sentry/config/clickhouse/users.xml

<clickhouse>
    <profiles>
      <default>
	<!-- artificially low value to induce query failures -->
        <!-- <max_memory_usage>1048576</max_memory_usage> -->
      </default>
    </profiles>
    <users>
        <default>
            <!-- let the default user do everything -->
            <access_management>1</access_management>
        </default>
    </users>
</clickhouse>