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.
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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: 2 Migration Approaches
Method 1: Using the mongoexport command.
This method manually transfers Data from MongoDB to PostgreSQL using the command line. Users need to write long commands, which is more error-prone.
Method 2: Using Hevo for MongoDB to PostgreSQL.
Hevo Data provides an automated, no-code solution for MongoDB to PostgreSQL integration. It not only migrates data effortlessly but also enriches and transforms it into an analysis-ready form without any coding required.
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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
- MongoDB Version: For this demo, I am using MongoDB version 4.4.
- PostgreSQL Version: Ensure you have PostgreSQL version 12 or higher installed.
- MongoDB and PostgreSQL Installation: Both databases should be installed and running on your system.
- Command Line Access: Make sure you have access to the command line or terminal on your system.
- 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.
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Method 2: 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.
- 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!
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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.
Additional Resources on MongoDB to PostgreSQL
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.
- 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.
FAQ on MongoDB to PostgreSQL
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.
Is Postgres better than MongoDB?
Choosing between PostgreSQL and MongoDB depends on your specific use case and requirements
How to sync MongoDB and PostgreSQL?
Syncing data between MongoDB and PostgreSQL typically involves implementing an ETL process or using specialized tools like Hevo, Stitch etc.
How to transfer data from MongoDB to SQL?
1. Export Data from MongoDB
2. Transform Data (if necessary)
3. Import Data into SQL Database
4. Handle Data Mapping
Chirag is a seasoned support engineer with over 7 years of experience, including over 4 years at Hevo Data, where he's been pivotal in crafting core CX components. As a team leader, he has driven innovation through recruitment, training, process optimization, and collaboration with multiple technologies. His expertise in lean solutions and tech exploration has enabled him to tackle complex challenges and build successful services.