[burgreblast]

Actually, it's 1000-9000 messages per server per day. Or about 1 message every 10-100 seconds.

Of course, that's just the new messages inbound. They may need to distribute that single message to 100M people (who likely won't even see it, but still.)

Problems that are trivally solvable with one database don't simply scale by adding more DBs or machines. Scaling isn't easy or they would have done it. I'm in no way disparaging their team, because I don't know what kind of constraints they had getting to this point.

Still, I'd bet it could be optimized by 2+ of orders of magnitude if people sat down and re-evaluated the whole structure again at this point in time.

Regardless, is that really a priority?

They may have bigger issues on their plate now (growing revenue, growing users, making users happy). Assuming their business can generate the cash flow to overcome the inefficiencies, they may be better served to focus on growth.