Hacker News Reader

Ya but say I'm a small business and only have 6 servers for my website

Why do I need to take all 6 offline to do maintenance?

Because you (accidentally or otherwise) built your infrastructure to need to. It's possible to build it so you don't have to, but most don't.

Because likely there is one master, authoritative data source and that has to go down at some point.

If you need to change something in your DB wouldn't you just have a job running in the background doing the migration and have your application code handle both cases when reading the DB (migrated/unmigrated)?

You say "just" like you think that sort of thing is easy. Nothing could be farther from the truth.

For one thing in many DBs certain (often nessesary) schema changes require a global write lock.

It's much much easier to just show down for 15 minutes or less than spend hundreds of hours of engineering effort.

Reply on news.ycombinator.com