1SET @start_global_value = @@global.extra_max_connections; 2select @@global.extra_max_connections; 3@@global.extra_max_connections 41 5select @@session.extra_max_connections; 6ERROR HY000: Variable 'extra_max_connections' is a GLOBAL variable 7show global variables like 'extra_max_connections'; 8Variable_name Value 9extra_max_connections 1 10show session variables like 'extra_max_connections'; 11Variable_name Value 12extra_max_connections 1 13select * from information_schema.global_variables where variable_name='extra_max_connections'; 14VARIABLE_NAME VARIABLE_VALUE 15EXTRA_MAX_CONNECTIONS 1 16Warnings: 17Warning 1287 'INFORMATION_SCHEMA.GLOBAL_VARIABLES' is deprecated and will be removed in a future release. Please use performance_schema.global_variables instead 18select * from information_schema.session_variables where variable_name='extra_max_connections'; 19VARIABLE_NAME VARIABLE_VALUE 20EXTRA_MAX_CONNECTIONS 1 21Warnings: 22Warning 1287 'INFORMATION_SCHEMA.SESSION_VARIABLES' is deprecated and will be removed in a future release. Please use performance_schema.session_variables instead 23set global extra_max_connections=1; 24select @@global.extra_max_connections; 25@@global.extra_max_connections 261 27set session extra_max_connections=1; 28ERROR HY000: Variable 'extra_max_connections' is a GLOBAL variable and should be set with SET GLOBAL 29set global extra_max_connections=1.1; 30ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 31set global extra_max_connections=1e1; 32ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 33set global extra_max_connections="foo"; 34ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 35set global extra_max_connections=0; 36Warnings: 37Warning 1292 Truncated incorrect extra_max_connections value: '0' 38select @@global.extra_max_connections; 39@@global.extra_max_connections 401 41set global extra_max_connections=cast(-1 as unsigned int); 42Warnings: 43Warning 1292 Truncated incorrect extra_max_connections value: '18446744073709551615' 44select @@global.extra_max_connections; 45@@global.extra_max_connections 46100000 47SET @@global.extra_max_connections = @start_global_value; 48