I think parent and GP both have an element of truth, but that the ultimate situation is more nuanced than either suggests. Customer demand is likely the biggest

I think parent and GP both have an element of truth, but that the ultimate situation is more nuanced than either suggests. Customer demand is likely the biggest factor, but I'd be surprised if Oracle managed an exclusivity deal on RDS. Of the major RDBMS players, Oracle, for all their weirdness, all their proprietary functionality, all the damn-the-relational-model-here's-your-physical-row-identifiers, is a pretty logical choice as the first commercial offering.