[H2 and Firebird]auto_increment, identity or trigger plus generator?

[randywhite]

in Firebird the only way to have an auto increment coloumn is to setup a generator and use it with a trigger.In H2 db there are auto_increment and identity keywords to do it.What is the best way?Mysql use auto_increment too, but there is some problems with cuncurrence read and table lock, isn't true?Thank you.