SET @start_global_value = @@global.encrypt_tmp_disk_tables;
select @@global.encrypt_tmp_disk_tables;
@@global.encrypt_tmp_disk_tables
0
select @@session.encrypt_tmp_disk_tables;
ERROR HY000: Variable 'encrypt_tmp_disk_tables' is a GLOBAL variable
show global variables like 'encrypt_tmp_disk_tables';
Variable_name	Value
encrypt_tmp_disk_tables	OFF
show session variables like 'encrypt_tmp_disk_tables';
Variable_name	Value
encrypt_tmp_disk_tables	OFF
select * from information_schema.global_variables
where variable_name='encrypt_tmp_disk_tables';
VARIABLE_NAME	VARIABLE_VALUE
ENCRYPT_TMP_DISK_TABLES	OFF
select * from information_schema.session_variables
where variable_name='encrypt_tmp_disk_tables';
VARIABLE_NAME	VARIABLE_VALUE
ENCRYPT_TMP_DISK_TABLES	OFF
set global encrypt_tmp_disk_tables=ON;
select @@global.encrypt_tmp_disk_tables;
@@global.encrypt_tmp_disk_tables
1
set global encrypt_tmp_disk_tables=OFF;
select @@global.encrypt_tmp_disk_tables;
@@global.encrypt_tmp_disk_tables
0
set global encrypt_tmp_disk_tables=1;
select @@global.encrypt_tmp_disk_tables;
@@global.encrypt_tmp_disk_tables
1
set session encrypt_tmp_disk_tables=1;
ERROR HY000: Variable 'encrypt_tmp_disk_tables' is a GLOBAL variable and should be set with SET GLOBAL
set global encrypt_tmp_disk_tables=1.1;
ERROR 42000: Incorrect argument type to variable 'encrypt_tmp_disk_tables'
set global encrypt_tmp_disk_tables=1e1;
ERROR 42000: Incorrect argument type to variable 'encrypt_tmp_disk_tables'
set global encrypt_tmp_disk_tables="foo";
ERROR 42000: Variable 'encrypt_tmp_disk_tables' can't be set to the value of 'foo'
SET @@global.encrypt_tmp_disk_tables = @start_global_value;