> 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/distinct.md).

# Distinct

> Drop duplicate rows, over all or the named columns.

Drops duplicate rows, comparing `columns` when it is non-empty and every column otherwise. Which row of a duplicate set survives is not defined — the engine partitions without an order — so do not rely on it when the other columns differ.

## At a glance

|                          |                        |
| ------------------------ | ---------------------- |
| Module type              | `Distinct`             |
| Category                 | Primitives · Dataframe |
| Default tier             | `reactive`             |
| Runs on                  | `reactive`, `durable`  |
| Starts a flow            | no                     |
| Holds a body             | no                     |
| Keeps state between runs | no                     |
| Available in             | every application type |

## Parameters

### `columns`

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

The columns compared. Empty compares every column.

## Inputs

| Port   | Kind        | Required | Description                                                                                                                           |
| ------ | ----------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------- |
| `on`   | `event`     | no       | Implicit on every module that does not itself start a flow: wire an event here to make this module the start of what that event runs. |
| `data` | `dataframe` | yes      | The frame to work on.                                                                                                                 |

## Outputs

| Port     | Kind        | Connects to           | Description               |
| -------- | ----------- | --------------------- | ------------------------- |
| `output` | `dataframe` | `dataframe`, `signal` | One row per distinct key. |

***

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