Wow. Why don't they use in-house Google databases, which are supposedly vastly more scalable than MySQL?
The Spanner team noticeably put out https://cloud.google.com/blog/products/databases/inside-clou... a few years back, which tl;drs that they managed to get a reliable enough network that partitions don't really happen anymore and so you can get both C _and_ A from the CAP theorem. I don't think that Vitess is quite at that level, especially since you can self-host it and thus the devs don't have such network-level uptime guarantees.
I am just speculating here but I doubt that YouTube migrated to Spanner so that they could do cross-server transactions. I would think consolidating the Ops burden into the GCP org and also serving as a trophy "customer" were higher on the list of reasons. But again, just speculating...
> Are cross-server transactions scalable? Would anyone architect a system that did them en masse unless they absolutely 100% had to?
As a long time Vitess user and contributor/maintainer, this perfectly describes the issue. Minimal effort has been put into solving cross shard / 2PC transactions because a well designed system rarely needs it.
https://static.googleusercontent.com/media/research.google.c...
It is designed from the ground-up to be globally distributed. Some other databases like FoundationDB (now owned and killed? by Apple) and CockroachDB were designed to scale across multiple datacenters.
Correction: FoundationDB is alive as open-source again, yay!
- https://news.ycombinator.com/item?id=9259986 - Apple Acquires FoundationDB - March 24, 2015
- Comparison between March 25 and March 14, 2015 - https://web.archive.org/web/20150314231702/https://foundatio... (14th March) > https://web.archive.org/web/20150325003252/https://foundatio... (25th March)