Optimize a slow SQL query on a large fact table
EXPLAIN, indexes, selective columns, partitioning, avoid N+1.
Why this matters
Asked by 34% of candidates. Common screening signal before deeper system design and production follow-up rounds.
Frequently followed by
Interview focus
Why
Asked by 34% of candidates. Common screening signal before deeper system design and production follow-up rounds.
Follow-ups
What changes if the table grows 10x next quarter, Practical database performance and explain-plan literacy, Adding indexes blindly without cardinality or write-amplification trade...
Evaluates
Technical depth, Trade-off thinking, Communication, Production awareness