# Diff Datasets (`pocesar/diff-datasets`) Actor

Take one dataset on Apify platform, compare it to another, and output the missing ones.
This can also be used to output only changed items, using a compound key

- **URL**: https://apify.com/pocesar/diff-datasets.md
- **Developed by:** [Paulo Cesar](https://apify.com/pocesar) (community)
- **Categories:** Automation, Open source
- **Stats:** 18 total users, 0 monthly users, 0.0% runs succeeded, 4 bookmarks
- **User rating**: No ratings yet

## Pricing

Pay per usage

This Actor is paid per platform usage. The Actor is free to use, and you only pay for the Apify platform usage, which gets cheaper the higher subscription plan you have.

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

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
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.
Actors are written with capital "A".

## 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.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## Diff datasets

Take one dataset on Apify platform, compare to another, and output the missing ones.
This can also be used to output only changed items, using a compound key.

Supports using whole nested objects as value, they are `JSON.stringify`'d before being turned
into a small non-cryptographic space efficient hash

### Example

```js
await Apify.call('pocesar/diff-datasets', {
    baseDatasetId: 'LdNAlaOY1aKGhwAah', // place the datasets here. The order of "base" and "other" matters
    otherDatasetId: 'Bzu1pgOjenN43VhPY', // existing items in "base" are not output from "other"
    uniqueFields: [
        // simple primitive field value, like string, number, boolean
        "pageUrl",

        // you can use lodash.get notation to get nested items,
        // in this case `sub.fields.0` works like `sub.fields[0]` and the object looks like
        // {
        //    pageUrl: "https//pageurl",
        //    sub: {
        //      fields: [
        //        {...},
        //        {...}
        //      ]
        //    }
        //  }
        "sub.fields.0",

        // you can also use .length to count arrays or string characters, as in
        "sub.fields.length",
        "pageUrl.length"
    ],
});
```

### Limitations

- Every value is kept in memory while reading from the `base` dataset, more items more memory needed.
- The key value store might choke when trying to save the in-memory `Set` with too many items

### License

Apache 2.0

# Actor input Schema

## `baseDatasetId` (type: `string`):

This dataset ID that will serve as base and collect the unique items.

## `otherDatasetId` (type: `string`):

Only non-existing items from base will be ouput using this other dataset

## `uniqueFields` (type: `array`):

Unique fields to create a compound key. For example, an unique ID field might not be unique, so you place two fields that make the item itself unique

## `maxBufferSize` (type: `integer`):

How many items to buffer in memory before outputting it

## Actor input object example

```json
{
  "uniqueFields": [
    "id",
    "size",
    "array.0",
    "array.length",
    "string.length"
  ],
  "maxBufferSize": 20000
}
```

# 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("pocesar/diff-datasets").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("pocesar/diff-datasets").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print("💾 Check your data here: https://console.apify.com/storage/datasets/" + run["defaultDatasetId"])
for item in client.dataset(run["defaultDatasetId"]).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 pocesar/diff-datasets --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "command": "npx",
            "args": [
                "mcp-remote",
                "https://mcp.apify.com/?tools=pocesar/diff-datasets",
                "--header",
                "Authorization: Bearer <YOUR_API_TOKEN>"
            ]
        }
    }
}

```

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/dgSyB9H3E9b5I8FQu/builds/JIlJRETrpgDtyTShO/openapi.json