What problems can arise if php mysql client doesn't match the mysql server version?

Question

I have two installations of mysql server 5.1.32 and 5.0.77 (same machine, os x leopard). My php mysql extension is compiled against 5.0.77 (that was the easiest thing to do, and I did it after installing 5.1.32). I'm using the 5.1.32 installation since that's what I compiled my python MySQLdb extension against. I don't code in php much if ever. My main use of the php installation is phpmyadmin. phpmyadmin works in this way against the 5.1.32 mysql server but shows a warning:

"Your PHP MySQL library version 5.0.77 differs from your MySQL server version 5.1.32. This may cause unpredictable behavior.".

My question. Can I expect any serious problems from phpmyadmin with this kind of setup?

I'm using the latest version of phpmyadmin, and it connects thru a tcp connection (not socket file).

Answer 1

You shouldn't have any problems, all the queries are sent over TCP, they are all pretty much standard.

I think the only bad thing is that you can't use ceratin features.

Answer 2

If the developers are respectable, using an older client version on a newer server version shouldn't ever cause issues with any software.

Using a newer client version with an older server version may cause issues depending on the developers policies.

Answer 3

You should be ok however some functions/bugs/quirks could differ between the two versions. I would recommend looking at the MySQL's changelog from version 5.0.77 up to (and past if you have time) 5.1.32.

There was an issue with MySQL user's passwords stored between a version of MySQL 4.11 and up connecting to a version lower than that. Since you're this far I'm sure that's not it. For reference it was an easy fix involving updating the user's password with OLD_PASSWORD().