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# Datasets and batches in Mammoth: Combine or Replace

> What a Mammoth dataset is, how each load of new data becomes a batch, and when to use the Combine or Replace update method on new data.

A dataset is your data imported into a Mammoth project, and each load of data into it is a batch. The dataset's **Update Method** decides whether new data is added beside the old (Combine) or replaces it (Replace). For how datasets fit with views and pipelines, see [Core ideas](https://mammoth.io/docs/learn/start/core-ideas/).

## Dataset: your imported data

A **Dataset** is your data, imported into Mammoth. A CSV upload, database query or API response all become datasets with columns and types, a source, and one or more batches, and you work on them the same way. Mammoth reads column types on import; change one later with a Convert Column Type task.

Click **New dataset** in the Data Library to create one by file upload, paste, a connector, a URL, a webhook, a sample file, or by generating data with AI ([Choose how to bring data in](https://mammoth.io/docs/learn/get-data-in/)). You can then add or replace its data, combine it with other datasets, open it in views, and export the results.

![New Dataset dialog on the Generate with AI option, with a generated manufacturing sensor table and Create new dataset button](https://mammoth.io/docs/images/20260408_154753_dataset_creaiton.webp)

## Batch: each load of new data

Each time data is added to a dataset, Mammoth records it as a **Batch**. The dataset's panel lists its batches, each with its source, row count and state (**Active**, **Suspended** or **Pending Delete**). The Activity Log records batch changes.

### Combine or Replace new data

A dataset's **Update Method** decides what happens to new data:

| Update Method | What happens | Use it for |
| --- | --- | --- |
| Combine | The new data becomes another batch beside the existing ones, and the dataset grows. | History that builds up over time, such as monthly sales or daily transactions |
| Replace | The previous batches are deleted and the new data becomes the only batch. | Reports that need only the latest data, such as a daily inventory snapshot |

Monthly files in Combine mode give one batch per month; a table fully reloaded with Replace always has one batch. You can also **Suspend** a batch, which leaves it out of every view without deleting it, or **Delete** it, which can't be undone. See [Batches: see and fix what arrived](https://mammoth.io/docs/learn/get-data-in/batches/).

![Dataset panel for Multi-Store_Retail_Sales.csv with a Batches table listing three active batches of 51 rows each](https://mammoth.io/docs/images/20260408_155041_Batch_combine.webp)

## Related

- [Views, pipelines and tasks](https://mammoth.io/docs/learn/start/views-pipelines-and-tasks/): where you work on a dataset.
- [Add or replace data](https://mammoth.io/docs/learn/get-data-in/add-or-replace-data/): load new data into an existing dataset.
- [Workspaces and projects](https://mammoth.io/docs/learn/start/workspaces-and-projects/): where datasets live and who sees them.

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Source: https://mammoth.io/docs/learn/start/datasets-and-batches.md · Updated: 2026-11-08