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 16select * from information_schema.session_variables where variable_name='extra_max_connections'; 17VARIABLE_NAME VARIABLE_VALUE 18EXTRA_MAX_CONNECTIONS 1 19set global extra_max_connections=1; 20select @@global.extra_max_connections; 21@@global.extra_max_connections 221 23set session extra_max_connections=1; 24ERROR HY000: Variable 'extra_max_connections' is a GLOBAL variable and should be set with SET GLOBAL 25set global extra_max_connections=1.1; 26ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 27set global extra_max_connections=1e1; 28ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 29set global extra_max_connections="foo"; 30ERROR 42000: Incorrect argument type to variable 'extra_max_connections' 31set global extra_max_connections=0; 32Warnings: 33Warning 1292 Truncated incorrect extra_max_connections value: '0' 34select @@global.extra_max_connections; 35@@global.extra_max_connections 361 37set global extra_max_connections=cast(-1 as unsigned int); 38Warnings: 39Note 1105 Cast to unsigned converted negative integer to it's positive complement 40Warning 1292 Truncated incorrect extra_max_connections value: '18446744073709551615' 41select @@global.extra_max_connections; 42@@global.extra_max_connections 43100000 44SET @@global.extra_max_connections = @start_global_value; 45