My home network consists of a server holding all my media files, a mysql database on the server to hold kodi info, and kodi clients (windows, raspberry pi) that play the actual media. everything has worked nicely so far

 

Can anyone explain what a headless kodi server is, and how it might improve my current network setup?

 

From what I understand it does library updates in the background so my clients dont need to be online, which I'm assuming will update my mysql database in the process. But once clients boot up, don't they still need to poll the database and refresh their own library?

You have the right idea, however the time of the update for the client to see the newly scanned media is basically instant (the thumbnail can take a moment to load).

Instead of having your client set to update the library on startup, or complete a manual scan, this is all done for you.

 

In my use case I use a Windows VM with Utrorrent to do my downloading, and a file sync manager to move over the files to the correct shares when completed.

At the end of the transfer it runs a batch script that tell the headless kodi to do a library update, which updates the MYSQL server.

Of course there are many ways to complete this same process, however I am happy with the way things are setup/running for me so far.