---
title: "Datasets"
description: "Create and inspect datasets with @arizeai/phoenix-client"
---

Datasets are the foundation for experiment runs. The dataset helpers cover creation (which upserts by name), record inspection, and example appends.

<section className="hidden" data-agent-context="relevant-source-files" aria-label="Relevant source files">
  <h2>Relevant Source Files</h2>
  <ul>
    <li>
      <code>src/datasets/createDataset.ts</code> for the exact return shape and
      upsert-by-name behavior
    </li>
  </ul>
</section>

## Create A Dataset

```ts
import { createDataset } from "@arizeai/phoenix-client/datasets";

const { datasetId } = await createDataset({
  name: "support-eval",
  description: "Support questions with expected answers",
  examples: [
    {
      input: { question: "Where is my order?" },
      output: { answer: "Use the tracking page in your account." },
      metadata: { channel: "chat" },
    },
  ],
});
```

## Upsert Or Append

`createDataset()` upserts by name: re-running it with the same name updates the existing dataset to match the examples you pass, and an unchanged upload is a no-op. To keep existing examples and add more, use `appendDatasetExamples()` instead of re-running `createDataset()` with the extra examples.

```ts
import {
  appendDatasetExamples,
  createDataset,
} from "@arizeai/phoenix-client/datasets";

const dataset = await createDataset({
  name: "support-eval",
  description: "Support questions with expected answers",
  examples: [
    {
      input: { question: "Where is my order?" },
      output: { answer: "Use the tracking page in your account." },
    },
  ],
});

await appendDatasetExamples({
  dataset,
  examples: [
    {
      input: { question: "How do I reset my password?" },
      output: { answer: "Use the forgot password flow." },
    },
  ],
});
```

`createDataset()` returns `{ datasetId }`, so you can pass that object directly as the dataset selector for append or experiment calls.

## Read Back Dataset State

Use `getDataset`, `getDatasetExamples`, and `getDatasetInfo` to inspect datasets after creation.

<section className="hidden" data-agent-context="source-map" aria-label="Source map">
  <h2>Source Map</h2>
  <ul>
    <li><code>src/datasets/createDataset.ts</code></li>
    <li><code>src/datasets/appendDatasetExamples.ts</code></li>
    <li><code>src/datasets/getDataset.ts</code></li>
    <li><code>src/datasets/getDatasetExamples.ts</code></li>
    <li><code>src/datasets/getDatasetInfo.ts</code></li>
  </ul>
</section>