[happimess]

> There is need to iterate and adapt frequently, sometimes as part of your go-to-market strategy, in order to fully understand the problem space.

If you're pivoting so hard that your SQL schema breaks, how is a schemaless system going to help you? You'll still have to either throw out your old data (easy in both cases) or figure out a way to map old records onto new semantics (hard in both cases).

I agree with GP that this is a central problem to solve, not something to figure out _after_ you write software. Build your house on stone.

[spmurrayzzz]

>If you're pivoting so hard that your SQL schema breaks, how is a schemaless system going to help you? You'll still have to either throw out your old data (easy in both cases) or figure out a way to map old records onto new semantics (hard in both cases).

I agree with your comment that it's a central problem to solve and that both options, throwing out data or map old records onto new semantics, is an endemic choice both stacks need to make. I don't agree that it's always possible to solve entirely up front though.

In my experience, it has been less so about whether the storage engine is schemaless or not, even many modern nosql stacks now ship with schemas (e.g. MongoDB). I think the differentiation I make between these platforms is mostly around APIs. Expressive, flexible semantics that (in theory) let you move quickly.

As an aside, I also think the differentiation between all these systems is largely unimpactful for most software engineers. And the choice often made is one of qualitative/subjective analysis of dev ergonomics etc. At scale there are certainly implementation details that begin to disproportionately impact the way you write software, sometimes prohibitively so, but most folks aren't in that territory.

[funcDropShadow]

Admittedly, my experience with MongoDB and Cassandra has gained some rust over the last decade, but what makes you say such nosql databases have expressive APIs? Compared to PostgreSQL they have miniscule query languages and it is very hard, if at all possible, to express constraints. And constraints, sometimes self-imposed sometimes not, are what makes projects successful, even startups. Many startups try to find this one little niche they can dominate. That is a self-imposed constraint. People tend to think freedom makes them creative, productive, and inventive, while in fact the opposite is the truth. With opposite of freedom I mean carefully selected constraints not oppression.