I was staring at my Convex dashboard, confused. Convex is the reactive backend I use for a chat app: it stores the data and, the part that matters here, it keeps your queries live , so the UI updates the instant the data changes. The dashboard has a meter called "Database Bandwidth," and for two users, me on a dev account and me on a prod account, poking the app for maybe half an hour, it was reading tens of megabytes a day. That made no sense to me. It's a chat app. The actual messages we...