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blunders
Asked: 2011-03-09 10:15:21 +0800 CST

Setting "max_allowed_packet" -- commandline vs config?

  • 772

What is the difference between setting the max_allowed_packet via the MySQL commandline using:

set global max_allowed_packet=100000000;

And setting it by editing the MySQL my.ini (Win) or my.cnf (Linux) config and putting the following code under [mysqld]:

max_allowed_packet=100M
mysql configuration

2 Answers

  1. Best Answer
    set global max_allowed_packet = 1000000000

    This sets max_allowed_packet it to 1 billion bytes or 1 GB.

    max_allowed_packet=100M

    This sets it to 104857600 bytes or 100 MiB.

    Assuming your extra zero is unintended, the only difference between setting via command line and config is that the config file supports shorthand using JEDEC binary prefixes. Plus, the set global will be lost on server restart.

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  2. Another major difference is the fact that thesetting of max_allowed_packet will survive a mysql restart if you set the variable in my.cnf (or my.ini)

    Additionally, if you set that variable globally, it would make sense to set the session variables as well, especially if the session needs it.

    Ugh, I just read hobodave's answer. Clearer answer. I give him a +1

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