TokuDB Hot Column Expansion

I need to expand a varchar field length from 255 to 4000. I am using tokudb_version: tokudb-7.5.8 running on Linux 3.16.0-60-generic #80~14.04.1-Ubuntu SMP Wed Jan 20 13:37:48 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux I know TokuDB supports Hot Column operations but this is not working for me ( number of rows ~ 210 million) Show variables file: https://drive.google.com/file/d/0B5noFLrbjDjzSW9wdnVjb095Q0U/view?usp=sharing Alter command alter table test_table modify test_column varchar(4000); Show processlist: mysql> show processlist; +----+------+-----------+---------------+---------+------+---------------------------------------------------------+------------------------------------------------------------+-----------+---------------+ | Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined | +----+------+-----------+---------------+---------+------+---------------------------------------------------------+------------------------------------------------------------+-----------+---------------+ | 6 | root | localhost | NULL | Query | 0 | init | show processlist | 0 | 0 | | 7 | root | localhost | test | Query | 461 | Queried about 2445001 rows, Inserted about 2445000 rows | alter table test_table modify test_column varchar(4000) | 0 | 0 | +----+------+-----------+---------------+---------+------+---------------------------------------------------------+------------------------------------------------------------+-----------+---------------+ 2 rows in set (0.00 sec) Any idea which options I might need to set because it's currently processing at ~ 6k per second(which might take me ~10 hours)