When importing data to an external table through copy into, the data is overwritten in CnosDB

Question

I created an external table using a certain path A, and at that time, there were 8192 rows of data in the table.

CREATE EXTERNAL TABLE local_to_table_json STORED AS JSON LOCATION 'file:///tmp/data/json_out/';

Then, I imported a JSON file B from another path into this external table,

copy into local_to_table_json from 'query_server/test/resource/json/part-0.json' FILE_FORMAT = (TYPE = 'JSON', DELIMITER = ',');

but after the import, I found that the table only contained the data from file B.

I believe that after creating an external table using a certain path, when copying data files into this external table multiple times, all the data should be saved instead of replacing the previously copied data files.