When working with raw JSON data in Eventhouse, one common challenge is comparing two records to identify what changed—especially when the structure isn’t fixed. Fields may appear, disappear, or shift in type, making traditional column-based comparisons brittle or outright impossible. This post will walk you through how to compare two JSON arrays and find what changed without needing to define the schema first. 

So, you’ve started exploring real-time intelligence in Fabric and maybe even followed the Microsoft tutorial to implement a real-time solution. Now, you’re looking to analyze and visualize that data, and that’s where KQL (Kusto Query Language) comes in.

When I started, I struggled a bit, so I thought it would be a good idea to provide some basic queries (and explain what they do) for people who want to get started but are unfamiliar with querying data.