permission_id int(11) not_null auto_increment
agent_id varchar(100) not_null
domain varchar(100) not_null
permission_level enum('read','write','full') not_null
created_at timestamp NULL default(current_timestamp)
updated_at timestamp NULL default(current_timestamp) ON UPDATE current_timestamp()

--
primary permission_id
unique unique_agent_domain agent_id domain
idx_agent_id agent_id 
idx_domain domain 
idx_permission_level permission_level

##
engine innodb
character_set utf8mb4
collate utf8mb4_unicode_ci