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Underlying schema or code changes that drastically affect the service's availability. In terms of mysql you are talking locked tables when there is a schema cha
by chuhnk 16y ago
Underlying schema or code changes that drastically affect the service's availability. In terms of mysql you are talking locked tables when there is a schema change. But then I dont know if they still use mysql, they were talking about a move to cassandra. At that scale it is never simple. If a change takes 30 seconds on your dev machine it is not going to be that way in production with a billion rows partitioned across multiple tables.
I am actually curious as to what this "deep" issue is they speak of.
You guys got any examples of infrastructure issues that could cause availability problems in a large scale environment?
- amix 16y agoSchema changes on big tables take hours/days depending on their size. You don't do this in production. What you normally do in a MySQL setup is to run a master-master with one active write master. This way you can run optimizations on one master and switch masters without putting your whole production system in jeopardy. Read more about Flickr's setup for more details. There are tons of things that can go wrong in large scale environments (network issues, load balancing, slow code, databases starting to swap, databases starting to use a lot of IO etc.)
- tlrobinson 16y agoI know they've started deploying a Cassandra cluster alongside their existing MySQL cluster for at least a couple months. I don't know how close they are to switching over completely, but maybe that has something to do with it...