# Merge & Deduplicate Datasets - Reliable, Any Size (`geese_chief/dataset-merge-dedup`) Actor

Merge any number of Apify datasets into one and remove duplicates by the fields you choose (url, id, email...). Keep unique items or only the duplicates, pick output fields, tag each item with its source. Streams data, so millions of items work. Pick datasets from your storage: no permission errors.

- **URL**: https://apify.com/geese_chief/dataset-merge-dedup.md
- **Developed by:** [Ponytail Data](https://apify.com/geese_chief) (community)
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $0.35 / 1,000 output items

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.
Since this Actor supports Apify Store discounts, the price gets lower the higher subscription plan you have.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

An Actor is a serverless cloud program that runs on the Apify platform. It has two run modes.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.

Apify vocabulary and the platform model are defined once, in the agent quickstart at https://apify.com/agents.md.

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For examples already wired to this Actor's own input schema, see the [API](#api) section below.

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).

# README

## Merge & Deduplicate Datasets - Reliable, Any Size

Merge **any number of Apify datasets** into one clean dataset and **remove duplicates** by the fields you choose. Use it to combine runs from several scrapers, tidy up a scheduled scraper's history, or find the items that appear in more than one dataset.

- **Pick datasets straight from your storage.** Input uses Apify's dataset picker, so the run gets read access to exactly the datasets you choose. No "insufficient permissions" failures.
- **Dedup by any fields**: `url`, `email`, `productId` + `variant`... or by whole item.
- **Three outputs**: unique items (first occurrence wins, original order kept), only the duplicates, or just the counts.
- **Trim output**: keep only the fields you need, and tag every item with its `_sourceDataset`.
- **Streams data**, so millions of items work in small memory. A `STATS` record shows items loaded, unique, duplicates and output.

### Example

Dataset A has products 1–7 and dataset B has products 5–10. Deduplicating by `url` gives products 1–10, 10 unique items, with 3 duplicates removed.

```json
{
  "datasetIds": ["5HVQsVrFp3bTQ06Yv", "xbRTmeYjFNWdbMs8e"],
  "dedupFields": ["url"],
  "output": "unique",
  "outputFields": [],
  "addSourceDataset": true
}
```

`STATS` record:

```json
{"datasets": 2, "itemsLoaded": 13, "uniqueItems": 10, "duplicateItems": 3, "itemsOutput": 10}
```

Leave `datasetIds` empty to try it on built-in demo data.

### Use cases

- **Combine scraper runs**: merge the datasets of many scheduled runs into one deduplicated list.
- **Incremental scraping**: find what's new compared with yesterday (output only the unique items of today's dataset after yesterday's).
- **Lead lists**: merge lead sources and drop repeated emails or domains.
- **Data quality checks**: count duplicates without outputting anything.

### Pricing

**$0.50 per 1,000 output items** ($0.0005 per item). Counting duplicates with output "Nothing" only costs the start fee.

### FAQ

**Which dataset is kept when items are duplicated?** The first one, in the order you list the datasets.

**Can I use datasets from other accounts?** Only datasets your account can read.

**Nested fields?** Use top-level field names. Whole-item deduplication compares everything, including nested values.

# Actor input Schema

## `datasetIds` (type: `array`):

Datasets to merge, in order. Pick them from your storage (or paste IDs). Leave empty to try the Actor on demo data.

## `dedupFields` (type: `array`):

Items with the same values in these fields are duplicates (e.g. url, or productId + variant). Leave empty to remove only fully identical items. Nested fields are not supported: use top-level field names.

## `output` (type: `string`):

What to save to the output dataset. Counts are always saved to the STATS record.

## `outputFields` (type: `array`):

Only keep these fields in the output. Leave empty to keep whole items.

## `addSourceDataset` (type: `boolean`):

Add a \_sourceDataset field with the ID of the dataset each item came from.

## Actor input object example

```json
{
  "output": "unique",
  "addSourceDataset": false
}
```

# Actor output Schema

## `results` (type: `string`):

No description

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {};

// Run the Actor and wait for it to finish
const run = await client.actor("geese_chief/dataset-merge-dedup").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {}

# Run the Actor and wait for it to finish
run = client.actor("geese_chief/dataset-merge-dedup").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{}' |
apify call geese_chief/dataset-merge-dedup --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,geese_chief/dataset-merge-dedup"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/MPHOTySdMH70cKqzP/builds/wvaKp9DVZ65Fo557A/openapi.json