explain output difference in filtered column

 explain extended select * from t1_bin where a between 'a-3a' and 'zzzzzzzzz';

 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

-1	SIMPLE	t1_bin	ALL	NULL	NULL	NULL	NULL	10	58.82	Using where

+1	SIMPLE	t1_bin	ALL	NULL	NULL	NULL	NULL	10	10.00	Using where

set optimizer_record_context=ON;

create table ten(a int primary key);

insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

set histogram_size=100;

set histogram_type='double_prec_hb';

create table t1_bin (a varchar(255));

insert into t1_bin select concat('a-', a) from ten;

analyze table t1_bin persistent for all;

select hex(histogram) from mysql.column_stats where table_name='t1_bin';

explain extended select * from t1_bin where a between 'a-3a' and 'zzzzzzzzz';

SELECT context INTO DUMPFILE 'context1.txt' FROM INFORMATION_SCHEMA.OPTIMIZER_CONTEXT;

source /home/ppandith/test2/bld/data2/m8/context1.txt