PostgresqlNotEnoughConnections #

PostgreSQL instance should have more connections (> 5)

alert: PostgresqlNotEnoughConnections
annotations:
  description: |-
    PostgreSQL instance should have more connections (> 5)
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/postgres-exporter/postgresqlnotenoughconnections/
  summary: Postgresql not enough connections (instance {{ $labels.instance }})
expr: sum by (datname) (pg_stat_activity_count{datname!~"template.*|postgres"}) <
  5
for: 2m
labels:
  severity: warning

Here is the runbook for the Prometheus alert rule PostgresqlNotEnoughConnections:

Meaning #

The PostgresqlNotEnoughConnections alert is triggered when the total number of connections to a PostgreSQL instance falls below 5. This alert is raised to prevent potential issues with the database performance and availability.

Impact #

If this alert is not addressed, it may lead to:

• Degraded database performance
• Increased latency
• Errors or failures in applications relying on the database
• Potential data loss or corruption

Diagnosis #

To diagnose the issue, follow these steps:

1. Check the PostgreSQL instance’s connection count using the pg_stat_activity metric.
2. Verify that the instance is not experiencing any other issues, such as high CPU usage or disk space issues.
3. Review the database configuration and connection settings to ensure they are adequate for the workload.
4. Investigate recent changes to the database or application configuration that may have caused the connection count to drop.

Mitigation #

To mitigate the issue, follow these steps:

1. Increase the maximum number of connections allowed in the PostgreSQL configuration file (e.g., postgresql.conf).
2. Review and optimize database queries to reduce the load on the instance.
3. Consider load balancing or horizontal scaling to distribute the workload across multiple instances.
4. Implement connection pooling or other optimization techniques to improve database performance.
5. Monitor the instance’s connection count and adjust as necessary to prevent future occurrences of this alert.