Hi!

My 3 VPSs are running on MySQL 4.xx and I have several customers on them.

I have a script that uses nested queries so I think I need to upgrade one server to MySQL 5.

Do you think upgrading one server to MySQL 5 through cPanel could damage my customers databases? What is the level risk?

I would appreciate any opinions and tips.

Thank you!

If it is only a small number of databases, I would not worry too much about it. If you want to be paranoid, run a database repair on all the databases before you start the process and shut down mysqld before you make the transition.

Your databases will have to be converted to MySQL 5 databases in the process (which is not easily reversible) though, which is what they warn you about regarding upgrading. However, if you only have a small number of databases it shouldn't be too hard to back them all up before you begin the process, JUST in case.

Thank you for your help

There would be some script client problems which you will need to solve. However it is suggested to search the mysql.org for upgrade tutorials specifying your exact mysql versions

You need to be careful about the following:

1. non-latin character encodings, these will cause problems when upgrading to 5.x

2. some programs may not work due to the change in the way join queries are written in 5 (4images is one that I know of that has this problem).

database Authentication errors will be common issue while upgrading to mysql5 which can be fixed by selection support old version passwords from Tweak settings. We didn't had any problems while upgrading from 4 standard to 5.