In MySQL 5.6, several MySQL Server parameter defaults differ from the defaults in previous releases. The motivation for these changes is to provide better out-of-box performance and to reduce the need for database administrators to change settings manually.
In some cases, a parameter has a different fixed 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 fixed value. For example, the
back_log is its
previous default of 50, adjusted up by an amount proportional to
the value of
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. The Version column indicates when each default changed. For variables that are autosized, the main variable description provides additional detail about the sizing algorithm. See Section 5.1.7, “Server System Variables”, and Section 14.14, “InnoDB Startup Options and System Variables”. Any of these default settings can be overridden by specifying an explicit value at server startup.
Table 5.1 Changes to Server Defaults in MySQL 5.6
In MySQL 5.6.6, the default for
CRC32. For compatibility reasons, the default
was returned in 5.6.7 to