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MySql max_allowed_packet

Posted on 2011-09-20
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Last Modified: 2012-06-12
I setup new LAMP VM (has 4Gb ram) and need to restore 9Gb sql file to a database in MySQL.
I configured my.cnf file with
[mysql]
max_allowed_packet=2G


I try to import sql file with 'mysql' command with '--max_allowed_packet' option but failed with below message.

Get a packet bigger than 'max_allowed_packet' bytes.

I figured out the packet size in phpmyadmin but ...
@@max_allowed_packet
1048576

Any suggestion?
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Question by:Ken_Kim
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nbhu earned 500 total points
ID: 36566775
Hi,
The default is 1MB,2G is more than the upper limit, max is 1G.
From Mysql documentation:
max_allowed_packet
Command-Line Format       --max_allowed_packet=#
Option-File Format       max_allowed_packet
Option Sets Variable       Yes, max_allowed_packet
Variable Name       max_allowed_packet
Variable Scope       Global
Dynamic Variable       Yes
        Permitted Values
Type       numeric
Default       1048576
Range       1024 .. 1073741824

The maximum size of one packet or any generated/intermediate string.

The packet message buffer is initialized to net_buffer_length bytes, but can grow up to max_allowed_packet bytes when needed. This value by default is small, to catch large (possibly incorrect) packets.

You must increase this value if you are using large BLOB columns or long strings. It should be as big as the largest BLOB you want to use. The protocol limit for max_allowed_packet is 1GB. The value should be a multiple of 1024; nonmultiples are rounded down to the nearest multiple.

When you change the message buffer size by changing the value of the max_allowed_packet variable, you should also change the buffer size on the client side if your client program permits it. On the client side, max_allowed_packet has a default of 1GB. Some programs such as mysql and mysqldump enable you to change the client-side value by setting max_allowed_packet on the command line or in an option file.

The session value of this variable is read only.

Regards, nbhu
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Expert Comment

by:nbhu
ID: 36566794
P.S.
I think your setting is too big, so it is invalid and ignored.
@@max_allowed_packet
1048576
This is the dafault setting.
Regards, nbhu
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Author Comment

by:Ken_Kim
ID: 36566822
It's only working in session like putty.
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Expert Comment

by:nbhu
ID: 36567233
Hi,
You can put it in my.ini or my.cnf, so it remains always valid.
We do this on windows, and it is working.
Regards, nbhu
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Expert Comment

by:nbhu
ID: 36567243
You have to put it in the following section:
[mysqld]

# The TCP/IP Port the MySQL Server will listen on
port=3306
max_allowed_packet=4M


Regards, nbhu
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Expert Comment

by:pete-mcpetey
ID: 37819386
If it's working in a PuTTY SSH session, you're good. There is no way you are going to get a 9GB file through a client like phpMyAdmin.
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