🔒 Paid
Slow Query Regression
A recent deploy changed the shape of a hot query, and the planner has stopped using the index it used to rely on. A previously fast endpoint is now doing a full table scan on every call — CPU utilization is climbing, queries are queuing, and latency is spiking. Diagnose the plan regression and restore the correct index usage before the database falls over under load.
- Difficulty
- Senior
- Expected Time
- ~14 min
- Category
- Databases & Storage
Skills
- Diagnosing query plan regressions
- Index hints and planner statistics
- CPU contention under load
- Recognizing plausible-but-harmful mitigations
System Architecture
- API Service
- Query Planner
- Primary Database
- Statistics Collector
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