Welcome!! ^.^

No issues whatsoever. Phoenix is the back-end, html/css/bootstrap/whatever is all front-end, entirely distinct.

If you use PostgreSQL as your database it has a FANTASTIC GIS extention pre-included, it could probably do your queries faster than about anything else. And postgresql is the default supported database in a new phoenix project too.

Functional Programming just means putting functions first, they are first-class values and can be passed around like anything else. The big thing that helps prevent ‘issues’ in my opinion is immutability (Elixir is) and static strong type system (Dialyzer helps here, I always recommend using it via the Dialyxir plugin). Testing is always good to do regardless, and Elixir makes testing a wonderful breeze with integrated doctests.

The fact is that PostgreSQL is probably the most advanced database out, including not just SQL but also NoSQL’s in various styles, a very powerful search database functionality, many many extensions, FDW’s (Foreign Data Wrappers that let you access ‘another’ database from inside PostgreSQL all through the same interface) and much much more, in addition to it is entirely free, open source, blazing fast, and included in every linux distribution in existence’s repo’s as well as being trivial to install on Windows while being one of the most ANSI SQL compliant databases out.

That all depends on what you are making, how it will be accessed, etc… Biggest word of note, keep your functions that ‘do’ stuff in their own modules, do not mix up ‘doing’ stuff in your web-related modules, makes it hard to refactor and/or pull apart or interact with in other ways later.