I know the CAP theorem, but that's not what is going on here. And now again you are saying that the data loss is a bug. It's not! Like I said, it's by design, they are probably using a fire-and-forget methodology for writing the comments. Do you seriously think there is a bug in PHP or their PHP code that is making a very little percentage of comments get lost? Besides, they have moved away from PHP long time ago for their backend. They are using a combination of Java, Scala, etc. Software that loses some data instead of crashing when under heavy load is not bad software. It has its uses, eg: massive amount (per unit of time) of unimportant messages that no one is willing to pay for.