How to Move Data from MongoDB to PostgreSQL: Easy Steps & Methods

When it comes to migrating data from MongoDB to PostgreSQL, I’ve had my fair share of trying different methods and even making rookie mistakes, only to learn from them. The migration process can be relatively smooth if you have the right approach, and in this blog, I’m excited to share my tried-and-true methods with you to move your data from MongoDB to PostgreSQL. 

In this blog, I’ll walk you through three easy methods: two automated methods for a faster and simpler approach and one manual method for more granular control. Choose the one that works for you. Let’s begin!

What is MongoDB?

MongoDB is a modern, document-oriented NoSQL database designed to handle large amounts of rapidly changing, semi-structured data. Unlike traditional relational databases that store data in rigid tables, MongoDB uses flexible JSON-like documents with dynamic schemas, making it an ideal choice for agile development teams building highly scalable and available internet applications.

At its core, MongoDB features a distributed, horizontally scalable architecture that allows it to scale out across multiple servers as data volumes grow easily. Data is stored in flexible, self-describing documents instead of rigid tables, enabling faster iteration of application code.

What is PostgreSQL?

PostgreSQL is a powerful, open-source object-relational database system that has been actively developed for over 35 years. It combines SQL capabilities with advanced features to store and scale complex data workloads safely.

One of PostgreSQL’s core strengths is its proven architecture focused on reliability, data integrity, and robust functionality. It runs on all major operating systems, has been ACID-compliant since 2001, and offers powerful extensions like the popular PostGIS for geospatial data.

Differences between MongoDB & PostgreSQL & Reasons to Sync

I have found that MongoDB is a distributed database that excels in handling modern transactional and analytical applications, particularly for rapidly changing and multi-structured data. On the other hand, PostgreSQL is an SQL database that provides all the features I need from a relational database.

Differences

• Data Model: MongoDB uses a document-oriented data model, but PostgreSQL uses a table-based relational model.
• Query Language: MongoDB uses query syntax, but PostgreSQL uses SQL.
• Scaling: MongoDB scales horizontally through sharding, but PostgreSQL scales vertically on powerful hardware.
• Community Support: PostgreSQL has a large, mature community support, but MongoDB’s is still growing.

Reasons to migrate from MongoDB to PostgreSQL:

• Better for larger data volumes: While MongoDB works well for smaller data volumes, PostgreSQL can handle larger amounts of data more efficiently with its powerful SQL engine and indexing capabilities.
• SQL and strict schema: If you need to leverage SQL or require a stricter schema, PostgreSQL’s relational approach with defined schemas may be preferable to MongoDB’s schemaless flexibility.
• Transactions: PostgreSQL offers full ACID compliance for transactions, MongoDB has limited support for multi-document transactions.
• Established solution: PostgreSQL has been around longer and has an extensive community knowledge base, tried and tested enterprise use cases, and a richer history of handling business-critical workloads.
• Cost and performance: For large data volumes, PostgreSQL’s performance as an established RDBMS can outweigh the overhead of MongoDB’s flexible document model, especially when planning for future growth.
• Integration: If you need to integrate your database with other systems that primarily work with SQL-based databases, PostgreSQL’s SQL support makes integration simpler.

MongoDB to PostgreSQL: 3 Migration Approaches

Method 1: How to Migrate Data from MongoDB to PostgreSQL Manually?

To manually transfer data from MongoDB to PostgreSQL, I’ll follow a straightforward ETL (Extract, Transform, Load) approach. Here’s how I do it:

Prerequisites and Configurations

1. MongoDB Version: For this demo, I am using MongoDB version 4.4.
2. PostgreSQL Version: Ensure you have PostgreSQL version 12 or higher installed.
3. MongoDB and PostgreSQL Installation: Both databases should be installed and running on your system.
4. Command Line Access: Make sure you have access to the command line or terminal on your system.
5. CSV File Path: Ensure the CSV file path specified in the COPY command is accurate and accessible from PostgreSQL.

Step 1: Extract the Data from MongoDB

First, I use the mongoexport utility to export data from MongoDB. I ensure that the exported data is in CSV file format. Here’s the command I run from a terminal:

mongoexport --host localhost --db bookdb --collection books --type=csv --out books.csv --fields name,author,country,genre

This command will generate a CSV file named books.csv. It assumes that I have a MongoDB database named bookdb with a book collection and the specified fields.

Step 2: Create the PostgreSQL Table

Next, I create a table in PostgreSQL that mirrors the structure of the data in the CSV file. Here’s the SQL statement I use to create a corresponding table:

CREATE TABLE books (

    id SERIAL PRIMARY KEY,

    name VARCHAR NOT NULL,

    position VARCHAR NOT NULL,

    country VARCHAR NOT NULL,

    specialization VARCHAR NOT NULL

);

This table structure matches the fields exported from MongoDB.

Step 3: Load the Data into PostgreSQL

Finally, I use the PostgreSQL COPY command to import the data from the CSV file into the newly created table. Here’s the command I run:

COPY books(name,author,country,genre)

FROM 'C:/path/to/books.csv' DELIMITER ',' CSV HEADER;

This command loads the data into the PostgreSQL books table, matching the CSV header fields to the table columns.

Pros and Cons of the Manual Method

Pros:

• It’s easy to perform migrations for small data sets.
• I can use the existing tools provided by both databases without relying on external software.

Cons:

• The manual nature of the process can introduce errors.
• For large migrations with multiple collections, this process can become cumbersome quickly.
• It requires expertise to manage effectively, especially as the complexity of the requirements increases.

Method 2: How to Migrate Data from MongoDB to PostgreSQL using Airbyte

Airbyte is an open-source data integration platform. Here are the steps to install airbyte. This can be fairly elaborate and hard for someone setting up the first time, so take this approach with a pinch of salt. Plus, since Airbyte is open source, I would not recommend using it for large-scale production workloads. The tool is sometimes known to be buggy.

I already had Airbyte set up – so will directly jump to showcasing how we can achieve the MongoDB to PostgreSQL sync.

a. Log in to Airbyte Account: I log in to my Airbyte account.

b. Set up Source Connector: I set up a source connector by clicking on New source and selecting MongoDB from the list of sources. I provide the necessary connection details to a MongoDB database instance and click on Set up source.

c. Configure Destination Connector: I configure a destination connector by clicking on Destinations and selecting Create destination. I choose PostgreSQL as the destination and enter the relevant connection parameters. I click on Set up destination to complete the process.

d. Set up Connection: I set up the Airbyte connection between the source and the destination by clicking on Connections and selecting New Connection. I selected the source and destination I created earlier. The collections in MongoDB will be automatically detected, and I can choose the replication mode and the frequency of replication. I click on the Set up connection button to start the syncing process.

What I truly appreciate about Airbyte is its ability to abstract away the complexities of cross-database schema mapping and data transformation. 

Of course, for more advanced customization needs, Airbyte allows me to leverage its Python integration to write custom data manipulation code when required. But, for most of the MongoDB to PostgreSQL migrations, the existing features are more than sufficient.

Method 3: How to Migrate Data from MongoDB to PostgreSQL using Hevo Data

As someone who has leveraged Hevo Data for migrating between MongoDB and PostgreSQL, I can attest to its efficiency as a no-code ELT platform. What stands out for me is the seamless integration with transformation capabilities and auto schema mapping. Let me walk you through the easy 2-step process:

a. Configure MongoDB as your Source: Connect your MongoDB account to Hevo’s platform by configuring MongoDB as a source connector. Hevo provides an in-built MongoDB integration that allows you to set up the connection quickly.

2. Set PostgreSQL as your Destination: Select PostgreSQL as your destination. Here, you need to provide necessary details like database host, user and password.

You have successfully synced your data between MongoDB and PostgreSQL. It is that easy!

I would choose Hevo Data for migrating data from MongoDB to PostgreSQL because it simplifies the process, ensuring seamless integration and reducing the risk of errors. With Hevo Data, I can easily migrate my data, saving time and effort while maintaining data integrity and accuracy.

What’s your pick?

When deciding how to migrate your data from MongoDB to PostgreSQL, the choice largely depends on your specific needs, technical expertise, and project scale.

• Manual Method: If you prefer granular control over the migration process and are dealing with smaller datasets, the manual ETL approach is a solid choice. This method allows you to manage every step of the migration, ensuring that each aspect is tailored to your requirements.
• Airbyte: For those who favor a powerful, flexible, and open-source solution, Airbyte is an excellent option. Its ability to handle complex migrations with ease and provide advanced customization through Python integration makes it ideal for both small and large-scale projects.
• Hevo Data: If simplicity and efficiency are your top priorities, Hevo Data’s no-code platform is perfect. With its seamless integration, automated schema mapping, and real-time transformation features, Hevo Data offers a hassle-free migration experience, saving you time and reducing the risk of errors.

Want to take Hevo for a spin? Sign Up for a 14-day free trial and experience the feature-rich Hevo suite firsthand. Also, check out our unbeatable Hevo Pricing to choose the best plan for your organization.

The choice is yours now. Have any questions regarding data migration? Comment and tell us about your experience of migrating data from MongoDB to PostgreSQL. 

Frequently Asked Questions

Q1. How to convert MongoDB to Postgres?

• Step 1: Extract Data from MongoDB using mongoexport Command.
• Step 2: Create a Product Table in PostgreSQL to Add the Incoming Data.
• Step 3: Load the Exported CSV from MongoDB to PostgreSQL.

Q2. What is the best practice for PostgreSQL data migration?

The most effective approach to migrating a PostgreSQL database involves using native tools like pg_dump for exporting data from the source database and pg_restore for importing data into the target database. This method ensures reliability and flexibility in managing database schemas and data, making it a popular choice for many database migrations