“The Roon software absolutely knows which files are slated for deletion, otherwise it wouldn’t know which entries needed to be deleted from the database.”… I never said otherwise. Roon, as it clearly indicates under Library Cleanup, indexes every single entry you make in Roon. In all likelihood, it’s via something like a hexadecimal number, as in hex, you can index over one million entries with just five hexadecimal digits. Neither you, nor I designed the Roon software, so neither of us knows for sure what happens…it’s pure conjecture. But the logic of efficiency leads me to suspect that when you add something to Roon, say “Money” by Pink Floyd, it adds both the file information “Pink Floyd” + “Dark Side of the Moon” + “Money” plus “index number” (Let’s say 1a2b3) to create an entry. Now, when you delete it, for efficiency’s sake, it makes sense that when “Money” is deleted that everything except the index number 1a2b3, and possible amending that number with a 1,2 or 3 (the cleanup group). Does Roon do it that way?? Who knows, but from an efficiency standpoint, it makes 100% sense. You can track that entry from it’s inception to it’s ultimate demise with just with a short index number.
another reason why a system like mine makes sense, take this example… I delete all 44.1/16 entries as I have decided to go all hi-res. Let’s say that’s 2500 entries. Once deleted, I do a backup. I know from experience, that the database does not have the file information, as I have had to restore from that backup (I auto backup every midnight, and 2-3 times have had to do a restore early in the morning), and it did not put the songs back into my library. But, the first group of Library Cleanup items shows 2500. The only logical way that I can think of for that to happen is via something similar to what I suggest, i.e., only the index number survives deletion. Once I delete those 2500 through Library Cleanup, then the 2500 indices are lost. I wish a Roon software designer would explain the mechanics of this for everyone, but I bet my way doesn’t vary too far from theirs.