> For the complete documentation index, see [llms.txt](https://docs.rootcause.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rootcause.ai/more-details/applications/application-modules/ondataarrival.md).

# On data arrival

> Start a flow when a dataset is uploaded, synced, changed or its schema drifts.

Starts a flow when a dataset or connector this application watches receives data.

`topics` narrows which arrivals count — an upload, a connector sync, any change, or a schema drift. `debounceS` collapses a burst of arrivals into one run. Keeps state between runs so it knows what it has already seen, which makes it durable only.

## At a glance

|                          |                        |
| ------------------------ | ---------------------- |
| Module type              | `OnDataArrival`        |
| Category                 | Events                 |
| Default tier             | `durable`              |
| Runs on                  | `durable`              |
| Starts a flow            | yes                    |
| Holds a body             | no                     |
| Keeps state between runs | yes                    |
| Available in             | every application type |

## Parameters

### `concurrency`

`"replace" | "skip" | "queue"` · required · defaults to `"queue"`

What to do when the previous run is still going.

### `datasetIds`

`string[]` · required · defaults to `[]`

The datasets to watch.

### `connectorIds`

`string[]` · required · defaults to `[]`

The connectors to watch.

### `topics`

`("dataset.uploaded" | "dataset.synced" | "dataset.changed" | "dataset.schemaDrift")[]` · required · defaults to `["dataset.uploaded","dataset.synced"]`

Which kinds of arrival count: an upload, a sync, any change, a schema drift.

### `debounceS`

`number` · required · defaults to `0`

Collapse arrivals within this many seconds into one run.

## Inputs

*None.*

## Outputs

| Port        | Kind             | Connects to                        | Description                                |
| ----------- | ---------------- | ---------------------------------- | ------------------------------------------ |
| `event`     | `event`          | `event`, `json`                    | The event envelope: `{kind, at, payload}`. |
| `datasetId` | `scalar<string>` | `scalar`, `json`, `text`, `signal` | Which dataset arrived.                     |
| `data`      | `dataframe`      | `dataframe`, `signal`              | The rows that arrived, ready to work on.   |

***

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