Set a sampling rate for traces

This section is relevant for those using the LangSmith SDK or LangChain, not for those logging directly with the LangSmith API.

By default, all traces are logged to LangSmith. To down-sample the number of traces logged to LangSmith, set the LANGSMITH_TRACING_SAMPLING_RATE environment variable to any float between 0 (no traces) and 1 (all traces). For instance, setting the following environment variable will log 75% of the traces.

export LANGSMITH_TRACING_SAMPLING_RATE=0.75

This works for the traceable decorator and RunTree objects.