max_allowed_packet is the maximum size of a single SQL statement.
It's a setting on the server, as well as for the mysql command line
interface.
See http://dev.mysql.com/doc/refman/5.0/en/packet-too-large.html
I think 1 MB is the default; the maximum setting for MySQL 5 is 1 GB.
You can adjust
When a query exceeds the size of the maximum allowed packet, mysqld closes
the connection. It assumes something has gone wrong with the client. There
are two max_allowed_packet variables, one for the server and one for the
client. This is documented in section A.2.9 of the documentation
