About MySQL development (Optimizer mainly)

There are great features in MySQL 5.6. But not only that. We also tried to correct some old behaviors and limitations which, over the years, have shown to irritate our Community. The behavior of TIMESTAMP columns is one of them. My colleague Martin Hansson did most of the work and summarized it well in his blog . Thanks to him, since MySQL 5.6.5, it's possible to declare more than one TIMESTAMP column with the DEFAULT CURRENT_TIMESTAMP or ON UPDATE CURRENT_TIMESTAMP attributes. And it's possible to have DATETIME columns with such attributes. Two limitations lifted! But that is not the end of the story. TIMESTAMP was still special. Unlike other datatypes, if not declared with the NULL or NOT NULL attributes, it would automatically get NOT NULL. And the first TIMESTAMP column of the table would automatically get DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP. Many people found these behaviors odd. For them, my colleague Gopal Shankar added a new option to the server, d...