> David: I can do you one better. Another example. Amazon.com used Oracle databases when it was started. Amazon.com did not finish their migration off of Oracle databases and onto AWS products until 2019.
> Ben: Oh, my God.
> David: Thirteen years after AWS launched.
> Ben: That is insane.
> David: It took that long for Amazon itself to migrate off of Oracle.
(a) a lot of Amazon's software was so old that it connected directly to the databases. We had to finish all of the SOA migrations that were long overdo -- all the misc random tools no one had gotten around to migrating -- before we could even contemplate moving off Oracle.
(b) it wasn't done as a simple port; instead, the systems were re-architected in the process to no longer share backing databases as at all, which basically meant it needed a complete rewrite, which took a long time to get funded and then a long time to deliver.
It seems AWS made the right trade offs when it was starting, given its current position. The proof is in the pudding.