SET @start_global_value = @@global.innodb_compression_level;
SELECT @start_global_value;
@start_global_value
6
Valid value 0-9
select @@global.innodb_compression_level <= 9;
@@global.innodb_compression_level <= 9
1
select @@global.innodb_compression_level;
@@global.innodb_compression_level
6
select @@session.innodb_compression_level;
ERROR HY000: Variable 'innodb_compression_level' is a GLOBAL variable
show global variables like 'innodb_compression_level';
Variable_name	Value
innodb_compression_level	6
show session variables like 'innodb_compression_level';
Variable_name	Value
innodb_compression_level	6
select * from information_schema.global_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	6
select * from information_schema.session_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	6
set global innodb_compression_level=2;
select @@global.innodb_compression_level;
@@global.innodb_compression_level
2
select * from information_schema.global_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	2
select * from information_schema.session_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	2
set session innodb_compression_level=4;
ERROR HY000: Variable 'innodb_compression_level' is a GLOBAL variable and should be set with SET GLOBAL
set global innodb_compression_level=1.1;
ERROR 42000: Incorrect argument type to variable 'innodb_compression_level'
set global innodb_compression_level=1e1;
ERROR 42000: Incorrect argument type to variable 'innodb_compression_level'
set global innodb_compression_level="foo";
ERROR 42000: Incorrect argument type to variable 'innodb_compression_level'
set global innodb_compression_level=10;
Warnings:
Warning	1292	Truncated incorrect innodb_compression_level value: '10'
select @@global.innodb_compression_level;
@@global.innodb_compression_level
9
select * from information_schema.global_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	9
set global innodb_compression_level=-7;
Warnings:
Warning	1292	Truncated incorrect innodb_compression_level value: '-7'
select @@global.innodb_compression_level;
@@global.innodb_compression_level
0
select * from information_schema.global_variables where variable_name='innodb_compression_level';
VARIABLE_NAME	VARIABLE_VALUE
INNODB_COMPRESSION_LEVEL	0
set global innodb_compression_level=0;
select @@global.innodb_compression_level;
@@global.innodb_compression_level
0
set global innodb_compression_level=9;
select @@global.innodb_compression_level;
@@global.innodb_compression_level
9
SET @@global.innodb_compression_level = @start_global_value;
SELECT @@global.innodb_compression_level;
@@global.innodb_compression_level
6
