drop table if exists t1;show variables like "ft\_%";Variable_name Valueft_boolean_syntax + -><()~*:""&|ft_max_word_len 84ft_min_word_len 4ft_query_expansion_limit 20ft_stopword_file (built-in)create table t1 (b text not null);insert t1 values ('aaaaaa bbbbbb cccccc');insert t1 values ('bbbbbb cccccc');insert t1 values ('aaaaaa cccccc');select * from t1 where match b against ('+aaaaaa bbbbbb' in boolean mode);baaaaaa bbbbbb ccccccaaaaaa ccccccset ft_boolean_syntax=' +-><()~*:""&|';ERROR HY000: Variable 'ft_boolean_syntax' is a GLOBAL variable and should be set with SET GLOBALset global ft_boolean_syntax=' +-><()~*:""&|';select * from t1 where match b against ('+aaaaaa bbbbbb' in boolean mode);baaaaaa bbbbbb ccccccbbbbbb ccccccset global ft_boolean_syntax='@ -><()~*:""&|';select * from t1 where match b against ('+aaaaaa bbbbbb' in boolean mode);baaaaaa bbbbbb ccccccbbbbbb ccccccaaaaaa ccccccselect * from t1 where match b against ('+aaaaaa @bbbbbb' in boolean mode);baaaaaa bbbbbb ccccccbbbbbb ccccccset global ft_boolean_syntax='@ -><()~*:""@|';ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of '@ -><()~*:""@|'set global ft_boolean_syntax='+ -><()~*:""@!|';ERROR 42000: Variable 'ft_boolean_syntax' can't be set to the value of '+ -><()~*:""@!|'drop table t1;