MySQL :: MySQL 5.7 Reference Manual :: 8.9.2 Switchable Optimizations
8.9.2 Switchable Optimizations
The optimizer_switch system variable enables control over optimizer behavior. Its value is a set of flags, each of which has a value of on
or off
to indicate whether the corresponding optimizer behavior is enabled or disabled. This variable has global and session values and can be changed at runtime. The global default can be set at server startup.文章来源:https://uudwc.com/A/0npvZ
To see the current set of optimizer flags, select the variable value:文章来源地址https://uudwc.com/A/0npvZ
mysql> SELECT @