alt Hacker NewsEmphasis mine:
> Each invocation runs in a lightweight V8 isolate, close to Telegram's own systems, so calls to the Bot API and your database are quick and reliable.
Telegram’s servers are distributed worldwide. I understand that the calls to the Bot API may be quick because the serverless code would be propagated to the edge, but how does it handle an SQLite DB? Is that also replicated to guarantee quick access from anywhere?
Replies
My first guess would be replicaton isn't that critical, because a user would mostly interact with an instance that's nearby, and this instance has their data. But the page mentions:
> Games and Tools — including leaderboards, quizzes and more.
A leaderboard that's globally consistent, huh, that's not trivial.
Maybe they just propagate the SQL commands to all their servers...
I guess the v8 isolate is heavily restricted and sandboxed and can't be used to access the local filesystem
Telegram's servers are far from "distributed worldwide": In fact, it currently has only 5 logical "data center"s, and while DC3 is still on, clues [0] seem to suggest DC3 doesn't actually carry user data at all now, and both DC2 and 4 are in Amsterdam, so essentially they just need to serve 3 locations.
Also, Telegram's protocol design only allows for connecting to user's home DC for any write interactions (except media, which in most cases still is home DC, or a "media DC" alongside the home DC). Bots are based on the same DC of the user, so almost all meaningful interactions will happen only on one DC for any specific bot.
[0]: https://dev.moe/en/3025