For those of you that have clients with very large MySql databases, they won't be able to export them via PhpMyAdmin after upgrading to Plesk version 8.3. I was alerted of this today when one of my clients tried to export one of their large DB's.

The symptoms:
When you try to export a large database to a file you will receive a file of 0 bytes in size in return. Also when you try to export it via plain text in the browser you will get a blank page, or plesk will stop responding all together.

The Solution:
1. Open your plesk php.ini -- not your regular php.ini but the one used by Plesk (usually located at: /usr/local/psa/admin/conf/php.ini) depending on your install.
2. Find memory_limit and change it to: memory_limit = 256M
3. Stop and start psa services via SSH: service psa stopall then service psa start

Original thanks for this fix goes to user "lavinya" on the plesk forums. I thought it would be handy here too, if anyone runs into this problem.

While this method does work, there are many other implications that are involved in which you may not want to do this. If you are hosting a single site or just don't have very many hosts then the above mentioned method is just fine. However if you are hosting a heavy traffic site, or many sites relying on PHP that you can have an abusive user / script run the server load to all new highs. The preferred method for large databases are to upload the file.sql with ftp. Use PHPMyAdmin to create a MySQL user and blank database and then load the database from command line:

mysql -u username -p databasename < dbbackup.sql