Q: With MySQL, when attaching a file, I got 
   java.lang.IllegalArgumentException:
   Packet is larger than max_allowed_packet from server configuration of 1048576 bytes

A: This happens when the file you are trying to attach has a size larger than the 
   max packet size of your mysql server (the default is 1M). To solve this problem,
   in mysql's configuration file (my.cnf), under [mysqld], add   
   set-variable  = max_allowed_packet=12M 

   Note that, after the modification, you need restart mysqld as well as your
   servlet engine.

   You may also see a similar java.sql.SQLException: 
   Communication link failure: com.mysql.jdbc.PacketTooBigException