> It's not clear to me that it really can do that, though.
It would seem exceedingly foolhardy to put all your eggs into, what is essentially a compatibility shim layer/plugin, that may or may not actually be compatible with Oracle or all of Oracle.
The company behind it also is an unknown (to me at least) - HiGo[1].
So, IvorySQL is FOSS and free (as in beer) - but what happens if some feature doesn't actually work like advertised? Or something isn't implemented yet? Now you're paying HiGo for support instead of Oracle - although I'd trust Oracle's product a lot more personally.
> I'd ask why you are paying for any commercial DB in that case.
People pay for commercial DB's for a lot of reasons - including having someone to call at 3am when things go bad. Look at how prevalent SQL Server is - most of the deployments I've seen are because the company simply decided they will use SQL Server for everything (ie, not a technical reason).
[1] https://www.highgo.ca/
