In this chapter
“There’s never enough time to do it right, but there’s always enough time to do it over.”
—Jack Bergman
Computers are pretty good at performing accurate calculations. However, when computers work together in a distributed system, like many streaming systems, accuracy becomes a little bit more (I mean, a lot more) complicated. Sometimes, we may not want 100% accuracy because other more important requirements need to be met. “Why would we want wrong answers?” you might ask. This is a great question, and it is the one that we need to ask when designing a streaming system. In this chapter, we are going to discuss an important topic related to accuracy in streaming systems: delivery semantics.
In the previous chapter, the team built a credit card fraud detection system which can make a decision within 20 milliseconds for each transaction and store the result in a database. Now, let’s ask an important question when building any distributed system: what if any failure happens?
