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2 Unconventional Approaches to Connect PostgreSQL and MongoDB

Are you looking to establish a seamless connection between PostgreSQL to MongoDB? This comprehensive guide explores two unconventional yet powerful approaches to bridge the gap between these popular databases. By leveraging these techniques, you can unlock new possibilities for data integration and streamline your data management processes. PostgreSQL, known for its robustness and reliability, excels in structured data management.

While MongoDB, a leading NoSQL database, offers flexibility and scalability for unstructured data. Combining the strengths of both databases can provide a comprehensive solution for diverse data requirements. This guide delves into two unconventional approaches beyond traditional connecting PostgreSQL and MongoDB. By adopting these innovative techniques, you can overcome the limitations of conventional approaches and discover new avenues for data integration.

What is MongoDB?

MongoDB, a leading NoSQL database, has gained immense popularity in modern data management. MongoDB is designed to handle unstructured and semi-structured data; MongoDB offers a flexible and scalable solution for organizations dealing with diverse data types. At its core, MongoDB is a document-oriented database that stores data in a JSON-like format called BSON (Binary JSON). This flexible data model allows for dynamic schema and supports nested structures, making it an ideal choice for applications with evolving data requirements. Unlike traditional relational databases, MongoDB doesn't rely on fixed table schemas, allowing developers to iterate and adapt their data models as needed.

Key Features of MongoDB:

  • Flexible Document Model: MongoDB employs a flexible document model, storing data in JSON-like documents. This allows for dynamic and schema-less data structures, making it easy to handle evolving data models and accommodate changes without downtime or complex migrations.
  • Scalability and High Performance: MongoDB is built to handle large-scale data-intensive applications, offering horizontal scalability through shading. By distributing data across multiple servers, MongoDB can support high write and read throughput, ensuring optimal performance even with massive data.
  • Rich Query Language: MongoDB provides a powerful and expressive query language that supports a wide range of operations, including filtering, sorting, aggregation, and geospatial queries. This allows developers to retrieve and manipulate data flexibly and efficiently.
  • Indexing and Full-text Search: MongoDB supports various indexing techniques, including single-field, compound, and geospatial indexes, enabling fast and efficient data retrieval. MongoDB also offers robust full-text search capabilities, empowering users to perform advanced text-based searches across large datasets.
  • High Availability and Fault Tolerance: MongoDB offers built-in replication and automatic failover mechanisms, ensuring high availability and fault tolerance. With replica sets, data is automatically synchronised across multiple nodes, providing redundancy and eliminating single points of failure.
  • Horizontal and Vertical Scaling: MongoDB allows for both horizontal and vertical scaling. Horizontal scaling involves adding more servers to distribute the load, while vertical scaling involves upgrading hardware resources to handle increased data and traffic.
  • Integration with Popular Tools and Frameworks: MongoDB integrates seamlessly with popular programming languages, frameworks, and tools. This includes support for various drivers, ORMs, and connectors, making integrating MongoDB into your existing technology stack easy.
  • Security and Access Control: MongoDB offers robust security features, including authentication, encryption, and role-based access control (RBAC). Administrators can define fine-grained access controls to ensure data privacy and prevent unauthorised access.
  • Document Validation and Schema Validation: MongoDB allows for document validation, where you can define rules and constraints on the structure and content of documents. This helps enforce data integrity and maintain consistency within the database.
  • Comprehensive Ecosystem: MongoDB has a vibrant and extensive ecosystem with a wide range of community-driven plugins, libraries, and tools available. This enables developers to leverage additional functionalities and enhance their MongoDB deployments.


What is PostgreSQL?

PostgreSQL, often called Postgres, is a powerful and open-source relational database management system (RDBMS) that has gained widespread popularity in the software development community. Known for its reliability, scalability, and robustness, PostgreSQL offers comprehensive features and advanced capabilities for managing structured data efficiently. PostgreSQL follows the relational database model, which organizes data into tables with rows and columns. It provides a strong foundation for handling structured data and supports various data types, including numeric, text, date/time, and JSON. The extensibility of PostgreSQL allows users to define custom data types, operators, and functions to meet specific application requirements.

Key Features of PostgreSQL:

  • Advanced SQL Support: PostgreSQL offers a comprehensive and standards-compliant implementation of the SQL language. It supports various SQL features, including complex queries, triggers, stored procedures, and user-defined functions. This allows developers to leverage the full power of SQL for efficient data manipulation and analysis.
  • Extensibility and Customisability: PostgreSQL provides a unique extension system that allows users to extend the database functionality by adding custom data types, operators, and functions. This extensibility enables developers to tailor the database to their requirements, making it highly adaptable to various use cases.
  • Data Integrity and Reliability: PostgreSQL ensures data integrity through the implementation of ACID (Atomicity, Consistency, Isolation, Durability) properties. It provides robust transaction support, allowing concurrent access to the database while maintaining data consistency and reliability.
  • Concurrency and Scalability: PostgreSQL excels in handling concurrent workloads and scaling to meet growing demands. It employs a multi-version concurrency control (MVCC) mechanism, which allows multiple transactions to access the database simultaneously without blocking each other. PostgreSQL offers various scalability options, including table partitioning and parallel query execution.
  • Built-in Replication and High Availability: PostgreSQL supports various replication methods, such as streaming and logical replication, to ensure high availability and data redundancy. These replication mechanisms enable the creation of standby servers that can be seamlessly promoted to primary servers in the event of failures.
  • Full-text Search and Text Indexing: PostgreSQL includes powerful full-text search capabilities, allowing users to perform complex text-based searches efficiently. It supports features like phrase matching, stemming, and ranking, making it suitable for applications that require advanced search functionality.
  • Geospatial Capabilities: PostgreSQL has robust support for geospatial data and offers a wide range of geospatial functions and operators. This enables the storage and querying of spatial data, making it ideal for applications that deal with mapping, location-based services, and geographic information systems (GIS).
  • JSON and NoSQL Capabilities: PostgreSQL has native support for JSON (JavaScript Object Notation) data, allowing developers to store, query, and manipulate JSON documents within the database. This feature bridges the gap between relational and NoSQL databases, providing flexibility for handling semi-structured and unstructured data.
  • Security and Access Controls: PostgreSQL offers advanced security features, including authentication mechanisms, SSL encryption, and role-based access control (RBAC). It allows administrators to define fine-grained access controls and manage user privileges to ensure data privacy and security.
  • Active Community and Ecosystem: PostgreSQL has a vibrant and active community of developers, contributing to its continuous improvement and enhancement. Its rich ecosystem has many extensions, tools, and libraries that extend its functionality and integrate with popular frameworks and programming languages.


The main differences between MongoDB and PostgreSQL

MongoDB and PostgreSQL are popular database management systems, but they differ significantly in their data storage, query language, and modeling approach. Understanding these differences is crucial when deciding which database to use for a specific project.

1. Data Model:

MongoDB follows a document-oriented data model, where data is stored in flexible, JSON-like documents. This allows for dynamic and schema-less data structures, making it suitable for applications with evolving data requirements. On the other hand, PostgreSQL follows a traditional relational data model, organizing data into tables with predefined schemas and enforcing strict data integrity rules.

2. Scalability:

MongoDB excels in horizontal scalability, allowing for easy data distribution across multiple servers and seamless scaling by adding more nodes to a cluster. It achieves this through sharding, which partitions data across shards. Conversely, PostgreSQL is primarily designed for vertical scalability, where a single server is scaled up by adding more resources such as CPU and RAM.

3. Query Language:

MongoDB uses a flexible query language called MongoDB Query Language (MQL), which is based on JavaScript syntax and allows for complex document-based queries. It supports powerful features like aggregation pipelines and geospatial queries. Conversely, PostgreSQL uses SQL (Structured Query Language), a standardized language for querying relational databases. SQL offers various querying capabilities and advanced features such as joins, subqueries, and window functions.

4. Transactions and ACID Compliance:

PostgreSQL has a strong focus on data integrity and provides full ACID (Atomicity, Consistency, Isolation, Durability) compliance. It supports robust transaction management, grouping multiple operations as a single atomic unit. MongoDB introduced multi-document transactions in recent versions but still lacks full ACID compliance for distributed transactions.

5. Schema Flexibility:

MongoDB offers schema flexibility, allowing documents within a collection to have different structures. This makes it suitable for use cases where data evolves or has varying data structures within a collection. In contrast, PostgreSQL enforces a predefined schema, requiring strict adherence to table structures and data types.

6. Indexing:

Both MongoDB and PostgreSQL support indexing for efficient data retrieval. MongoDB uses index types, including single-field, compound, multi-key, and geospatial indexes. PostgreSQL offers various indexing options, including B-tree, hash, GiST (Generalized Search Tree), and GIN (Generalized Inverted Index).

7. Replication and High Availability:

MongoDB has built-in support for automatic sharding and replication, allowing for high availability and fault tolerance. It provides replica sets and self-healing clusters with primary and secondary nodes. PostgreSQL also supports replication through various methods, including streaming and logical.

8. Community and Ecosystem:

Both MongoDB and PostgreSQL have active and thriving communities. MongoDB has a vibrant developer community and offers a wide range of tools, libraries, and frameworks that integrate seamlessly with the database. PostgreSQL, an open-source project with a long history, has a mature ecosystem with extensive community support and many extensions and plugins.

When to use MongoDB vs. PostgreSQL

Choosing between MongoDB and PostgreSQL depends on various factors, including the nature of your data, scalability requirements, and the specific needs of your application.

Use MongoDB When:

  • Flexible Data Structures: If your application deals with unstructured or semi-structured data, MongoDB's document-oriented model provides the flexibility to store and manipulate data without strict schemas. It allows you to evolve your data model and accommodate changing requirements.
  • Scalability and High Write Throughput: MongoDB's native support for horizontal scaling makes it an ideal choice for applications that require high write throughput and the ability to distribute data across multiple servers. It excels in handling massive amounts of data and can seamlessly scale to meet growing demands.
  • Real-Time Analytics and Personalization: MongoDB's rich querying capabilities and flexible data model suit real-time analytics and personalization scenarios. It allows you to perform complex aggregations, geospatial queries, and text search operations efficiently.
  • Rapid Prototyping and Agile Development: MongoDB's schema-less nature enables rapid prototyping and agile development cycles. It eliminates the need to define a rigid schema upfront, allowing developers to iterate quickly and accommodate changes during development.

Use PostgreSQL When:

  • Structured and Relational Data: If your data has a well-defined structure and requires strict adherence to relational principles, PostgreSQL's robust SQL support and adherence to ACID properties make it an excellent choice. It ensures data integrity and provides a standardized querying language for complex relational operations.
  • Complex Joins and Transactions: PostgreSQL's SQL capabilities shine in scenarios that involve complex joins, subqueries, and transactional operations. It allows you to manipulate advanced data, combine data from multiple tables, and ensure consistency through transaction management.
  • Data Integrity and Compliance: If your application demands strong data integrity, PostgreSQL's adherence to ACID properties and comprehensive support for constraints, triggers, and foreign key relationships make it the go-to option. It offers referential integrity, data validation, and strict type checking.
  • Mature Ecosystem and Community Support: PostgreSQL has a mature ecosystem with extensive community support and a wide range of extensions and plugins. If you require specific functionality or integration with popular frameworks and tools, PostgreSQL's ecosystem provides a wealth of options.

Consider Hybrid Approaches

In some cases, a hybrid approach that combines the strengths of MongoDB and PostgreSQL may be suitable. For example, you can use MongoDB for high write throughput and real-time analytics while leveraging PostgreSQL for complex relational operations and ensuring data integrity. Ultimately, the choice between MongoDB and PostgreSQL depends on understanding your application's requirements. Consider data structure, scalability needs, query complexity, and ecosystem support to make an informed decision. Evaluating the trade-offs and selecting the database management system that best aligns with your project's goals and long-term vision is crucial.

Want to transfer data from PostgreSQL to MongoDB

Proper preparation is essential to ensure a smooth and successful transition if you switch from PostgreSQL to MongoDB. Migrating from one database to another requires careful planning and execution.

  • Evaluate Data Structure: Start by evaluating your data structure in PostgreSQL and understanding how it aligns with MongoDB's document-oriented model. Identify any schema changes or data transformations that may be required during migration. Consider the differences in data types, indexing options, and query patterns between the two databases.
  • Analyze Application Dependencies: Examine your application's dependencies on PostgreSQL-specific features, such as stored procedures, triggers, or advanced SQL constructs. Determine how these functionalities can be translated or replicated in MongoDB. It may require rewriting certain parts of your application logic or utilizing MongoDB's features and capabilities effectively.
  • Plan for Data Migration: Develop a comprehensive data migration strategy to ensure a seamless data transfer from PostgreSQL to MongoDB. Consider using specialized migration tools or frameworks to automate the process and efficiently handle data transformation tasks. Test the migration process on a subset of data before executing it on the entire dataset to identify and address potential issues or performance concerns.
  • Update Application Code: Update your application code to replace PostgreSQL-specific queries, syntax, and database access methods with MongoDB equivalents. Familiarize yourself with MongoDB's query language, document structure, and indexing options to optimize the performance of your application. Ensure the necessary drivers or libraries are installed and configured correctly for MongoDB connectivity.
  • Test and Validate: Thoroughly test the migrated data and application functionality in the MongoDB environment. Validate that the data has been accurately transferred and that the application behaves as expected. Conduct performance testing to ensure the new database meets the required performance benchmarks and can handle the anticipated workload.
  • Train and Educate: Provide training and education to your development team to familiarize them with MongoDB's features, best practices, and performance optimization techniques. Encourage knowledge sharing and collaboration to maximize the benefits of the new database and leverage its unique capabilities.
  • Implement Monitoring and Maintenance: Set up appropriate monitoring and maintenance processes for your MongoDB deployment. Configure monitoring tools to track performance metrics, identify bottlenecks, and proactively address any issues that may arise. Establish regular backup and recovery procedures to safeguard your data.

Method 1: Manual ETL Process to Set Up MongoDB to PostgreSQL Integration

If you prefer a manual approach to integrating MongoDB with PostgreSQL, you can follow a step-by-step ETL (Extract, Transform, Load) process to transfer data between the two databases. This method allows you to control and customize the migration process according to your specific requirements.

Step 1: Extract Data from MongoDB (using mongoexport Command)

To begin the integration process, you need to extract data from MongoDB. MongoDB provides a command-line tool called "mongoexport" to export data in JSON or CSV format. Use the appropriate mongoexport Command to extract the desired data from your MongoDB database.

Step 2: Create a Product Table in PostgreSQL to Store the Incoming Data.

It would be best to create a corresponding table in your PostgreSQL database to store the incoming data. Define the table structure, including the column names, data types, and necessary constraints. Ensure that the table structure aligns with the data extracted from MongoDB to avoid any data inconsistencies.

Step 3: Load the Exported CSV to PostgreSQL

Once you have the extracted data in CSV format, you can load it into the PostgreSQL database using the COPY command or any other suitable method. Map the columns in the CSV file to the corresponding columns in the PostgreSQL table. Verify the data mapping and ensure that the data is loaded accurately. It's important to note that this manual ETL process requires careful attention to detail and may be time-consuming, especially for large datasets. It also lacks dedicated ETL tools or connectors' automation and real-time synchronisation capabilities.

However, this method provides flexibility and gives you more control over the migration process. Remember to handle any data transformations or conversions required during the migration process. Depending on the nature of the data, you may need to modify the data types or structure to ensure compatibility between MongoDB and PostgreSQL.

Limitation of Manual ETL Process to Set Up MongoDB to PostgreSQL Integration

  • Time and Effort: The manual ETL process requires significant time and effort, especially for large datasets. Extracting data from MongoDB, creating tables in PostgreSQL, and loading the data can be time-consuming. Additionally, mapping columns and ensuring data consistency can be complex and error-prone, leading to further delays.
  • Lack of Real-Time Synchronization: The manual ETL process does not offer real-time synchronization between MongoDB and PostgreSQL. It is a one-time data transfer method, and any changes made in MongoDB after the initial extraction will not be automatically reflected in the PostgreSQL database. You must repeat the ETL process periodically to keep the data in sync.
  • Complex Data Transformations: The manual ETL process can become challenging if your data requires complex transformations or data type conversions. Handling these transformations manually increases the risk of errors and data inconsistencies. Dedicated ETL tools or connectors often provide built-in functionality for handling complex data transformations more efficiently.
  • Scalability: As the volume of data increases, the manual ETL process becomes less scalable. Handling large datasets manually can lead to performance issues and inefficiencies. Dedicated ETL tools are designed to handle large-scale data integration tasks more effectively.
  • Maintenance and Updates: When using the manual ETL process, any changes in the data structure or schema in MongoDB or PostgreSQL require manual updates to the integration process. This can become cumbersome and time-consuming, especially in evolving data environments.

Method 2: Using Rest API to pipe Data from MongoDB to PostgreSQL

Boltic offers a comprehensive integration solution that enables seamless connectivity between PostgreSQL and MongoDB. With Boltic's integration capabilities, you can streamline transferring data from MongoDB to PostgreSQL and ensure data consistency and reliability. Here are the steps to connect PostgreSQL to MongoDB using Boltic:

Step 1: Sign up for Boltic:

Visit the Boltic website and create an account. Boltic provides a user-friendly interface and intuitive features that make the integration process hassle-free.

Step 2: Create a Connection:

Once you have signed up, connect your PostgreSQL and MongoDB databases within the Boltic platform. Provide the necessary connection details, such as database credentials and connection endpoints.

Step 3: Select MongoDB as the Source:

In the Boltic integration interface, choose MongoDB as the data source from which you want to extract data.

Step 4: Configure PostgreSQL as the Target:

Specify PostgreSQL as the destination database to pipe the MongoDB data. Provide the required PostgreSQL connection details.

Step 5: Map Data Fields:

Map the fields from MongoDB to the corresponding columns in PostgreSQL. This step ensures that the data is transferred accurately and maintains its integrity during the migration.

Step 6: Initiate the Data Transfer:

Once the configuration is complete, initiate the data transfer process. Boltic's integration engine will securely and efficiently transfer the data from MongoDB to PostgreSQL.

Step 7: Monitor and Verify:

Monitor the data transfer process in real-time using Boltic's dashboard. You can track the progress, check for errors or inconsistencies, and ensure the data is transferred successfully.

Using Rest API, powered by Boltic, streamlines the integration process by providing a user-friendly interface, robust connectivity options, and efficient data transfer mechanisms. Rest API automates the data transfer between MongoDB and PostgreSQL, eliminating the need for manual ETL processes and reducing the risk of errors and data inconsistencies. With Rest API, you can schedule periodic data transfers, ensuring that your PostgreSQL database is always up to date with the latest data from MongoDB. The seamless integration offered by Rest API simplifies the overall process, allowing you to focus on leveraging your data and deriving valuable insights.


We explored two unconventional approaches to connect PostgreSQL and MongoDB, offering flexibility and options when integrating these powerful databases. By manually setting up the integration through an ETL process or utilizing Rest API powered by Boltic, you can establish a seamless connection between PostgreSQL and MongoDB, enabling efficient data transfer and synchronization. Whether you choose the manual ETL process or leverage Rest API, each approach has advantages and considerations.

The manual ETL process provides control and customisation, while Rest API simplifies the integration with its user-friendly interface and automation capabilities. Both methods offer opportunities to overcome the challenges of connecting PostgreSQL and MongoDB, allowing you to unlock the potential of your data. Whichever method you choose, remember to consider your specific requirements, data volume, and complexity of the integration. Evaluate the benefits and limitations of each approach to determine the best fit for your project. With the right approach, you can seamlessly connect PostgreSQL and MongoDB, empowering your data-driven initiatives and maximizing the potential of both databases.


How to connect MongoDB to PostgreSQL?

To connect MongoDB to PostgreSQL, you can utilize various methods such as manual ETL processes, using third-party integration tools, or leveraging specialized platforms like Boltic. These approaches enable data transfer and synchronization between the two databases, allowing you to connect MongoDB and PostgreSQL seamlessly.

Is PostgreSQL easier than MongoDB?

The ease of use depends on your requirements and familiarity with the database systems. PostgreSQL is known for its robustness and adherence to SQL standards, making it a popular choice for traditional relational database needs. MongoDB, on the other hand, is a NoSQL database known for its flexibility and scalability, particularly in handling unstructured and complex data. The choice between PostgreSQL and MongoDB should be based on your specific use case and preferences.

How to manually connect to MongoDB?

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To manually connect to MongoDB, you can use MongoDB's native drivers or client libraries in your preferred programming language. These drivers provide APIs and methods to connect to your MongoDB instance, allowing you to interact with the database and perform various operations such as querying, inserting, updating, and deleting data.

Which one is better: MongoDB or PostgreSQL?

The choice between MongoDB and PostgreSQL depends on your specific requirements and the nature of your project. MongoDB is well-suited for handling large volumes of unstructured or semi-structured data, providing high scalability and flexibility. PostgreSQL, on the other hand, excels in managing structured data and offers strong ACID compliance. The decision should consider factors such as data structure, scalability needs, performance requirements, and the complexity of your project.

How to move data from MongoDB to PostgreSQL?

There are multiple approaches to moving data from MongoDB to PostgreSQL. One option is to use ETL (Extract, Transform, Load) processes, where you extract data from MongoDB, transform it into a suitable format for PostgreSQL, and then load it into the PostgreSQL database. Another option is to utilize third-party migration tools or platforms that provide streamlined data migration capabilities between MongoDB and PostgreSQL.

How does MongoDB connect to the database?

MongoDB connects to the database using its native drivers or client libraries, which provide the necessary interfaces to establish a connection with a MongoDB instance. These drivers allow developers to interact with the database, perform CRUD (Create, Read, Update, Delete) operations, and leverage MongoDB's powerful querying capabilities. Additionally, MongoDB supports various authentication mechanisms to ensure secure connections to the database.
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