Advantages and disadvantages of various database connection modes in C/S Mode

I. Headquarters database (master )-
1. Store database (slave1)
2. Store database (slave2)
...
Data of each store is synchronized with the master through the publishing and subscription mechanisms. Data of each store can be obtained from other stores by querying data from the master. VPN security points are used for network connection.
The master node is connected to dozens of stores nationwide.

II. The ADO store is connected to the database area of the Headquarters. Generally, it is in the same province.

ADO connection is more convenient, as long as you can directly connect to it, it is easy to do, it is really not good to use VPN, but a high-end, you can also test the use of peanut, login terminal Login

You can also upload and download data between the Headquarters and the data

3. Each sub-Organization automatically uploads data to the Headquarters database throughMulti-layer mechanism?

To change the architecture, data must be synchronized between database servers?

Using a three-tier architecture, all store data is uploaded to the server?