NoSQL databases might be a tougher choice than relational ones when your schema changes a lot and those changes need to be applied consistently across all your data. Relational databases, with their strict schemas, are built to handle these kinds of updates in a more controlled way. You know exactly what you're getting. With NoSQL, especially document or key-value stores, schema evolution can mean more manual work and a higher chance of data inconsistencies if you're not super careful. It's like, you get a lot of flexibility up front, but then you pay for it later when things need to change in a big way.

Everyone says NoSQL databases are awesome for flexible schemas, perfect for data models that change all the time. But, honestly, I've been in spots where changing a NoSQL schema felt way harder than just messing with a relational table. Like, say you have these super nested documents and suddenly you need to add a new rule or a required field deep down in there for millions of documents. That can be a giant project to move everything over. With a relational database, you could just add a column that allows nulls and fill it in later. What have your experiences been like? When does NoSQL's schema flexibility actually become a problem, and when do you just stick with a relational database, even if you don't know the whole schema from the start?