# Dataset Class

**Added in:** `@mastra/core@1.4.0`

The `Dataset` class provides methods for item CRUD, versioning, and experiment management on a single dataset. Obtained via `mastra.datasets.get()` or `mastra.datasets.create()`.

## Usage examples

### Add items and run an experiment

```typescript
import { Mastra } from "@mastra/core";

const mastra = new Mastra({ /* storage config */ });

const dataset = await mastra.datasets.create({
  name: "QA pairs",
});

// Add items
await dataset.addItems({
  items: [
    { input: { question: "What is AI?" }, groundTruth: { answer: "Artificial Intelligence" } },
    { input: { question: "What is ML?" }, groundTruth: { answer: "Machine Learning" } },
  ],
});

// Run an experiment
const summary = await dataset.startExperiment({
  targetType: "agent",
  targetId: "my-agent",
  scorers: ["accuracy"],
});

console.log(`${summary.succeededCount}/${summary.totalItems} succeeded`);
```

### Manage versions and history

```typescript
import { Mastra } from "@mastra/core";

const mastra = new Mastra({ /* storage config */ });

const dataset = await mastra.datasets.get({ id: "dataset-id" });

// List versions
const { versions } = await dataset.listVersions();

// List items at a specific version
const items = await dataset.listItems({ version: 2 });

// Get item change history
const history = await dataset.getItemHistory({ itemId: "item-id" });
```

## Access

`Dataset` is not instantiated directly. Obtain one via `DatasetsManager`:

```typescript
const dataset = await mastra.datasets.get({ id: "dataset-id" });
// or
const dataset = await mastra.datasets.create({ name: "My dataset" });
```

## Properties

For the full dataset record (name, description, schemas, version, timestamps), call [`dataset.getDetails()`](https://mastra.ai/reference/datasets/getDetails).

**id:** (`string`): The unique identifier of the dataset. Read-only.

## Related

- [DatasetsManager class](https://mastra.ai/reference/datasets/datasets-manager)
- [dataset.startExperiment()](https://mastra.ai/reference/datasets/startExperiment)
- [dataset.addItems()](https://mastra.ai/reference/datasets/addItems)
- [dataset.listVersions()](https://mastra.ai/reference/datasets/listVersions)