WL#903: Improved online variable setting
There are two issues with handling variables today which makes users a bit frustrated. 1) missleading error message: mysql> set global innodb_buffer_pool_size=1; ERROR 1193: Unknown system variable 'innodb_buffer_pool_size' this is variable but it is just not live settable, which is what error message shall say [ Noted added 2010-06-15 ] The message now is: ERROR 1238 (HY000): Variable 'innodb_buffer_pool_size' is a read only variable 2) No good way to quess which variables can be set and which can't. The good way might be to add "SHOW EXTENDED VARIABLES" which would show - variable name - variable type (GLOBAL/SESSION) - if it can be set online - if it is readonly (can't be set directly but rather some explicit way), such as have_innodb - variable physical type (string/number etc) - minumum and maximum values allowed - short description (it would be good to make one match help one)
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