It's easy to start a bicycle rolling down a steep hill too. It's only later that you find out whether the brakes, tires and handling characteristics are up to par...

> features that "dbms experts wanted"

Maybe they want those features because the know what they're doing, and think some of those features are pretty critical.

[1] - http://gigaom.com/2011/12/06/facebook-shares-some-secrets-on...

Prior to version 5+, I'd have called it unusable as the lack of real foreign key constraints (for instance) was simply unacceptable for real applications. The argument (by NoSQL proponents too) that the application has to check data constraints anyway might be true, but ending up with dirty data is the worst possible outcome. Check it in both the application and the database if you can.

no check constraints

views with aggregates are too slow to be used

no expression indexes

triggers don't fire on cascaded actions

no window functions

can't set default values to be the result of a function

no transactional DDL

doesn't have multiple databases, just schemas misnamed as databases

rollbacks are orders of magnitude slower than other RDBMS, and it is interrupted it can corrupt the database

functions can't use prepare/execute, so no dynamic SQL in functions

subqueries are broken: can't modify and select from the same table

functions can't be called recursively (seriously? is this 1962?)

triggers can't alter the table they are firing against

stored procedures can't be invoked from prepare/execute

"slow query" log has a completely useless resolution of seconds