For three years, our reporting pipeline at the platform ran on nightly batch jobs. Every night at 2am, a fleet of Go workers would call the Amazon Advertising API to pull the previous day's campaign performance data for 2,000+ advertisers. It worked. Until it did not scale. The problems accumulated over time: API rate limits tightened, some advertisers grew to hundreds of campaigns making their nightly sync take 20 minutes, and any API downtime meant the entire previous day's data was missing. Most importantly, our bidding algorithms were always working with data that was at least 24 hours stale. Amazon Marketing Stream changed all of this. What Is Amazon Marketing Stream? Amazon Marketing Stream (AMS) is Amazon's event-driven reporting system that delivers advertising performance data as near-real-time events via SNS → SQS. Instead of you pulling data from Amazon, Amazon pushes data to you as events — impressions, clicks, spend, conversions — typically 3–5 hours afte...