• Beginning with MySQL 5.6.6, several MySQL Server parameters have defaults that differ from
previous releases. The motivation for these changes is to provide better out-of-box performance and
to reduce the need for the database administrator to change settings manually. These changes are
subject to possible revision in future releases as we gain feedback.
In some cases, a parameter has a different static default value. In other cases, the server
autosizes a parameter at startup using a formula based on other related parameters or server
host configuration, rather than using a static value. For example, the setting for back_log 
now is its previous default of 50, adjusted up by an amount proportional to the value of
max_connections . The idea behind autosizing is that when the server has information
available to make a decision about a parameter setting likely to be better than a fixed default, it will.
The following table summarizes changes to defaults. Any of these can be overridden by specifying
an explicit value at server startup.
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