DDL (Data Definition Language) statements create, alter, and remove database objects. These types of changes can be a very dangerous action to take on such a critical piece of your infrastructure. You want to make sure that the command that you are executing has been given proper thought and testing.
In this post I go through multiple version of MySQL and verify the best course of action to take in regards to executing DDL statements. There are many things that you have to consider when making these types of changes, such as disk space, load on the database server, slave replication, the type of DDL statement you are executing, and if it will lock the table.
Because of these risks, there are tools that can be used to help mitigate some of the dangers. But unless you have tested and verified their functionality, these tools in themselves can cause trouble. Whenever in doubt, take the time to test …[Read more]