MINI MINI MANI MO

SET @start_global_value = @@global.gtid_executed_compression_period;
SELECT @start_global_value;
@start_global_value
1000
#
# It exists as a global variable
#
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
1000
SHOW GLOBAL VARIABLES LIKE 'gtid_executed_compression_period';
Variable_name	Value
gtid_executed_compression_period	1000
SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE
VARIABLE_NAME = 'gtid_executed_compression_period';
VARIABLE_NAME	VARIABLE_VALUE
GTID_EXECUTED_COMPRESSION_PERIOD	1000
#
# It is not a session variable
#
SELECT @@SESSION.gtid_executed_compression_period;
ERROR HY000: Variable 'gtid_executed_compression_period' is a GLOBAL variable
SET SESSION gtid_executed_compression_period= 2;
ERROR HY000: Variable 'gtid_executed_compression_period' is a GLOBAL variable and should be set with SET GLOBAL
SHOW SESSION VARIABLES LIKE 'gtid_executed_compression_period';
Variable_name	Value
gtid_executed_compression_period	1000
SHOW SESSION VARIABLES LIKE 'gtid_executed_compression_period';
Variable_name	Value
gtid_executed_compression_period	1000
SELECT * FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE
VARIABLE_NAME ='gtid_executed_compression_period';
VARIABLE_NAME	VARIABLE_VALUE
GTID_EXECUTED_COMPRESSION_PERIOD	1000
#
# Verify that it's writable
#
SET GLOBAL gtid_executed_compression_period= 0;
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
0
SET GLOBAL gtid_executed_compression_period= 5000;
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
5000
SET GLOBAL gtid_executed_compression_period= 4294967295;
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
4294967295
#
# Verify that it could not bet set with invalid values
#
SET GLOBAL gtid_executed_compression_period= -1;
Warnings:
Warning	1292	Truncated incorrect gtid_executed_compression_period value: '-1'
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
0
SET GLOBAL gtid_executed_compression_period= 4294967296;
Warnings:
Warning	1292	Truncated incorrect gtid_executed_compression_period value: '4294967296'
SELECT @@GLOBAL.gtid_executed_compression_period;
@@GLOBAL.gtid_executed_compression_period
4294967295
set global gtid_executed_compression_period= 1.1;
ERROR 42000: Incorrect argument type to variable 'gtid_executed_compression_period'
set global gtid_executed_compression_period= 1e1;
ERROR 42000: Incorrect argument type to variable 'gtid_executed_compression_period'
set global gtid_executed_compression_period= "foobar";
ERROR 42000: Incorrect argument type to variable 'gtid_executed_compression_period'
SET @@global.gtid_executed_compression_period= @start_global_value;
SELECT @@global.gtid_executed_compression_period;
@@global.gtid_executed_compression_period
1000