How to Receive Real-Time Events in C# from MySQL Database Changes

Описание: Discover effective methods for receiving real-time notifications in C# when MySQL database records are inserted, deleted, or modified. Read on to learn about the best solutions!
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This video is based on the question https://stackoverflow.com/q/75365033/ asked by the user 'Francisco Lopez' ( https://stackoverflow.com/u/19641462/ ) and on the answer https://stackoverflow.com/a/75365342/ provided by the user 'Bill Karwin' ( https://stackoverflow.com/u/20860/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

As a developer utilizing C# for your WPF.Net applications, you may encounter situations where it's critical to monitor changes in your MySQL database. Specifically, you might need to know when records are inserted, deleted, or modified. This is a common challenge, and there are multiple methods to approach it. In this post, we'll explore the practical solutions available to achieve real-time event notifications from a MySQL database.

Understanding the Problem

In many applications, knowing when data changes in a database is crucial for ensuring data integrity and user experience. While there are several ways to monitor changes, each method has its own set of advantages and disadvantages.

Common Methods to Monitor Database Changes

Polling

Change Data Capture

Triggers

Let’s delve into each of these methods, assess their effectiveness, and discuss the best solution for your application needs.

1. Polling

Polling is a straightforward approach where your application queries the database at regular intervals to check for changes.

Pros

Simple implementation: Easy to set up and doesn't require extensive changes to your current architecture.

Cons

Resource-intensive: Continuous polling can lead to heavy loads on your database, especially if many clients are polling simultaneously.

Delayed notifications: Since the polling interval can vary, there may be a substantial delay before changes are detected.

Conclusion

Polling is not the most efficient method, especially for high-traffic applications. It's more suitable for simple applications where real-time updates are not essential.

2. Change Data Capture

Change Data Capture (CDC) leverages MySQL’s binary log to monitor changes. This log records all transactions on the database.

Pros

Captures all changes: Provides a comprehensive history of all changes, making it possible to track multiple transactions.

Cons

Complexity: Requires additional tools (like Debezium) or the creation of a custom binlog tail client, which can be a significant undertaking.

Overhead: Filtering the necessary changes from the logs can add to the complexity and resource requirements.

Conclusion

CDC can be effective but involves a steeper learning curve and additional resource demands, meaning it's more suitable for larger, data-driven applications.

3. Triggers

Another method is to use database triggers, which execute a function when a specific change occurs in the database.

Pros

Immediate notification: Triggers respond instantly upon data modification.

Cons

Timing issues: Notifications might be sent before transactions are committed, leading to inconsistencies.

MySQL limitations: Using UDFs (User Defined Functions) to send notifications may require additional installations and configurations.

Conclusion

While triggers can immediately notify you of changes, the risk of inconsistencies makes them less reliable for applications needing precise real-time updates.

Recommended Solution: Message Queue

The most effective solution for monitoring database changes in real-time is implementing a message queue. After your application commits changes to the database, it publishes a message to the queue, and other clients can subscribe to receive notifications.

Benefits

Decoupled architecture: Helps you isolate the application logic from database changes, enhancing scalability and maintainability.

Efficient resource utilization: Reduces the database load compared to polling.

Real-time notifications: Clients receive updates immediately upon data changes.

Implementation Overview

Implementing a message queue typically involves:

Selecting a message queue system (