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Koan 3 of 19

Too Many to Hold

The system speaks. But a thousand events pour out every second.
Too many to hold. But if you count them, a pattern appears.
checkout-svc — live event stream 0 events

The system is getting slow. Is it getting worse?

Can you tell from this stream of events?
what you built from the raw events
25 20 15 10 5 events / sec

What just happened when you clicked that button?

What you just built — a number that measures something over time — has a name. What is it called?

Metric

A metric is a measurement captured over time.

It tells you how much, how fast, how often — the vital signs of a system.

You didn't just learn what a metric is. You built one.


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