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Capital One interview themes
What people report studying for — not a take-home dump. Last editorial update 2026-08-10.
ControlsPIICostIdempotency
Rounds you should expect
SQL + warehouse
MERGE with a late CDC event. Masking vs row access. Resource monitors.
Controls
Who can UNDROP prod. Why ACCOUNTADMIN is not a dashboard role.
Recently added questions
2026-08-10 · Fan-out revenue
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.