4 ms·
Interested in a concrete example of where you see a migration being impossible without downtime; I'm not aware of Amazon or Google taking their APIs down for ma
by theptip 9y ago
Interested in a concrete example of where you see a migration being impossible without downtime; I'm not aware of Amazon or Google taking their APIs down for maintenance, which suggests that you can solve these problems with enough engineering spend.
> depending on... how coupled everything is
If you're just saying here that some systems aren't currently able to migrate in a hitless way, rather than claiming that it would never be possible for some systems, then I fully agree. Hitless migrations require a lot of work, and probably aren't worth the cost for many applications/systems.
- stickfigure 9y agoNeither Amazon nor Google run off of an RDBMS. Relational databases are awesome, but it's much harder to achieve 100% uptime compared to schemaless, distributed, replicated data stores. You easily can take down your system with one innocuous-looking DDL migration that works great in test but grinds the machine to a halt on a production dataset.
- theptip 9y agoThat's a good general point, but Youtube does use MySQL: https://www.mysql.com/customers/view/?id=750 https://www.mysql.com/customers/view/?id=750 http://highscalability.com/youtube-architecture http://highscalability.com/youtube-architecture