kb/db_connection_pool.md

# Database Connection Pool Exhaustion

## Symptoms
- `too many connections`, `connection refused`, or pool timeout errors
- Spikes in DB connections and wait time
- Slow queries or lock contention observed

## Checks
- Inspect application pool size vs database max connections
- Review slow queries and transaction lengths
- Check connection leak metrics and proper closing
- Validate DB host/port/DNS and TLS settings
- Examine recent traffic/load changes

## Fix
- Tune pool size and DB max connections
- Fix connection leaks and ensure pooling is enabled
- Optimize slow queries; add indexes where needed
- Scale database or replicas to handle load