Hashtag federation

Has anyone considered federating hashtag searches? I know a previous post talked about relays for public posts but I haven’t found a discussion regarding tag federation yet. This seems a bit easier to do then public post federation because it can be limited in scope and handled in an on-the-fly manner.

The way I see it, the pod can have configuration settings that the podmin can set that would “subscribe” to other servers within the network. When a user searches for a tag within his registered pod, the pod can also search for that tag on other servers that are subscribed to. No need to proactively run relays. Just server-to-server exchange at the time of the users search request. I would think resource-wise this would be less then a user going to every other pod to search for those tags using the url parameters (which also requires the server to spend time sending images and render instructions to the browser.) The other end (the pod that has been subscribed to) can easily block unwanted subscribers within the config files if they chose to. You can also slow and limit how much data is exchanged to reduce unintended DOS to a pod.

Just something to consider.