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A dataset pipeline transforms spans or traces from your project logs into dataset rows in bulk. It automates the same flow as promoting individual traces from logs, but applies it to many spans or traces at once and keeps the logic in version-controlled code. You define a pipeline with DatasetPipeline(...) in a TypeScript or Python file, then run it with the bt datasets pipeline CLI command.
Beta — This feature is subject to change.
Dataset pipelines require bt CLI v0.10.0 or later, plus the braintrust SDK for the language you write the pipeline in: TypeScript SDK v3.16.0 or later, or Python SDK v0.23.0 or later.

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Define a pipeline

A pipeline definition has three parts:
  • source: Which project to read from, an optional SQL filter, and whether to operate on individual spans or entire traces (scope).
  • transform: A function that receives a source span or trace and returns one or more dataset rows, or nothing to skip it.
  • target: The dataset to write to. Braintrust creates the dataset if it does not exist.
pipeline.ts
import { DatasetPipeline } from "braintrust";

DatasetPipeline({
  name: "support-cases", // Optional; required only when a file defines multiple pipelines
  source: {
    projectName: "Customer Support", // Replace with your source project
    filter: "metadata.flagged = true", // Optional SQL filter; omit to consider all spans
    scope: "span", // "span" (default) or "trace"
  },
  transform: ({ id, input, output, expected, metadata, trace }) => {
    return {
      input,
      expected: output, // Map the production output to the expected value
      metadata,
    };
  },
  target: {
    projectName: "Customer Support", // Replace with your target project
    datasetName: "Support cases", // Created if it does not exist
  },
});
The transform function returns a single row, a list of rows, or null/None to skip the source. A row accepts the standard dataset fields: input, expected, metadata, tags, and id. When you omit id, the row inherits the source span or trace ID. When scope is "span", the transform receives the span’s id, input, output, expected, and metadata, along with the full trace. When scope is "trace", it receives only the trace.

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Run a pipeline

Run the full pipeline in one shot. The --limit flag controls how many source spans or traces to discover, and --window sets how far back to look, which defaults to the last day (1d). For the full list of flags, see the bt datasets pipeline CLI reference. 
bt datasets pipeline run ./pipeline.ts --limit 100 --window 30d
run discovers source refs, transforms them, and inserts the resulting rows into the target dataset.

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Staged workflow

For larger jobs, or when you want to inspect or edit rows before writing them, split the run into three stages: 
# 1. Discover source refs and write them to pulled.jsonl
bt datasets pipeline pull ./pipeline.ts --limit 500

# 2. Apply the transform and write the results to transformed.jsonl
bt datasets pipeline transform ./pipeline.ts

# 3. Push the transformed rows to the target dataset
bt datasets pipeline push ./pipeline.ts
Each stage writes its artifacts to bt-sync/ by default: pull writes pulled.jsonl and transform writes transformed.jsonl. You can inspect or edit transformed.jsonl before running push. Use --root to change the directory, or --out and --in to override individual artifact paths. For the full set of flags, including source and target overrides and concurrency controls, see the bt datasets pipeline CLI reference.

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Next steps