By default, Amarok use SQLite to store collection informations. If you’ve a running MySQL or Postgre server on your machine, you can optimize Amarok collection indexing reducing retrieval time.

1. Open a root shell (sudo bash) and run mysql

   mysql> create database amarok;
   Query OK, 1 row affected (0.00 sec)
   
   mysql> grant all privileges on amarok.* to 'amarok'@'localhost'\ 
   identified by 'type_here_your_password';
   Query OK, 0 rows affected (0.00 sec)

2. Open Amarok and go to Settings > Amarok configuration > Collection and fill the database fields (watch screenshow)
3. If you got an error don’t worry, simply force collection re-scan (Tools)

Now your music collection run on an efficient MySQL database.