MySQL ... doesn't scale so well

We're getting WAY off topic here, but I don't think that is at all true. I'm not sure what you mean by scale - concurrent users / queries / whatever, but we're currently putting over 2000+ queries per second through a 500+ tables MySQL set-up - and that's a mix of INSERT/UPDATE/SELECTs - not just SELECTs....

The trick is to not write SELECTs that take a long time to run (measured in hundredths of seconds!) on tables that also need updated or inserted into.

Taking a schema which works on Oracle or whatever, and trying to port it to MySQL will fail. Designing to MySQLs strengths and using them to build a large system is however very possible.

To bring this back on topic slightly, I treat statements like "you can't build a full-blown application with MySQL" just as I treat "you can't build a full-blown application with Perl"...

Tony