Possible to implement a manual increment with just simple SQL INSERT?

Question

I have a primary key that I don\'t want to auto increment (for various reasons) and so I\'m looking for a way to simply increment that field when I INSERT. By simply, I mean

Answer 1

How about creating a separate table to maintain the counter? It has better performance than MAX(id), as it will be O(1). MAX(id) is at best O(lgn) depending on the implementation.

And then when you need to insert, simply lock the counter table for reading the counter and increment the counter. Then you can release the lock and insert to your table with the incremented counter value.