Acl table problem

**mqtt_acl table**
allow: 1, ipaddr: null, username: master, clientid: null, access: 1, topic: test
allow: 0, ipaddr: null, username: $all, clientid: null, access: 2, topic: test

**auth.pgsql.acl_query**
select allow, ipaddr, username, clientid, access, topic from mqtt_acl where ipaddr = '%a' or username = '%u' or username = '$all' or clientid = '%c'

I created the table and the query as above. But I want user 'master' to be able to read the test topic but not write it. I looked at the documents on the internet but could not find any solution.
Where am I making a mistake?