SET @global_start_value = @@global.ndb_optimized_node_selection;
SELECT @global_start_value;
@global_start_value
3
set session ndb_optimized_node_selection=3;
show variables like 'ndb_optimized_node_selection';
Variable_name	Value
ndb_optimized_node_selection	3
set session ndb_optimized_node_selection=0;
show variables like 'ndb_optimized_node_selection';
Variable_name	Value
ndb_optimized_node_selection	0
set session ndb_optimized_node_selection=4;
Warnings:
Warning	1292	Truncated incorrect ndb_optimized_node_selection value: '4'
show variables like 'ndb_optimized_node_selection';
Variable_name	Value
ndb_optimized_node_selection	3
set global ndb_optimized_node_selection=1;
show variables like 'ndb_optimized_node_selection';
Variable_name	Value
ndb_optimized_node_selection	3
show variables like 'ndb_optimized_node_selection';
Variable_name	Value
ndb_optimized_node_selection	1
set global ndb_optimized_node_selection=3;
SELECT @@global.ndb_optimized_node_selection;
@@global.ndb_optimized_node_selection
3