This used to be a strong distinguishing feature, but postgresql has it too as of 8.4, albeit in a somewhat different form (SQL standard "with recursive"; if you

This used to be a strong distinguishing feature, but postgresql has it too as of 8.4, albeit in a somewhat different form (SQL standard "with recursive"; if you want the Oracle "start with ... connect by" syntax, you have to get the EnterpriseDB commercial postgresql fork). Oracle still has features that I don't know where to find in the mainstream open-source competition: among others, support for encrypted on-disk storage, and multi-master write support (as opposed to write-on-master, read-from-mirrors). But a lot of those require an "Enterprise" license, which costs significantly more than the already high license fees for the "standard" edition. (Besides which, if you're building a cluster, you probably want enough control over the physical I/O hardware, for performance reasons, that it doesn't make sense to build it on AWS.)