Migrate large Hugging Face datasets to MongoDB with a looping subworkflow

This n8n template provides a production-ready, memory-safe pipeline for ingesting large Hugging Face datasets into MongoDB using batch pagination.
It is designed as a reusable data ingestion layer for RAG systems, recommendation engines, analytics pipelines, and ML workflows.

The template includes:

• A main workflow that orchestrates pagination and looping
• A subworkflow that fetches dataset rows, sanitizes them, and inserts them into MongoDB safely

🚀 What This Template Does

• Fetches rows from a Hugging Face dataset using the datasets-server API
• Processes data in configurable batches (offset + length)
• Removes Hugging Face _id fields to avoid MongoDB duplicate key errors
• Inserts clean documents into MongoDB
• Automatically loops until all dataset rows are ingested
• Handles large datasets without memory overflow

🧩 Architecture Overview

Main Workflow (Orchestrator)

• Starts the ingestion process
• Defines dataset, batch size, and MongoDB collection
• Repeatedly calls the subworkflow until no rows remain

Subworkflow (Batch Processor)

• Fetches a single batch of rows from Hugging Face
• Splits rows into individual items
• Removes _id fields
• Inserts documents into MongoDB
• Returns batch statistics to the main workflow

🔁 Workflow Logic (High-Level)

1. Set initial configuration:
   • Dataset name
   • Split (train, test, etc.)
   • Batch size
   • Offset
2. Fetch rows from Hugging Face
3. If rows exist:
   • Split rows into items
   • Remove _id
   • Insert into MongoDB
4. Increase offset
5. Repeat until no rows are returned

📦 Default Configuration

All values can be changed easily from the Config_Start node.

🛠 Prerequisites

• n8n (self-hosted or cloud)
• MongoDB (local or hosted)
• MongoDB credentials configured in n8n
• Internet access to datasets-server.huggingface.co

▶️ How to Use

1. Import the workflow JSON into n8n
2. Configure MongoDB credentials in the MongoDB node
3. Update dataset parameters if needed:
   • Dataset name
   • Split
   • Batch size
   • Collection name
4. Run the workflow using the Manual Trigger
5. Monitor execution until completion

🧠 Why _id Is Removed

Hugging Face dataset rows often include an _id field.
MongoDB requires _id values to be unique, so reusing these values can cause insertion failures.

This template:

• Removes the Hugging Face _id
• Lets MongoDB generate its own ObjectId
• Prevents duplicate key errors
• Allows safe re-runs and incremental ingestion

🔍 Ideal Use Cases

✅ RAG (Retrieval-Augmented Generation)

• Store dataset content as source documents
• Add embeddings later using OpenAI, Mistral, or local models
• Connect MongoDB to a vector database or hybrid search

✅ Recommendation Systems

• Build item catalogs from public datasets
• Use embeddings or metadata for similarity search
• Combine with user behavior data downstream

✅ ML & Analytics Pipelines

• Centralize dataset ingestion
• Normalize data before training or analysis

⚙️ Recommended Enhancements

You can easily extend this template with:

• Upsert logic using a deterministic hash (idempotent ingestion)
• Embedding generation before or after insertion
• Schema validation or field filtering
• Rate-limit handling & backoff
• Parallel ingestion for faster processing

⚠️ Notes & Best Practices

• Reduce batch size if you encounter memory limits
• Verify dataset license before production use
• Add indexes in MongoDB for faster downstream querying
• Use upserts if you plan to re-run ingestion frequently

📄 License & Disclaimer

This workflow template is provided as-is.
You are responsible for:

• Dataset licensing compliance
• Infrastructure costs
• Downstream data usage

Hugging Face datasets are subject to their respective licenses.

⭐ Template Summary

Category: Data Ingestion
Complexity: Intermediate
Scalability: High
Memory Safe: Yes
Production Ready: Yes

If you want a version with:

• Upserts instead of inserts
• Built-in embeddings
• Vector database support
• Logging & monitoring

Just say the word and I’ll generate the enhanced workflow JSON.