# DB Pool Exhaustion Runbook

## Symptoms
- PostgreSQL connection pool at 20/20 active connections
- Lock contention detected on auth-db
- Cascading latency on auth-service and api-gateway

## Diagnostic Steps
1. Query pool metric on auth-db to confirm exhaustion
2. Check lock_contention flag in pool status
3. Inspect auth-db logs for long-running query signatures

## Remediation Options
Option A — kill long-running queries:
  - remediation: kill_pid on auth-db
  - Verify pool utilisation drops below 80%

Option B — release connections:
  - remediation: update_config on auth-db with max_connections=40
  - Verify lock_contention clears

Option C — scale upstream:
  - remediation: scale_up on auth-service to reduce connection pressure

## Key Metric
Pool utilisation must drop below 50% for full remediation credit.
Lock contention must clear before submitting resolution.