My client is looking to build an ecommerce site but wants Oracle as the backend (to handle the entire business from end to end, not just the webapp part) because he's been told that MySQL (and MS Access) will choke when the numbers start rising. I'm not a database expert, can someone tell me whether this statement is valid? Below are the client's points:

'Iíve had two unrelated IT experts that I trust generally, both tell me that I need Oracle after Iíve described in detail the complexity and scalability I need. Within a few years we expect to be processing 100,000 orders per year, buying and analyzing hundreds of thousands of dollars in Google Adwords, etc. Iíve been told that MS Access or MySQL will choke when we scale up.'

Thanks in advance,