Metric Grouping Issues are most commonly discovered when a metric limit is exceeded and a ‘clamp’ is triggered.
When the count of unique metric names reporting to an application or account surpasses a set limit, a metric clamp is triggered. This prevents any new metrics from reporting:
Application ‘Whitelist’ - Limit default of 300K.
This is called a ‘whitelist’ because the metrics names which have so far reported to the application, up to the limit, are whitelisted. Any new metric names cannot be created until the clamp is lifted.
When the whitelist clamp is triggered, a support ticket is opened up in the account owner’s name and the admins are CC’d. When you engage in the ticket, New Relic Support can help in addressing the metric grouping issue and removing the whitelist clamp.