Oracle is everything you'd ever need in a truly enterprise class database engine. Distributed databases, replication, scalability to hundreds of processors, and a library of built in functions and add on widgets to make even the most jaded dba slaver in anticipation.
It's also quirky, (what database isn't) and not cheap. But if you need that kind of scalability, there are only a few other options, like some of the lesser known databases from siemens or db2 from IBM.
Postgresql is squarely in the mid-range class compared to those systems. It has a couple of replication projects in the work that are showing promise, but it can't run in clusters, and likely wouldn't scale to 128 processors on an ultra sparce.
But it does have all the basics of a real database system, like stored procedures, triggers, foreign keys, indexing, MVCC (Multi-Version concurrency control. Look it up in the docs, it's a quite nice system of auto-locking) etc. etc...
It's also gotten quite fast in the last few years, and it is ultra stable when run on ultra stable hardware.
