Real Time Monitoring Architecture for distributed Database

I am building a real time monitoring tool.

Here is the Scenario:

I have multiple nodes(Servers) running there own database (SQL) instance. I want to see the information from those databases on one system. So as far as I know there could be two possible solutions: 1. Query each and every Node to get updates form there database 2. Get the data (database) from every node and put it on one system to query just one database.

I would really appreciate if somebody can help me with the pros and cons of both the solution or any other approach ?