
2026-08-22 · LinkedIn · kafka
Your consumer group rebalances every few minutes during peak. What do you check first?
max.poll.interval.ms vs processing time, cooperative sticky assignment, and whether a slow partition (hot key) is triggering leave/join. Adding consumers without fixing poll interval often makes lag worse.
Public interview-theme discussion (editorial)
2026-08-18 · Snowflake · snowflake
A hiring manager asks you to put Cortex COMPLETE in a Looker explore. What do you say?
No. Materialize the label in ELT once, version the prompt, and let BI read a column. Dashboard refresh is a token bill and a non-deterministic metric.
SnowPro Specialty: Gen AI study themes + production practice
2026-08-10 · Capital One · sql
Revenue doubled after a “harmless” dimension join. How do you prove it in five minutes?
Row counts before and after the join, then GROUP BY the join key HAVING count(*) > 1 on the dimension. Fix the grain or aggregate the dim. Never DISTINCT the fact.
Publicly discussed bank-screen shape
2026-07-28 · Databricks · databricks
Someone ran VACUUM 0 HOURS on a gold table. What is actually broken?
In-flight readers and every snapshot older than now. VACUUM deletes files. OPTIMIZE does not. Restore is gone if the files are gone.
Vendor interview-theme writeups