In node A, go to Administration > Look and Feel> Content Layouts and change the Page Layout, then view any page in that node and you'll see the change.
But, if you go to node B, and view any page, you won't see the change

If yo go to Node B, Administration -> Look and Feel -> Content Layouts and edit the Page Layout, you'll see the change, but until you save change, it will become active.

The issue is not the database propagation but the awareness of the change (event?)