MQTT and MongoDB: Crafting Seamless Synergy for IoT Data Mangement

EMQ Technologies
5 min readDec 5, 2023

Table of Contents

What is MongoDB?

MongoDB is a document database, aims to streamline application development and scalability. In contrast to conventional relational databases, which employ tables for data storage, MongoDB uses documents. This innovative approach enhances flexibility and helps MongoDB to adeptly accommodate evolving data patterns.

Document data usually comes in JSON, BSON, or XML formats, which are highly readable and scalable, and thus ideal for storing semi-structured or structured data. MongoDB implements various optimizations designed for document data to improve its performance and scalability. For example, MongoDB enables document compression, which reduces storage space needs. Moreover, MongoDB supports time partitioning, which simplifies the querying and analysis of timestamped data. MongoDB’s readability, scalability, and fast data ingestion and storage make it especially suitable for IoT scenarios.

How Does MongoDB work?

MongoDB organizes data using key-value pairs, a format that simplifies the storage and retrieval of intricate data structures. MongoDB documents are composed of key-value pairs (i.e., BSON), which allow flexible data structures such as nested, array, etc. Notably, there’s no obligation to establish identical fields across different data sets, and uniform data types for the same fields are not mandatory. Meanwhile, MongoDB provides the flexibility to create indexes on document fields as needed by applications, enhancing the speed of data query operations.

MongoDB can rapidly adapt to diverse data types, efficiently representing complex data structures for a more intuitive data organization. Simultaneously, it permits users to dynamically introduce fields as required during business or state changes, eliminating the need to predefine all possible fields in advance. This feature proves valuable for accommodating new data types and attributes collected in the context of the Internet of Things.

Benefits of MongoDB in IoT Applications

Internet of Things devices generate a lot of diverse data, including telemetry data from sensors (usually in the form of time-series data), and client state and state changes (such as online status and current sensor values).

MongoDB boasts several distinctive advantages:

  1. Schemaless Document Storage: Data in MongoDB is stored in a document format, allowing users to store data with diverse structures in the same database without the need to predefine table structures. Support for array and nested documents enhances flexibility in representing complex IoT data structures.
  2. Powerful Query Language: MongoDB features a robust query language supporting a range of operations, including filtering, sorting, projection, aggregation, and so on.
  3. Distributed Database: MongoDB easily scales horizontally, supporting distributed database deployment with automatic data sharding to handle large-scale IoT data. It seamlessly scales alongside EMQX clusters.
  4. Replication and Fault Tolerance: MongoDB facilitates data replication by creating multiple copies, enhancing availability and fault tolerance. In the event of a primary node failure, the system seamlessly switches to a backup node.
  5. Time-series Data Processing: Starting from MongoDB 5.0, the platform offers support for time-series data collection. This feature efficiently stores time-series data, reducing disk occupancy and processing complexity.

MongoDB has schemaless flexibility that sets it apart from relational and time-series databases. This means it can easily handle different kinds of data without predefined table structures. It also supports frequent inserts, updates, and flexible queries on structured data.

MongoDB has two main uses for the IoT domain. First, it can record the latest status and events of devices, such as online and offline status, and monitor their behavior and anomalies. This helps to improve device security management. Second, MongoDB has distributed storage, large-scale data processing, and rich query capabilities that make it a great solution for storing telemetry data. It also has special support for time-series data, which allows it to serve as a back-end engine for storing and analyzing telemetry data. This can be used for various big data analysis and data mining tasks, providing users with more value and insights.

MongoDB’s flexibility and versatility make it a powerful tool for the development of IoT applications.

How to Integrate MongoDB with MQTT Using EMQX

EMQX is a leading MQTT Broker that offers ready-to-use features and seamless integration with MongoDB. It can update and store various types of device event and message data, and help users to quickly develop different kinds of business applications.

The EMQX Data Integration component, in collaboration with MongoDB, offers the following features:

  • Full MQTT 5.0 Support: Devices can connect to MongoDB using the MQTT 5.0 or 3.1.1 protocol through EMQX.
  • Rich Device Event Integration: EMQX can record the complete lifecycle event data of devices, such as online and offline status, subscriptions, message publishing and delivery, to MongoDB. This enables continuous recording and rich monitoring.
  • Reliable Data Ingestion: EMQX has message buffers to prevent data loss when MongoDB is not available.
  • Real-Time Data Transformation: Employing an SQL-based rule engine, EMQX allows for the extraction, filtering, enrichment, and transformation of data in transit.
  • Real-Time Metrics and Monitoring: EMQX can monitor the message transfers between the MQTT Broker and the time-series database in real-time.

Here are some use cases of the integration of MongoDB with EMQX in different IoT scenarios:

  • Smart Home: In the realm of IoT applications, smart homes stand out as a prominent use case. MongoDB plays a pivotal role by serving as a platform for storing and managing information related to smart home devices. It enables the real-time collection and storage of data from diverse sensors, facilitating intelligent control and optimization of smart home devices through data analysis and mining.
  • Smart City: The concept of a Smart City involves the comprehensive and intelligent management of urban areas using IoT technology. Document databases, with MongoDB as a notable example, contribute significantly to smart cities. It proves valuable in storing diverse information related to equipment and vehicles in urban transportation systems, providing real-time traffic data, and supporting intelligent traffic control.
  • Industrial Automation: Industrial automation leverages IoT technology to achieve real-time monitoring and control of industrial production environments through networked devices and sensors. MongoDB is employed to store and manage various data generated by industrial equipment, facilitating real-time scheduling and optimization of industrial processes.


The fusion of MQTT and EMQX with MongoDB offers a robust solution for IoT device management and message storage. EMQX stands out as the preferred option for contemporary IoT projects, boasting high reliability, scalability, and impressive message throughput. Paired with MongoDB’s exceptional schemaless flexibility and distributed storage capabilities, this combination efficiently stores and manages IoT data. Together, they enable the effective storage and management of IoT data, leading to a more comprehensive extraction of data value.

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EMQ Technologies

EMQ is an open-source IoT data infrastructure software provider, delivering the world’s leading open-source MQTT message broker and stream processing database.