SET GLOBAL mroonga_n_workers = 0;
SHOW GLOBAL VARIABLES LIKE 'mroonga_n_workers';
Variable_name	Value
mroonga_n_workers	0
SELECT
JSON_EXTRACT(mroonga_command('status'), '$.default_n_workers') AS default_n_workers,
JSON_EXTRACT(mroonga_command('status'), '$.n_workers') AS n_workers;
default_n_workers	n_workers
0	0
