Sampling of performance data

Learn how BugSnag Performance uses sampling to gather data within your plan limits.

A popular app will generate enormous amounts of performance data. BugSnag Performance uses dynamic sampling to ensure that your users’ devices send the right amount of data for your plan.

Here’s how it works:

  • you choose a Performance plan, which buys you a certain number of spans per month across your organization
  • each day we allocate a portion of your organization’s quota to each of your projects that are using Performance Monitoring
  • based on a prediction of how much data your apps will generate that day, we assign a sampling probability to each project that will meet that project’s daily quota
  • the Performance SDKs use that sampling probability to decide which spans to send
  • the unit of sampling is the trace, so all the spans in a given trace will be sent

To check your usage over the last 30 days and compare it to your quota, go to “Span usage” in organization settings.

If our prediction leads to you sending more spans than are on your plan you will not be charged for the additional spans.

This sampling functionality for spans is completely different to the functionality that prevents you going over your Errors plan quota, which is why we renamed the Error functionality to “rate-limiting”.