PostgresqlCommitRateLow #

Postgresql seems to be processing very few transactions

alert: PostgresqlCommitRateLow
annotations:
  description: |-
    Postgresql seems to be processing very few transactions
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/postgres-exporter/postgresqlcommitratelow/
  summary: Postgresql commit rate low (instance {{ $labels.instance }})
expr: rate(pg_stat_database_xact_commit{datname !~ 'template.|postgres'}[1m]) < 10
for: 2m
labels:
  severity: critical

Here is a runbook for the Prometheus alert rule PostgresqlCommitRateLow:

Meaning #

The PostgresqlCommitRateLow alert is triggered when the rate of committed transactions in a PostgreSQL database falls below 10 per minute. This could indicate a problem with the database, the application, or the infrastructure that prevents transactions from being committed successfully.

Impact #

A low commit rate can have significant consequences on the application and the business. Some possible impacts include:

• Delayed or lost transactions, leading to data inconsistencies and errors
• Reduced system performance, leading to user frustration and decreased productivity
• Increased latency, leading to timeouts and failures
• Decreased system availability, leading to revenue loss and reputational damage

Diagnosis #

To diagnose the root cause of the low commit rate, follow these steps:

1. Check the PostgreSQL logs: Review the PostgreSQL logs to identify any errors or warnings related to transaction processing.
2. Verify database connections: Check the number of active connections to the database and verify that they are within expected limits.
3. Investigate transaction latency: Analyze the latency of transactions using tools like pg_stat_activity or external monitoring tools.
4. Check disk space and I/O: Verify that the disk space and I/O resources are sufficient to handle the transaction load.
5. Review application logs: Check the application logs to identify any errors or issues that may be related to transaction processing.

Mitigation #

To mitigate the effects of a low commit rate, follow these steps:

1. Investigate and resolve underlying issues: Address the root cause of the low commit rate, as identified during diagnosis.
2. Increase database resources: Temporarily increase the database resources (e.g., connections, CPU, memory) to handle the transaction load.
3. Optimize database configuration: Review and optimize database configuration settings, such as max_connections and shared_buffers, to improve performance.
4. Implement transaction retry mechanisms: Implement retry mechanisms in the application to handle temporary failures and reduce the impact of lost transactions.
5. Notify stakeholders: Inform stakeholders of the issue and provide regular updates on the mitigation efforts and expected resolution time.