The DBAs have expressed concerns about the ever-growing size of the watchlist table. In Community-Tech's research for Expiring-Watchlist-Items, we discovered the accounts with the most watched items are almost always bots, and appear to be only because the "add pages and files I create to my watchlist" preference is on by default. It's not surprising that bots create so many pages, since naturally they operate at a higher rate than humans.
Ignore auto-watch preferences when an account is added to a user group with the bot permission. This seems rather uncontroversial, as bots conceivably have little use for the watchlist. If they do need it for whatever reason, the need to hear the use-case. We should solicit input from the community before making any decisions.
Some quick data
- commonswiki: 14% (~22 million rows) of the watchlist table are owed to bots, which appear to be bots that upload files and simply have the default preference set to watch them
- wikidatawiki: 1.1% (~91 million rows) -- probably bots that automatically create items after articles on Wikipedia are created
- enwiki: 4.7% (~10.3 million rows) -- e.g. counter-vandalism bots that create User talk pages when issuing warnings
- mgwiktionary: 99.8% (~13.2 million rows) -- a single bot mass-created nearly every entry on the wiki