问MySQL 8.0.23 tmp表不断填充

EN

create table medicare_fee_history (
        year int unsigned,
        mac int unsigned,
        locality int unsigned,
        hcpcs varchar(10),
        modifier varchar(10),
        index (mac, locality, hcpcs, modifier),
        non_facility decimal(17, 4),
        facility decimal(17, 4)
) engine = myisam;

load data local infile 'PFALL.csv'
into table medicare_fee_history
fields terminated by ',' enclosed by '"'
(year, mac, locality, hcpcs, modifier, non_facility, facility);

create table medicare_fee_first (
        year int unsigned,
        hcpcs varchar(10),
        modifier varchar(10),
        index (hcpcs, modifier),
        facility decimal(17, 4),
        non_facility decimal(17, 4)
) engine = myisam;

insert into medicare_fee_first (year, hcpcs, modifier, facility, non_facility)
(
        select min(year), hcpcs, modifier, avg(facility), avg(non_facility)
        from medicare_fee_history group by hcpcs, modifier
);

mysql> show variables like '%tmp%';
+---------------------------------+----------------------+
| Variable_name                   | Value                |
+---------------------------------+----------------------+
| default_tmp_storage_engine      | InnoDB               |
| innodb_tmpdir                   |                      |
| internal_tmp_mem_storage_engine | TempTable            |
| slave_load_tmpdir               | /tmp                 |
| tmp_table_size                  | 18446744073709551615 |
| tmpdir                          | /tmp                 |
+---------------------------------+----------------------+
6 rows in set (0.00 sec)

mysql> show variables like '%temp%';
+-----------------------------+-----------------------+
| Variable_name               | Value                 |
+-----------------------------+-----------------------+
| avoid_temporal_upgrade      | OFF                   |
| innodb_temp_data_file_path  | ibtmp1:12M:autoextend |
| innodb_temp_tablespaces_dir | ./#innodb_temp/       |
| show_old_temporals          | OFF                   |
| temptable_max_mmap          | 1073741824            |
| temptable_max_ram           | 1073741824            |
| temptable_use_mmap          | ON                    |
+-----------------------------+-----------------------+
7 rows in set (0.00 sec)