Choosing the right database is a critical choice when building any software application. All databases have different strengths and weaknesses when it comes to performance, so deciding which database has the most benefits and the most minor downsides for your specific use case and data model is an important decision. Below you will find an overview of the key concepts, architecture, features, use cases, and pricing models of MongoDB and QuestDB so you can quickly see how they compare against each other.

The primary purpose of this article is to compare how MongoDB and QuestDB perform for workloads involving time series data, not for all possible use cases. Time series data typically presents a unique challenge in terms of database performance. This is due to the high volume of data being written and the query patterns to access that data. This article doesn’t intend to make the case for which database is better; it simply provides an overview of each database so you can make an informed decision.

MongoDB vs QuestDB Breakdown


 
Database Model

Document database

Time series database

Architecture

MongoDB uses a flexible, JSON-like document model for storing data, which allows for dynamic schema changes without downtime. It supports ad hoc queries, indexing, and real-time aggregation. MongoDB can be deployed as a standalone server, in a replica set configuration for high availability, or as a sharded cluster for horizontal scaling. It is also available as a managed cloud service called MongoDB Atlas, which provides additional features like automated backups, monitoring, and global distribution.

QuestDB is designed for horizontal scaling, enabling you to distribute data and queries across multiple nodes for increased performance and availability. It can be deployed on-premises, in the cloud, or as a hybrid solution, depending on your infrastructure needs and preferences.

License

SSPL for community edition, commercial licenses for other versions

Apache 2.0

Use Cases

Content management systems, mobile applications, real-time analytics, IoT data management, e-commerce platforms

Monitoring, observability, IoT, Real-time analytics, Financial services, High-frequency trading

Scalability

Horizontally scalable with support for data sharding, replication, and automatic load balancing

High-performance with support for horizontal scaling and multi-threading

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MongoDB Overview

MongoDB is a popular, open-source NoSQL database launched in 2009. Designed to handle large volumes of unstructured and semi-structured data, MongoDB offers a flexible, schema-less data model, horizontal scalability, and high performance. Its ease of use, JSON-based document storage, and support for a wide range of programming languages have contributed to its widespread adoption across various industries and applications.

QuestDB Overview

QuestDB is an open-source relational column-oriented database designed specifically for time series and event data. It combines high-performance ingestion capabilities with SQL analytics, making it a powerful tool for managing and analyzing large volumes of time-based data. QuestDB addresses the challenges of handling high throughput and provides a simple way to analyze ingested data through SQL queries. It is well-suited for use cases such as financial market data and application metrics.


MongoDB for Time Series Data

Although MongoDB is a general-purpose NoSQL database, it can be used for storing and processing time series data. The flexible data model of MongoDB allows for easy adaptation to the evolving structure of time series data, such as the addition of new metrics or the modification of existing ones. MongoDB provides built-in support for time-to-live (TTL) indexes, which automatically expire old data after a specified time period, making it suitable for managing large volumes of time series data with a limited storage capacity. MongoDB has also recently added a custom columnar storage engine and time series collection for time series use cases, meant to improve performance over the default MongoDB storage engine in terms of data compression and query performance.

QuestDB for Time Series Data

QuestDB excels in managing and analyzing time series data. With its high-performance ingestion capabilities, it can handle high data throughput, making it suitable for real-time data ingestion scenarios. QuestDB’s SQL extensions for time series enable users to perform real-time analytics and gain valuable insights from their time-stamped data. Whether it’s financial market data or application metrics, QuestDB simplifies the process of ingesting and analyzing time series data through its fast SQL queries and operational simplicity.


MongoDB Key Concepts

Some key terminology and concepts specific to MongoDB include:

  • Database: A MongoDB database is a container for collections, which are groups of related documents.
  • Collection: A collection in MongoDB is analogous to a table in relational databases, holding a set of documents.
  • Document: A document in MongoDB is a single record, stored in a JSON-like format called BSON (Binary JSON). Documents within a collection can have different structures.
  • Field: A field is a key-value pair within a document, similar to an attribute or column in a relational database.
  • Index: An index in MongoDB is a data structure that improves the query performance on specific fields within a collection.

QuestDB Key Concepts

  • Time Series: QuestDB focuses on time series data, which represents data points indexed by time. It is optimized for storing and processing time-stamped data efficiently.
  • Column-Oriented: QuestDB employs a column-oriented storage format, where data is organized and stored column by column rather than row by row. This format enables efficient compression and faster query performance.
  • SQL Extensions: QuestDB extends the SQL language with functionalities specifically tailored for time series data. These extensions facilitate real-time analytics and allow users to leverage familiar SQL constructs for querying time-based data.


MongoDB Architecture

MongoDB’s architecture is centered around its flexible, document-based data model. As a NoSQL database, MongoDB supports a schema-less structure, which allows for the storage and querying of diverse data types, such as nested arrays and documents. MongoDB can be deployed as a standalone server, a replica set, or a sharded cluster. Replica sets provide high availability through automatic failover and data redundancy, while sharded clusters enable horizontal scaling and load balancing by distributing data across multiple servers based on a shard key.

QuestDB Architecture

QuestDB follows a hybrid architecture that combines features of columnar and row-based databases. It leverages a column-oriented storage format for efficient compression and query performance while retaining the ability to handle relational data with SQL capabilities. QuestDB supports both SQL and NoSQL-like functionalities, providing users with flexibility in their data modeling and querying approaches. The database consists of multiple components, including the ingestion engine, storage engine, and query engine, working together to ensure high-performance data ingestion and retrieval.

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MongoDB Features

Flexible Data Model

MongoDB’s schema-less data model allows for the storage and querying of diverse data types, making it well-suited for handling complex and evolving data structures.

High Availability

MongoDB’s replica set feature ensures high availability through automatic failover and data redundancy.

Horizontal Scalability

MongoDB’s sharded cluster architecture enables horizontal scaling and load balancing, allowing it to handle large-scale data processing and querying.

QuestDB Features

High-Performance Ingestion

QuestDB is optimized for high throughput ingestion, allowing users to efficiently ingest large volumes of time series data at high speeds.

Fast SQL Queries

QuestDB provides fast SQL queries for analyzing time series data. It extends the SQL language with time series-specific functionalities to assist with real-time analytics.

Operational Simplicity

QuestDB aims to provide a user-friendly experience with operational simplicity. It supports schema-agnostic ingestion using popular protocols such as InfluxDB line protocol and PostgreSQL wire protocol. Additionally, a REST API is available for bulk imports and exports, simplifying data management tasks.


MongoDB Use Cases

Content Management Systems

MongoDB’s flexible data model makes it an ideal choice for content management systems, which often require the ability to store and manage diverse content types, such as articles, images, and videos. The schema-less nature of MongoDB allows for easy adaptation to changing content structures and requirements.

IoT Data Storage and Analytics

MongoDB’s support for high data volumes and horizontal scalability makes it suitable for storing and processing data generated by IoT devices, such as sensor readings and device logs. Its ability to index and query data efficiently allows for real-time analytics and monitoring of IoT devices.

E-commerce Platforms

MongoDB’s flexibility and performance features make it an excellent choice for e-commerce platforms, where diverse product information, customer data, and transaction records need to be stored and queried efficiently. The flexible data model enables easy adaptation to changes in product attributes and customer preferences, while the high availability and scalability features ensure a smooth and responsive user experience.

QuestDB Use Cases

Financial Market Data

QuestDB is well-suited for managing and analyzing financial market data. Its high-performance ingestion and fast SQL queries enable efficient processing and analysis of large volumes of market data in real time.

Application Metrics

QuestDB can be used for collecting and analyzing application metrics. Its ability to handle high data throughput and provide real-time analytics capabilities makes it suitable for monitoring and analyzing performance metrics, logs, and other application-related data.

IoT Data Analysis

QuestDB’s high-performance ingestion and time series analytics capabilities make it a valuable tool for analyzing IoT sensor data.


MongoDB Pricing Model

MongoDB offers various pricing options, including a free, open-source Community Edition and a commercial Enterprise Edition, which includes advanced features, management tools, and support. MongoDB Inc. also offers a fully managed cloud-based database-as-a-service, MongoDB Atlas, with a pay-as-you-go pricing model based on storage, data transfer, and compute resources. MongoDB Atlas offers a free tier with limited resources for users who want to try the service without incurring costs.

QuestDB Pricing Model

QuestDB is an open-source project released under the Apache 2 License. It is freely available for usage and does not require any licensing fees. Users can access the source code on GitHub and deploy QuestDB on their own infrastructure without incurring direct costs. QuestDB also offers a managed cloud service.