(mysql.info.gz) Packet too large

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 A.2.9 `Packet too large'
 ------------------------
 
 A communication packet is a single SQL statement sent to the MySQL
 server or a single row that is sent to the client.
 
 In MySQL 3.23, the largest possible packet is 16MB, due to limits in the
 client/server protocol. In MySQL 4.0.1 and up, the limit is 1GB.
 
 When a MySQL client or the `mysqld' server receives a packet bigger
 than `max_allowed_packet' bytes, it issues a `Packet too large' error
 and closes the connection.  With some clients, you may also get a `Lost
 connection to MySQL server during query' error if the communication
 packet is too large.
 
 Both the client and the server have their own `max_allowed_packet'
 variable, so if you want to handle big packets, you must increase this
 variable both in the client and in the server.
 
 If you are using the `mysql' client program, its default
 `max_allowed_packet' variable is 16MB. That is also the maximum value
 before MySQL 4.0. To set a larger value from 4.0 on, start `mysql' like
 this:
 
      mysql> mysql --max_allowed_packet=32M
 
 That sets the packet size to 32MB.
 
 The server's default `max_allowed_packet' value is 1MB. You can increase
 this if the server needs to handle big queries (for example, if you are
 working with big `BLOB' columns).  For example, to set the variable to
 16MB, start the server like this:
 
      mysql> mysqld --max_allowed_packet=16M
 
 Before MySQL 4.0, use this syntax instead:
 
      mysql> mysqld --set-variable=max_allowed_packet=16M
 
 You can also use an option file to set `max_allowed_packet'.  For
 example, to set the size for the server to 16MB, add the following
 lines in an option file:
 
      [mysqld]
      max_allowed_packet=16M
 
 Before MySQL 4.0, use this syntax instead:
 
      [mysqld]
      set-variable = max_allowed_packet=16M
 
 It's safe to increase the value of this variable because the extra
 memory is allocated only when needed.  For example, `mysqld' allocates
 more memory only when you issue a long query or when `mysqld' must
 return a large result row.  The small default value of the variable is a
 precaution to catch incorrect packets between the client and server and
 also to ensure that you don't run out of memory by using large packets
 accidentally.
 
 You can also get strange problems with large packets if you are using
 large `BLOB' values but have not given `mysqld' access to enough memory
 to handle the query.  If you suspect this is the case, try adding
 `ulimit -d 256000' to the beginning of the `mysqld_safe' script and
 restarting `mysqld'.
 

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