I am far from being a database expert, I just know enough basics to query what I need, so feel free to correct/complete the following:
- Mongo has been built to store json objects -> Yes, but from what I understand benchmarks indicate that PostgreSQL is faster at reading/storing/indexing json/jsonb content. I don't think that it is good reason to use it.
- Mongo is schemaless -> There might be some usecases, but I bet in most cases this problem can be worked around. Especially in a database with JSONB support.
- MongoDB horizontal scaling is way easier than PostgreSQL. Yes, it seems that scaling horizontally Mongo is extremely easy compared to any other relational database.
And ... that's it. But there is probably more.
At the moment, here's how I would summarize MongoDB benefits if asked my opinion when starting a project:
- For a small projects or a prototype: ease of use, ease of configuration, don't require too much thinking into my data model while I am experimenting
- For a bigger project: horizontal scaling should be easier
Does that sound accurate to you? Am I missing anything important?