SELECT @@session.character_set_connection;
@@session.character_set_connection
latin1
SET @@session.session_track_system_variables='character_set_connection';
# tracking info on
SET NAMES 'utf8';
-- Tracker : SESSION_TRACK_SYSTEM_VARIABLES
-- character_set_connection
-- utf8

SET NAMES 'big5';
-- Tracker : SESSION_TRACK_SYSTEM_VARIABLES
-- character_set_connection
-- big5

# tracking info on once
SET NAMES 'utf8';
-- Tracker : SESSION_TRACK_SYSTEM_VARIABLES
-- character_set_connection
-- utf8

SET NAMES 'big5';
# tracking info on
SET NAMES 'utf8';
-- Tracker : SESSION_TRACK_SYSTEM_VARIABLES
-- character_set_connection
-- utf8

# tracking info off once
SET NAMES 'big5';
SET @@session.session_track_system_variables= default;
#
# MDEV-16470 - Session user variables tracker
#
SET @@session.session_track_user_variables=1;
SET @a=1;
SET @b=NULL;
SELECT @c:=10;
@c:=10
10
SET @@session.session_track_user_variables=0;