[fdr]

> But when it comes to building spacial indexes on hierarchical dimensions, or whatever, Postgres just isn’t going to have a feature for that. I’ll have to figure that one out for myself.

In this case, yes it is, Postgres probably has the best type system and extensibility of all SQL databases. GiST and GIN are very good technologies that also exist in Informix.

If I had to choose something that is missing in Postgres and very far away for sheer want of implementation effort, it's parallel execution of queries.

Oracle RAC is also quite a crazy and neat feature, except when it has problems, in which case you get even more crazy for that crazy.

On the other hand, Oracle is also not a strict superset of the features in PostgreSQL. For example, 9.1 has the only credibly fast implementation of SERIALIZABLE level isolation that I am aware of. There are also interesting features like "index exclusion constraints" that have no equivalent in Oracle, and solve problems hard to solve otherwise (example constraint: there are no overlapping circles in this table)