# Emerging Industrial Internet of Things Open-Source Platforms and Applications in Diverse Sectors
## 4 Open-Source Edge IoT platforms
### Overview of Open-Source Databases
#### 4.1.1 Examples  
MySQL is a popular open-source RDBMS that is utilized for internet use cases [51]. It is regarded as one of the most widely used, and it globally boasts a substantial community of developers and users. It has the capability to be seamlessly incorporated with a range of computer languages, including PHP, Java, and Python, hence facilitating the development of applications employing these languages [51]. MySQL adheres to ACID principles, ensuring integrity and reliability [51]. MySQL is compatible with multiple platforms such as Linux, Windows, and macOS, allowing for flexible deployment choices [51]. MySQL enjoys extensive support and boasts a substantial community of developers, offering a plethora of tools and assistance. MySQL exhibits exceptional scalability, enabling it to effortlessly manage substantial amounts of data and accommodate heavy traffic loads. Configuring and managing MySQL can be difficult, especially for deployments on a large scale. MySQL does not possess certain sophisticated capabilities, such as built-in support for JSON and functionality for graph databases. PostgreSQL, or Postgre, is an open-source RDBMS renowned for its sophisticated capabilities and strong adherence to SQL standards [52]. PostgreSQL is a robust and versatile database management system that offers a broad range of data types and extensive functionalities. Configuring and managing PostgreSQL, especially for large-scale deployments, can be intricate. MongoDB offers exceptional performance and scalability, enabling horizontal scaling through the distribution of data across several servers [53]. MongoDB offers automated sharding and replication, simplifying the process of scaling and ensuring continuous availability. The MongoDB Change Data Capture (CDC) function is an essential component that allows for capturing real-time changes, hence boosting the overall capabilities of the system. Redis is a freely available, memory-based data storage system that operates on a key-value model [54; 55]. It can serve as a database, cache, or message broker. Redis lacks the capability to handle intricate queries similar to those supported through conventional SQL databases. Efficient operation of Redis, especially in large-scale deployments, may necessitate additional resources [54; 55]. Apache Cassandra is a freely available distributed NoSQL database specifically engineered to provide exceptional availability, scalability, and performance [56]. This technology is especially well suited to applications that necessitate rapid processing and the retrieval of vast quantities of data. Apache Cassandra is a decentralized database that can efficiently manage enormous volumes of data across numerous nodes. The system offers a versatile data model that accommodates various data structures such as wide columns, documents, and key-value pairs [56]. Apache Cassandra provides robustness and resilience by employing a masterless architecture, enabling the uninterrupted operation of nodes even in the event of node failures. MariaDB is a widely used open-source RDBMS that was specifically built to be compatible with MySQL. The system offers assistance for a range of query types, encompassing SELECT, INSERT, UPDATE, and DELETE statements [57]. InfluxDB offers exceptional performance and scalability, enabling developers to efficiently manage extensive datasets in real time. InfluxDB's capability may be constrained in comparison to other database systems due to its specialized design for time-series data [58]. Due to its emphasis on high-precision timestamps, this database system may necessitate a greater allocation of resources in comparison to other systems. Elasticsearch's emphasis on real-time search and analytics may necessitate a higher allocation of resources compared to other database systems. Elasticsearch's capability may be constrained in comparison to other database systems, as it is purposefully tailored to search and analytics purposes [59].