[shantly]

IMO if your data model's still so nebulous that you're changing it so often that SQL migrations are a serious impediment to progress, you probably don't need any real datastore yet. You can usually figure out WTF you're going to do, broadly speaking, before persisting anything to a remote database. And if you can, you very much should.

Yes, yes, there are sometimes exceptions, one must repeat explicitly despite having already said it (see: "probably") because this is HN.

[asdfman123]

Can someone explain to me any circumstances where having no well defined data model is better than coming up with a clear relational model? Honest question. It seems like it would just be a huge hassle trying to deal with your dissimilar data.

When I'm designing an app from scratch I often think about the SQL tables first and how I'm going to build them, and it really sharpens my idea of what my program will be.

I don't see how skipping that process would make things easier.

[noobiemcfoob]

I've built IoT platforms where data from any device must be accepted. This is largely where my preference for NoSQL comes from. A device created tomorrow will not have a schema I can predict or control. NoSQL allows the easy integration of that device while a traditional database will at worst require a migration for each new device you want to support.

[asdfman123]

Please correct me if I'm wrong, but that sounds like a very narrow use case, and also something that could be solved by simply stuffing JSON into a RDBMS.

However, perhaps there are tools that NoSQL provides that are handy.

[noobiemcfoob]

What's wrong is that you asked for any usecase and then critique one because it's not broad enough for you.

[asdfman123]

Sorry, I'm not trying to be argumentative, I just argue in order to understand better.

[noobiemcfoob]

Then argue honestly and work to steelman other's arguments. To address your point, I'd hardly consider IoT platforms to be a "narrow" usecase. Smaller than the whole of computing, surely, but it's a growing field. The reality is that more and more devices will become available that generate all sorts of hard to predict data. Being able to handle those easily will be a large strength for platforms going forward. Dropping this hard to predict data as JSON into a RDMS will certainly come back to haunt you in 5 years.

[Scarbutt]

You can't really design your tables well enough without knowing your UI, its a back and forth, forth and back process.

[asdfman123]

And it's something you can do entirely on paper, too, before you go to code.

However I've never greenfielded an actually large application.

[shantly]

How does UI inform table design?

[Scarbutt]

It will give you lots of insight when planning your data models/tables.