MysqlHighPreparedStatementsUtilization(>80%) #

High utilization of prepared statements (>80%) on {{ $labels.instance }}

alert: MysqlHighPreparedStatementsUtilization(>80%)
annotations:
  description: |-
    High utilization of prepared statements (>80%) on {{ $labels.instance }}
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/mysqld-exporter/mysqlhighpreparedstatementsutilization(>80%)/
  summary: MySQL high prepared statements utilization (> 80%) (instance {{ $labels.instance
    }})
expr: max_over_time(mysql_global_status_prepared_stmt_count[1m]) / mysql_global_variables_max_prepared_stmt_count
  * 100 > 80
for: 2m
labels:
  severity: warning

Here is a sample runbook for the Prometheus alert rule:

Meaning #

The “MysqlHighPreparedStatementsUtilization” alert is triggered when the utilization of prepared statements in MySQL exceeds 80%. This means that the proportion of prepared statements in use compared to the maximum allowed has surpasssed the threshold, which may indicate a potential performance issue or resource bottleneck.

Impact #

A high prepared statements utilization can lead to:

• Increased memory usage and potential out-of-memory errors
• Decreased query performance and slower response times
• Increased risk of downtime and service unavailability
• Potential security risks if prepared statements are not properly sanitized

Diagnosis #

To diagnose the root cause of the high prepared statements utilization, follow these steps:

1. Check the MySQL error logs for any errors related to prepared statements or memory usage.
2. Verify the current configuration of the max_prepared_stmt_count variable to ensure it is set appropriately for the workload.
3. Analyze query performance using tools like the MySQL slow query log or a query analyzer to identify slow or inefficient queries that may be contributing to the high utilization.
4. Investigate recent changes to the workload or application code that may be causing an increase in prepared statement usage.

Mitigation #

To mitigate the high prepared statements utilization, follow these steps:

1. Increase the max_prepared_stmt_count variable to a higher value, but be cautious of potential memory usage increases.
2. Optimize queries to reduce the number of prepared statements in use, focusing on slow or inefficient queries identified during diagnosis.
3. Implement query caching to reduce the number of times prepared statements need to be executed.
4. Consider implementing connection pooling to reduce the number of connections and prepared statements in use.
5. Monitor the situation and adjust the mitigation strategies as needed to ensure the utilization remains below the threshold.