This brings me back to the recent discussion about reading other people's code: it is almost certainly smarter to extend an existing database until it's capable of meeting your needs, rather than write one from scratch.
The fact that many programmers don't see it that way is a testament to their irrational fear of diving into other people's code.
People need to stop acting like PostgreSQL is some holy grail database. It isn't.
And making a solid, featureful, and performant database is vastly harder.