Refinery is a tail-based sampling proxy and operates at the level of an entire trace. Refinery examines whole traces and intelligently applies sampling decisions to each trace. These decisions determine whether to include or discard the trace data in the sampled data forwarded to Honeycomb.
A tail-based sampling model allows you to inspect an entire trace at one time and make a decision to sample based on its contents. For example, your data may have a root span that contains the HTTP status code to serve for a request, and another span that contains information on whether the data was served from a cache. Using Refinery, you can choose to keep only traces that had a 500 status code and were also served from a cache.
For more detailed information, please see Honeycomb's Refinery documentation.
Technical support for Refinery is available with Honeycomb's Enterprise plan.