My little business uses PG. Had a unique need for PK IDs. It was pretty easy to make a little extension in C to generate them for us, and linking in PG was super easy (but the .so has to be on replica before loading) and we only used the TEXT type cause I didn't want to figure out making a new 128bit data-type. But can't do this in RDS.
Postgres has all sorts of great stories for customisation. It does custom aggregates better than MySQL or SQL Server, for example, because you can just write them in SQL with not hassle.
Storing data is the most universal task in the software ecosystem. Data storage will be confronted as a problem by everyone even tangentially related to software - the Truly Inspired Software Engineer, the Almost Incompetent Software Engineer, the Developer, the Manager, the Lawyers. The Customers will care, sooner or later it becomes their problem. The Subcontractors care. Even the Government cares about data storage.<p>It is a not a problem where 'unique' or 'customised' are competitive advantages. 'Boring', 'available', 'reliable' and 'well understood' are competitive advantages. Relational databases are a great way to store small quantities of arbitrary data and PostgreSQL is a textbook relational database.
I don't think I can get any extensions loaded if I use RDS. They've basically handicapped what I'm reading is one of the most useful features of postgres
If RDS won't support the extension, it might as well not exist. Well, almost might as well. I'm lucky I don't need sfcgal but if I did I might give up on RDS.