We have a bunch of PHP-5.3/Apache servers connecting to some MySQL-5.0 servers, and we'd like to plan the transition to MySQL-5.1.
On the PHP servers there is customer's stuff (mostly the usual floss products like joomla, wordpress, and so on). I'm thinking about upgrading the Apache/PHP part to the MySQL-5.1 client libs and still keep the server side to MySQL-5.0 for a while.
I did some googling and some RTFM'ing but didn't find much: is it asking for troubles or there is perfect compatibility when using mysql-5.1 client libraries to connect to 5.0 servers? Of course I'm talking about the latest stable releases of the two branches and not some older version.
I don't think there should be any problem.
Client server talk on a protocol. Protocol is not something that changes frequently. Beside this, its a 5.0 to 5.1 communication. Not a major version difference. Just a minor one. So it should work. Higher version-ed client should always be able to communicate with lower version-ed server. But vice versa is not possible.