In the current implementation, Tajo removes a data directory when a user issues 'drop table' command. But, it is very dangerous in many cases. For example, some users may lost large data sets.
In default, 'DROP TABLE' should not remove a data directory.
, and we need to add a config property 'tajo.command.drop_table.data_removal' for those who want to change the behavior of 'drop table'. In addition, Tajo should provide 'DROP TABLE table_name PURGE' for removing all data.