[jgraettinger1]

This post doesn't mention the _actual_ answer, which is to:

1) Write a event recording a _desire_ to checkout. 2) Build a view of checkout decisions, which compares requests against inventory levels and produces checkout _results_. This is a stateful stream/stream join. 3) Read out the checkout decision to respond to the user, or send them an email, or whatever.

CDC is great and all, too, but there are architectures where ^ makes more sense than sticking a database in front.

Admittedly working up highly available, stateful stream-stream joins which aren't challenging to operate in production is... hard, but getting better.

[fuckadtech]

Hard is an understatement. Particularly so if you are using Kafka Streams to attempt to run a highly available, fault tolerant, zero downtime, etc., service. The race condition and compaction bugs in that library are not fun to debug.