# Keep the latest version of each item when merging scraper runs

**Use case:** 

Merges several runs of the same scraper and keeps one item per key, taken from the dataset you list last, so that the newest prices, stock or texts win. The kept item stays at its own position and an optional field shows how many duplicates each item had. Put the newest dataset last; only the order decides which version is kept.

## Input

```json
{
  "removeDuplicates": true,
  "keep": "last",
  "joinType": "left",
  "lookupPrefix": "lookup_",
  "keyNormalization": [
    "trim",
    "case",
    "width",
    "kana"
  ],
  "addSourceDataset": false,
  "addDuplicateCount": false
}
```

## Output

```json
{
  "sku": {
    "label": "Sku"
  },
  "name": {
    "label": "Name"
  },
  "maker": {
    "label": "Maker"
  },
  "price": {
    "label": "Price"
  },
  "currency": {
    "label": "Currency"
  },
  "url": {
    "label": "Url"
  },
  "maker_country": {
    "label": "Maker country"
  },
  "maker_supportEmail": {
    "label": "Maker support email"
  },
  "maker_leadTimeDays": {
    "label": "Maker lead time days"
  },
  "_sourceDataset": {
    "label": "Source dataset"
  },
  "_duplicateCount": {
    "label": "Duplicate count"
  }
}
```

## How it works

### 1. Sign up on Apify or log in

The Merge, Deduplicate & Join Datasets Actor is ready to run with the inputs already set for "Keep the latest version of each item when merging scraper runs". [Sign up or log in](https://console.apify.com/create-task-from-example/jh2gp8aGIKaWeaWa8) and you'll land in Apify Console with a copy of this exact task.

### 2. Start the "Keep the latest version of each item when merging scraper runs" task

The Merge, Deduplicate & Join Datasets Actor will start running based on the input automatically. You can also change all the input fields, like remove duplicates, which duplicate to keep, and more, to match your specific use case.

### 3. Receive the "Keep the latest version of each item when merging scraper runs" output

Monitor the progress in real time. You will be notified as soon as your dataset is complete and ready for review. Each result includes data such as sku, name, maker, and more.

### 4. Integrate into your workflow

The final output is delivered in JSON, CSV, or Excel format, ready to be plugged into your workflow. You can also [run the "Keep the latest version of each item when merging scraper runs" task via API](https://apify.com/quietworkslab/merge-dedup-datasets.md).

## FAQ

### How does the latest-version task know which item is newest?

The latest-version task does not read dates: it keeps the item from the dataset read last. List your datasets from oldest to newest, so the newest dataset is read last.

### Is every item read twice with keep last?

Yes. With keep last, the latest-version task first counts every key and then writes the items, but each item is charged only once. The maximum cost per run must cover all items, or the run stops before reading them.

### How much does merging datasets cost?

The Merge, Deduplicate & Join Datasets Actor charges $0.0001 per item read ($0.10 per 1,000 items) and one item per started 20 items of a lookup dataset, plus Apify's Actor start event. The built-in sample is not charged per item.

## About this Actor

This example demonstrates how to use [Merge, Deduplicate & Join Datasets](https://apify.com/quietworkslab/merge-dedup-datasets.md) with a specific input configuration. Visit the [Actor detail page](https://apify.com/quietworkslab/merge-dedup-datasets.md) to learn more, explore other use cases, and run it yourself.


## How to integrate an Actor?

This Task's input is already configured above. Use it as-is rather than inventing a new one.

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 full API examples (JavaScript, Python, CLI, MCP, OpenAPI), see this Task's Actor page: https://apify.com/quietworkslab/merge-dedup-datasets.md

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`).