Sampling is a process that restricts the amount of traces that are generated by a system. The exact sampler you should use depends on your specific needs, but in general you should make a decision at the start of a trace, and allow the sampling decision to propagate to other services.

A sampler needs to be set on the tracer provider when its configured, as follows:

provider := sdktrace.NewTracerProvider(

AlwaysSample and NeverSample are fairly self-explanatory. Always means that every trace will be sampled, the converse holds as true for Never. When you’re getting started, or in a development environment, you’ll almost always want to use AlwaysSample.

Other samplers include:

  • TraceIDRatioBased, which will sample a fraction of traces, based on the fraction given to the sampler. Thus, if you set this to .5, half of traces will be sampled.
  • ParentBased, which behaves differently based on the incoming sampling decision. In general, this will sample spans that have parents that were sampled, and will not sample spans whose parents were not sampled.

When you’re in production, you should consider using the TraceIDRatioBased sampler with the ParentBased sampler.