兼容海康不规范的xml，大幅度提高通道分页查询速度，优化节点的保活。

sql/update.sql

@@ -1 +1,7 @@
-ALTER TABLE stream_proxy ADD status bit(1) not null;
+ALTER TABLE stream_proxy ADD status bit(1) not null;
+
+# 去除子查询优化查询速度
+alter table device_channel
+    add subCount int default 0 null;
+
+update device_channel dc set dc.subCount = (select  te.count from (SELECT count(0) as count FROM device_channel WHERE parentId = dc.channelId) te)