So far the features that oracle had that people have mentioned:
- An amazing query optimizer
- Replication (enabling High Availability) features available 15 years ago
- Oracle was the only database able to take multi GB or TB of data in a single table/DB. (Old MySQL/Postgre had various limitations like X GB per table for a long time, they still do).
If you worked in the DB in the 200X years, Oracle was the standard and for good reasons. MySQL/Postgre were considered like toys, for good reasons.
I understand what you're saying to mean simply replication, NOT a proper distributed database system allowing/facilitating writes using what we now know to be state-of-the-art theorems/methods. To rephrase, I assume you mean oracle dbs let people write to one database, and send updates to some mirrors somewhere else.
Just google it for yourself. This is a forum, not every post needs to be a peer-reviewed scientific paper. If you don't believe the OP then go ahead, but getting him/her to jump through hoops to try to prove a point is dumb.
However, as the creator of [citation needed], I'd just like to say: if you want to say something in a forum, and it seems wrong, then I for one welcome data that backs up the assertion. Why should we take any one on face value?
You're absolutely right in that the OP has no obligation to 'jump through hoops' to prove their point (and again they are free to not reply), but people on HN generally don't make claims without at least some citation/proof, and that's why (to me, and I'm sure others) HN is valuable. Everyone has opinions. The expectation on HN is usually of reasoned discourse, and fact-driven analysis (where applicable)... While this is a minor inconvenience for posters/community members, it does a whole lot to solidify HN as a worthwhile place for people who care about that kind of thing to hang out.
Could you put into words a little bit more of what the Oracle DB does that Maria/MySQL/Postgres could not?