- Vasilis Vontikakis
If you have a VPS, at some point you will have to make the upgrade from mysql 5.5 to 5.6. However the upgrade may fail if your VPS doesn't have more than 500MB of RAM or your all your free RAM resources are less than 400MB.
The reason is that mysql 5.6 needs to allocate 400MB additional RAM, because it has activated by default the mysql performance schema. This schema records statistics from the mysql database in runtime. Its main usage is to help the database administrator to check really low level measurements and identify performance issues like slow queries due to InnoDb locks, ...