After MySQL 5.1 was released work started on MySQL 5.2, but then
this was renamed to MySQL 6.0. There were many new features
introduced in 6.0. But then stabilizing this branch became as
huge task. Eventually the decision was made to start of with a
stable branch and backport the new features from 6.0. This is how
many of the 6.0 features landed in 5.5 and 5.6.
So let's see which features 6.0 brought and were they landed. I'll use the What Is New in MySQL 6.0 section of the …